Note 1: I - Debugging, Integrated on Chip; H - Debugging, available using Debug Header.
2: One pin is input-only.
Data Sheet Index: (Unshaded devices are described in this document.)
1: DS41579PIC16(L)F1782/3 Data Sheet, 28-Pin Flash, 8-bit Advanced Analog MCUs.
2: DS41637PIC16(L)F1784/6/7 Data Sheet, 28/40/44-Pin Flash, 8-bit Advanced Analog MCUs.
3: DS41675PIC16(L)F1788/9 Data Sheet, 28/40/44-Pin Flash, 8-bit Advanced Analog MCUs.
Note:For other small form-factor package availability and marking information, please visit
http://www.microchip.com/packaging or contact your local sales office.
2.0Enhanced Mid-Range CPU ........................................................................................................................................................ 27
12.0 Date EEPROM and Flash Program Memory Control ............................................................................................................... 121
15.0 Fixed Voltage Reference (FVR) ............................................................................................................................................... 167
16.0 Temperature Indicator.............................................................................................................................................................. 171
27.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 301
29.0 In-Circuit Serial Programming™ (ICSP™) ............................................................................................................................... 387
30.0 Instruction Set Summary.......................................................................................................................................................... 389
32.0 DC and AC Characteristics Graphs and Tables....................................................................................................................... 435
33.0 Development Support............................................................................................................................................................... 453
Index .................................................................................................................................................................................................. 481
The Microchip Web Site..................................................................................................................................................................... 489
Customer Change Notification Service .............................................................................................................................................. 489
Customer Support .............................................................................................................................................................................. 489
Product Identification System ............................................................................................................................................................ 491
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Errata
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DS41675A-page 14Preliminary 2013 Microchip Technology Inc.
1.0DEVICE OVERVIEW
The PIC16(L)F1788/9 are described within this data
sheet. They are available in 28-pin packages. Figure 1-1
shows a block diagram of the PIC16(L)F1788/9 devices.
Table 1-2 shows the pinout descriptions.
Reference Table 1-1 for peripherals available per device.
TABLE 1-1:DEVICE PERIPHERAL
SUMMARY
Peripheral
PIC16(L)F1788
PIC16(L)F1789
Analog-to-Digital Converter (ADC)●●
Digital-to-Analog Converter (DAC)●●
Fixed Voltage Reference (FVR)●●
Reference Clock Module●●
Temperature Indicator●●
Capture/Compare/PWM (CCP/ECCP) Modules
DS41675A-page 26Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
Data Bus
8
14
Program
Bus
Instruction reg
Program Counter
8 LevelStack
(13-bit)
Direct Addr
7
12
Addr MUX
FSR reg
STATUS reg
MUX
ALU
Power-up
Timer
Oscillator
Start-up Timer
Power-on
Reset
Watchdog
Timer
Instruction
Decode &
Control
Timing
Generation
OSC1/CLKIN
OSC2/CLKOUT
V
DD
8
8
Brown-out
Reset
12
3
VSS
Internal
Oscillator
Block
Data Bus
8
14
Program
Bus
Instruction reg
Program Counter
8 LevelStack
(13-bit)
Direct Addr
7
Addr MUX
FSR reg
STATUS reg
MUX
ALU
W reg
Instruction
Decode &
Control
Timing
Generation
V
DD
8
8
3
VSS
Internal
Oscillator
Block
15
Data Bus
8
14
Program
Bus
Instruction Reg
Program Counter
16-Level Stack
(15-bit)
Direct Addr
7
RAM Addr
Addr MUX
Indirect
Addr
FSR0 Reg
STATUS Reg
MUX
ALU
Instruction
Decode and
Control
Timing
Generation
VDD
8
8
3
VSS
Internal
Oscillator
Block
RAM
FSR regFSR reg
FSR1 Reg
15
15
MUX
15
Program Memory
Read (PMR)
12
FSR regFSR reg
BSR Reg
5
ConfigurationConfigurationConfiguration
Flash
Program
Memory
2.0ENHANCED MID-RANGE CPU
This family of devices contain an enhanced mid-range
8-bit CPU core. The CPU has 49 instructions. Interrupt
capability includes automatic context saving. The
hardware stack is 16 levels deep and has Overflow and
Underflow Reset capability. Direct, Indirect, and
FIGURE 2-1:CORE BLOCK DIAGRAM
Relative addressing modes are available. Two File
Select Registers (FSRs) provide the ability to read
program and data memory.
During interrupts, certain registers are automatically
saved in shadow registers and restored when returning
from the interrupt. This saves stack space and user
code. See 8.5 “Automatic Context Saving” for more
information.
2.216-level Stack with Overflow and
Underflow
These devices have an external stack memory 15 bits
wide and 16 words deep. A Stack Overflow or Underflow will set the appropriate bit (STKOVF or STKUNF)
in the PCON register, and if enabled will cause a software Reset. See Section 3.5 “Stack” for more details.
2.3File Select Registers
There are two 16-bit File Select Registers (FSR). FSRs
can access all file registers and program memory,
which allows one Data Pointer for all memory. When an
FSR points to program memory, there is one additional
instruction cycle in instructions using INDF to allow the
data to be fetched. General purpose memory can now
also be addressed linearly, providing the ability to
access contiguous data larger than 80 bytes. There are
also new instructions to support the FSRs. See
Section 3.6 “Indirect Addressing” for more details.
2.4Instruction Set
There are 49 instructions for the enhanced mid-range
CPU to support the features of the CPU. See
Section 30.0 “Instruction Set Summary” for more
details.
DS41675A-page 28Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
3.0MEMORY ORGANIZATION
These devices contain the following types of memory:
• Program Memory
- Configuration Words
- Device ID
-User ID
- Flash Program Memory
• Data Memory
- Core Registers
- Special Function Registers
- General Purpose RAM
- Common RAM
• Data EEPROM memory
Note 1: The Data EEPROM Memory and the
method to access Flash memory through
the EECON registers is described in
Section 12.0 “Data EEPROM and Flash
Program Memory Control”.
(1)
The following features are associated with access and
control of program memory and data memory:
• PCL and PCLATH
•Stack
• Indirect Addressing
3.1Program Memory Organization
The enhanced mid-range core has a 15-bit program
counter capable of addressing a 32K x 14 program
memory space. Table 3-1 shows the memory sizes
implemented for the PIC16(L)F1788/9 family. Accessing
a location above these boundaries will cause a
wrap-around within the implemented memory space.
The Reset vector is at 0000h and the interrupt vector is
at 0004h (see Figure 3-1).
TABLE 3-1:DEVICE SIZES AND ADDRESSES
DeviceProgram Memory Space (Words)Last Program Memory Address
;select data
RETLW DATA0;Index0 data
RETLW DATA1;Index1 data
RETLW DATA2
RETLW DATA3
my_function
;… LOTS OF CODE…
MOVLWDATA_INDEX
call constants
;… THE CONSTANT IS IN W
FIGURE 3-1:PROGRAM MEMORY MAP
AND STACK FOR
PIC16(L)F1788/9
3.1.1READING PROGRAM MEMORY AS
DATA
There are two methods of accessing constants in
program memory. The first method is to use tables of
RETLW instructions. The second method is to set an
FSR to point to the program memory.
3.1.1.1RETLW Instruction
The RETLW instruction can be used to provide access
to tables of constants. The recommended way to create
such a table is shown in Example 3-1.
EXAMPLE 3-1:RETLW INSTRUCTION
The BRW instruction makes this type of table very
simple to implement. If your code must remain portable
with previous generations of microcontrollers, then the
BRW instruction is not available so the older table read
method must be used.
3.1.1.2Indirect Read with FSR
The program memory can be accessed as data by
setting bit 7 of the FSRxH register and reading the
matching INDFx register. The MOVIW instruction will
place the lower 8 bits of the addressed word in the W
register. Writes to the program memory cannot be performed via the INDF registers. Instructions that access
the program memory via the FSR require one extra
instruction cycle to complete. Example 3-2
demonstrates accessing the program memory via an
FSR.
The high directive will set bit<7> if a label points to a
location in program memory.
DS41675A-page 30Preliminary 2013 Microchip Technology Inc.
EXAMPLE 3-2:ACCESSING PROGRAM
constants
RETLW DATA0;Index0 data
RETLW DATA1;Index1 data
RETLW DATA2
RETLW DATA3
x00h or x80hINDF0
x01h or x81hINDF1
x02h or x82hPCL
x03h or x83hSTATUS
x04h or x84hFSR0L
x05h or x85hFSR0H
x06h or x86hFSR1L
x07h or x87hFSR1H
x08h or x88hBSR
x09h or x89hWREG
x0Ah or x8AhPCLATH
x0Bh or x8BhINTCON
3.2Data Memory Organization
The data memory is partitioned in 32 memory banks
with 128 bytes in a bank. Each bank consists of
(Figure 3-2):
• 12 core registers
• 20 Special Function Registers (SFR)
• Up to 80 bytes of General Purpose RAM (GPR)
• 16 bytes of common RAM
The active bank is selected by writing the bank number
into the Bank Select Register (BSR). Unimplemented
memory will read as ‘0’. All data memory can be
accessed either directly (via instructions that use the
file registers) or indirectly via the two File Select
Registers (FSR). See Section 3.6 “Indirect
Addressing” for more information.
Data memory uses a 12-bit address. The upper 7-bits
of the address define the Bank address and the lower
5-bits select the registers/RAM in that bank.
3.2.1CORE REGISTERS
The core registers contain the registers that directly
affect the basic operation. The core registers occupy
the first 12 addresses of every data memory bank
(addresses x00h/x08h through x0Bh/x8Bh). These
registers are listed below in Ta b l e 3 - 2. For detailed
information, see Tab le 3 -11 .
TABLE 3-2:CORE REGISTERS
DS41675A-page 32Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
3.2.1.1STATUS Register
The STATUS register, shown in Register 3-1, contains:
• the arithmetic status of the ALU
• the Reset status
The STATUS register can be the destination for any
instruction, like any other register. If the STATUS
register is the destination for an instruction that affects
the Z, DC or C bits, then the write to these 3 bits is
disabled. These bits are set or cleared according to the
device logic. Furthermore, the TO
writable. Therefore, the result of an instruction with the
STATUS register as destination may be different than
intended.
and PD bits are not
For example, CLRF STATUS will clear the upper 3 bits
and set the Z bit. This leaves the STATUS register as
‘000u u1uu’ (where u = unchanged).
It is recommended, therefore, that only BCF, BSF,SWAPF and MOVWF instructions are used to alter the
STATUS register, because these instructions do not
affect any Status bits. For other instructions not
affecting any Status bits (Refer to Section 30.0
“Instruction Set Summary”).
Note:The C and DC bits operate as Borrow and
Digit Borrow
subtraction.
out bits, respectively, in
3.3Register Definitions: Status
REGISTER 3-1:STATUS: STATUS REGISTER
U-0U-0U-0R-1/qR-1/qR/W-0/uR/W-0/uR/W-0/u
———TOPDZDC
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is clearedq = Value depends on condition
(1)
(1)
C
bit 7-5Unimplemented: Read as ‘0’
bit 4TO
bit 3PD
bit 2Z: Zero bit
bit 1DC: Digit Carry/Digit Borrow
bit 0C: Carry/Borrow
Note 1: For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the
second operand.
: Time-Out bit
1 = After power-up, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occurred
: Power-Down bit
1 = After power-up or by the CLRWDT instruction
0 = By execution of the SLEEP instruction
1 = The result of an arithmetic or logic operation is zero
0 = The result of an arithmetic or logic operation is not zero
bit (ADDWF, ADDLW, SUBLW, SUBWF instructions)
1 = A carry-out from the 4th low-order bit of the result occurred
0 = No carry-out from the 4th low-order bit of the result
(1)
bit
(ADDWF, ADDLW, SUBLW, SUBWF instructions)
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
The Special Function Registers are registers used by
the application to control the desired operation of
peripheral functions in the device. The Special Function
Registers occupy the 20 bytes after the core registers of
every data memory bank (addresses x0Ch/x8Ch
through x1Fh/x9Fh). The registers associated with the
operation of the peripherals are described in the
appropriate peripheral chapter of this data sheet.
3.3.2GENERAL PURPOSE RAM
There are up to 80 bytes of GPR in each data memory
bank. The Special Function Registers occupy the 20
bytes after the core registers of every data memory
bank (addresses x0Ch/x8Ch through x1Fh/x9Fh).
3.3.2.1Linear Access to GPR
The general purpose RAM can be accessed in a
non-banked method via the FSRs. This can simplify
access to large memory structures. See Section 3.6.2
“Linear Data Memory” for more information.
3.3.3COMMON RAM
There are 16 bytes of common RAM accessible from all
banks.
FIGURE 3-2:BANKED MEMORY
PARTITIONING
DS41675A-page 34Preliminary 2013 Microchip Technology Inc.
3.3.4DEVICE MEMORY MAPS
The memory maps for the device family are as shown
in Tables 3-3 through 3-10.
The Program Counter (PC) is 15 bits wide. The low byte
comes from the PCL register, which is a readable and
writable register. The high byte (PC<14:8>) is not directly
readable or writable and comes from PCLATH. On any
Reset, the PC is cleared. Figure 3-3 shows the five
situations for the loading of the PC.
FIGURE 3-3:LOADING OF PC IN
DIFFERENT SITUATIONS
3.4.3COMPUTED FUNCTION CALLS
A computed function CALL allows programs to maintain
tables of functions and provide another way to execute
state machines or look-up tables. When performing a
table read using a computed function CALL, care
should be exercised if the table location crosses a PCL
memory boundary (each 256-byte block).
If using the CALL instruction, the PCH<2:0> and PCL
registers are loaded with the operand of the CALL
instruction. PCH<6:3> is loaded with PCLATH<6:3>.
The CALLW instruction enables computed calls by combining PCLATH and W to form the destination address.
A computed CALLW is accomplished by loading the W
register with the desired address and executing CALLW.
The PCL register is loaded with the value of W and
PCH is loaded with PCLATH.
3.4.4BRANCHING
The branching instructions add an offset to the PC.
This allows relocatable code and code that crosses
page boundaries. There are two forms of branching,
BRW and BRA. The PC will have incremented to fetch
the next instruction in both cases. When using either
branching instruction, a PCL memory boundary may be
crossed.
If using BRW, load the W register with the desired
unsigned address and execute BRW. The entire PC will
be loaded with the address PC + 1 + W.
If using BRA, the entire PC will be loaded with PC + 1 +,
the signed value of the operand of the BRA instruction.
3.4.1MODIFYING PCL
Executing any instruction with the PCL register as the
destination simultaneously causes the Program
Counter PC<14:8> bits (PCH) to be replaced by the
contents of the PCLATH register. This allows the entire
contents of the program counter to be changed by
writing the desired upper 7 bits to the PCLATH register.
When the lower 8 bits are written to the PCL register, all
15 bits of the program counter will change to the values
contained in the PCLATH register and those being
written to the PCL register.
3.4.2COMPUTED GOTO
A computed GOTO is accomplished by adding an offset to
the program counter (ADDWF PCL). When performing a
table read using a computed GOTO method, care should
be exercised if the table location crosses a PCL memory
boundary (each 256-byte block). Refer to Application
Note AN556, “Implementing a Table Read” (DS00556).
DS41675A-page 52Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
0x0F
0x0E
0x0D
0x0C
0x0B
0x0A
0x09
0x08
0x07
0x06
0x05
0x04
0x03
0x02
0x01
0x00
0x0000
STKPTR = 0x1F
Initial Stack Configuration:
After Reset, the stack is empty. The
empty stack is initialized so the Stack
Pointer is pointing at 0x1F. If the Stack
Overflow/Underflow Reset is enabled, the
TOSH/TOSL registers will return ‘0’. If
the Stack Overflow/Underflow Reset is
disabled, the TOSH/TOSL registers will
return the contents of stack address 0x0F.
0x1FSTKPTR = 0x1F
Stack Reset Disabled
(STVREN = 0)
Stack Reset Enabled
(STVREN = 1)
TOSH:TOSL
TOSH:TOSL
3.5Stack
All devices have a 16-level x 15-bit wide hardware
stack (refer to Figure 3-1). The stack space is not part
of either program or data space. The PC is PUSHed
onto the stack when CALL or CALLW instructions are
executed or an interrupt causes a branch. The stack is
POPed in the event of a RETURN, RETLW or a RETFIE
instruction execution. PCLATH is not affected by a
PUSH or POP operation.
The stack operates as a circular buffer if the STVREN
bit is programmed to ‘0‘ (Configuration Words). This
means that after the stack has been PUSHed sixteen
times, the seventeenth PUSH overwrites the value that
was stored from the first PUSH. The eighteenth PUSH
overwrites the second PUSH (and so on). The
STKOVF and STKUNF flag bits will be set on an Overflow/Underflow, regardless of whether the Reset is
enabled.
Note:There are no instructions/mnemonics
called PUSH or POP. These are actions
that occur from the execution of the CALL,CALLW, RETURN, RETLW and RETFIE
instructions or the vectoring to an interrupt
address.
3.5.1ACCESSING THE STACK
The stack is available through the TOSH, TOSL and
STKPTR registers. STKPTR is the current value of the
Stack Pointer. TOSH:TOSL register pair points to the
TOP of the stack. Both registers are read/writable. TOS
is split into TOSH and TOSL due to the 15-bit size of
the PC. To access the stack, adjust the value of
STKPTR, which will position TOSH:TOSL, then
read/write to TOSH:TOSL. STKPTR is 5 bits to allow
detection of overflow and underflow.
Note:Care should be taken when modifying the
STKPTR while interrupts are enabled.
During normal program operation, CALL, CALLW and
Interrupts will increment STKPTR while RETLW,RETURN, and RETFIE will decrement STKPTR. At any
time, STKPTR can be inspected to see how much
stack is left. The STKPTR always points at the currently
used place on the stack. Therefore, a CALL or CALLW
will increment the STKPTR and then write the PC, and
a return will unload the PC and then decrement the
STKPTR.
Reference Figure 3-4 through Figure 3-7 for examples
of accessing the stack.
This figure shows the stack configuration
after the first CALL or a single interrupt.
If a RETURN instruction is executed, the
return address will be placed in the
Program Counter and the Stack Pointer
decremented to the empty state (0x1F).
TOSH:TOSL
0x0F
0x0E
0x0D
0x0C
0x0B
0x0A
0x09
0x08
0x07
Return Address0x06
Return Address0x05
Return Address0x04
Return Address0x03
Return Address0x02
Return Address0x01
Return Address0x00
STKPTR = 0x06
After seven CALLs or six CALLs and an
interrupt, the stack looks like the figure
on the left. A series of RETURN instructions
will repeatedly place the return addresses
into the Program Counter and pop the stack.
TOSH:TOSL
FIGURE 3-5:ACCESSING THE STACK EXAMPLE 2
FIGURE 3-6:ACCESSING THE STACK EXAMPLE 3
DS41675A-page 54Preliminary 2013 Microchip Technology Inc.
FIGURE 3-7:ACCESSING THE STACK EXAMPLE 4
0x0F
0x0E
0x0D
0x0C
0x0B
0x0A
0x09
0x08
0x07
0x06
0x05
0x04
0x03
0x02
0x01
Return Address0x00
STKPTR = 0x10
When the stack is full, the next CALL or
an interrupt will set the Stack Pointer to
0x10. This is identical to address 0x00
so the stack will wrap and overwrite the
return address at 0x00. If the Stack
Overflow/Underflow Reset is enabled, a
Reset will occur and location 0x00 will
not be overwritten.
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
Return Address
TOSH:TOSL
PIC16(L)F1788/9
3.5.2OVERFLOW/UNDERFLOW RESET
If the STVREN bit in Configuration Words is
programmed to ‘1’, the device will be reset if the stack
is PUSHed beyond the sixteenth level or POPed
beyond the first level, setting the appropriate bits
(STKOVF or STKUNF, respectively) in the PCON
register.
3.6Indirect Addressing
The INDFn registers are not physical registers. Any
instruction that accesses an INDFn register actually
accesses the register at the address specified by the
File Select Registers (FSR). If the FSRn address
specifies one of the two INDFn registers, the read will
return ‘0’ and the write will not occur (though Status bits
may be affected). The FSRn register value is created
by the pair FSRnH and FSRnL.
The FSR registers form a 16-bit address that allows an
addressing space with 65536 locations. These locations
are divided into three memory regions:
Note:Not all memory regions are completely implemented. Consult device memory tables for memory limits.
0x1FFF
FIGURE 3-8:INDIRECT ADDRESSING
DS41675A-page 56Preliminary 2013 Microchip Technology Inc.
3.6.1TRADITIONAL DATA MEMORY
Indirect AddressingDirect Addressing
Bank Select
Location Select
4BSR6
0
From Opcode
FSRxL70
Bank Select
Location Select
00000 00001 0001011111
0x00
0x7F
Bank 0 Bank 1 Bank 2Bank 31
0
FSRxH70
0000
The traditional data memory is a region from FSR
address 0x000 to FSR address 0xFFF. The addresses
correspond to the absolute addresses of all SFR, GPR
and common registers.
The linear data memory is the region from FSR
address 0x2000 to FSR address 0x29AF. This region is
a virtual region that points back to the 80-byte blocks of
GPR memory in all the banks.
Unimplemented memory reads as 0x00. Use of the
linear data memory region allows buffers to be larger
than 80 bytes because incrementing the FSR beyond
one bank will go directly to the GPR memory of the next
bank.
The 16 bytes of common memory are not included in
the linear data memory region.
FIGURE 3-10:LINEAR DATA MEMORY
MAP
3.6.3PROGRAM FLASH MEMORY
To make constant data access easier, the entire
program Flash memory is mapped to the upper half of
the FSR address space. When the MSB of FSRnH is
set, the lower 15 bits are the address in program
memory which will be accessed through INDF. Only the
lower 8 bits of each memory location is accessible via
INDF. Writing to the program Flash memory cannot be
accomplished via the FSR/INDF interface. All
instructions that access program Flash memory via the
FSR/INDF interface will require one additional
instruction cycle to complete.
FIGURE 3-11:PROGRAM FLASH
MEMORY MAP
DS41675A-page 58Preliminary 2013 Microchip Technology Inc.
4.0DEVICE CONFIGURATION
Device configuration consists of Configuration Words,
Code Protection and Device ID.
4.1Configuration Words
There are several Configuration Word bits that allow
different oscillator and memory protection options.
These are implemented as Configuration Word 1 at
8007h and Configuration Word 2 at 8008h.
Note:The DEBUG bit in Configuration Words is
managed automatically by device
development tools including debuggers
and programmers. For normal device
operation, this bit should be maintained as
a ‘1’.
R = Readable bitP = Programmable bitU = Unimplemented bit, read as ‘1’
‘0’ = Bit is cleared‘1’ = Bit is set-n = Value when blank or after Bulk Erase
bit 13 FCMEN: Fail-Safe Clock Monitor Enable bit
bit 12IESO: Internal External Switchover bit
bit 11CLKOUTEN
bit 10-9BOREN<1:0>: Brown-out Reset Enable bits
bit 8CPD
bit 7CP
bit 6MCLRE: MCLR
bit 5PWRTE
bit 4-3WDTE<1:0>: Watchdog Timer Enable bit
MCLREPWRTEWDTE<1:0>FOSC<2:0>
1 = Fail-Safe Clock Monitor and internal/external switchover are both enabled.
0 = Fail-Safe Clock Monitor is disabled
1 = Internal/External Switchover mode is enabled
0 = Internal/External Switchover mode is disabled
: Clock Out Enable bit
FOSC configuration bits are set to LP, XT, HS modes:
If
This bit is ignored, CLKOUT function is disabled. Oscillator function on the CLKOUT pin.
All other FOSC modes:
1 = CLKOUT function is disabled. I/O function on the CLKOUT pin.
0 = CLKOUT function is enabled on the CLKOUT pin
11 = BOR enabled
10 = BOR enabled during operation and disabled in Sleep
01 = BOR controlled by SBOREN bit of the BORCON register
00 = BOR disabled
: Data Code Protection bit
1 = Data memory code protection is disabled
0 = Data memory code protection is enabled
: Code Protection bit
1 = Program memory code protection is disabled
0 = Program memory code protection is enabled
/VPP Pin Function Select bit
If LVP bit =
This bit is ignored.
If LVP bit = 0:
1 =MCLR
0 =MCLR
1 = PWRT disabled
0 = PWRT enabled
11 = WDT enabled
10 = WDT enabled while running and disabled in Sleep
01 = WDT controlled by the SWDTEN bit in the WDTCON register
00 = WDT disabled
1:
/VPP pin function is MCLR; Weak pull-up enabled.
/VPP pin function is digital input; MCLR internally disabled; Weak pull-up under control of
WPUE3 bit.
: Power-up Timer Enable bit
(1)
DS41675A-page 60Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
REGISTER 4-1:CONFIG1: CONFIGURATION WORD 1 (CONTINUED)
bit 2-0FOSC<2:0>: Oscillator Selection bits
111 = ECH: External Clock, High-Power mode (4-20 MHz): device clock supplied to CLKIN pin
110 = ECM: External Clock, Medium-Power mode (0.5-4 MHz): device clock supplied to CLKIN pin
101 = ECL: External Clock, Low-Power mode (0-0.5 MHz): device clock supplied to CLKIN pin
100 = INTOSC oscillator: I/O function on CLKIN pin
011 = EXTRC oscillator: External RC circuit connected to CLKIN pin
010 = HS oscillator: High-speed crystal/resonator connected between OSC1 and OSC2 pins
001 = XT oscillator: Crystal/resonator connected between OSC1 and OSC2 pins
000 =LP oscillator: Low-power crystal connected between OSC1 and OSC2 pins
Note 1: The entire data EEPROM will be erased when the code protection is turned off during an erase. Once the
Data Code Protection bit is enabled, (CPD
ICSP) can disable the Data Code Protection (CPD
is executed, the entire program Flash memory, data EEPROM and configuration memory will be erased.
= 0), the Bulk Erase Program Memory Command (through
R = Readable bitP = Programmable bitU = Unimplemented bit, read as ‘1’
‘0’ = Bit is cleared‘1’ = Bit is set-n = Value when blank or after Bulk Erase
VCAPEN
———WRT<1:0>
LPBORBORVSTVRENPLLEN
bit 13LVP: Low-Voltage Programming Enable bit
bit 12
bit 11
bit 10BORV: Brown-out Reset Voltage Selection bit
bit 9STVREN: Stack Overflow/Underflow Reset Enable bit
bit 8PLLEN: PLL Enable bit
bit 7-6Unimplemented: Read as ‘1’
bit 5VCAPEN
bit 4-2Unimplemented: Read as ‘1’
bit 1-0WRT<1:0>: Flash Memory Self-Write Protection bits
1 = Low-voltage programming enabled
0 = High-voltage on MCLR
: In-Circuit Debugger Mode bit
DEBUG
1 = In-Circuit Debugger disabled, ICSPCLK and ICSPDAT are general purpose I/O pins
0 = In-Circuit Debugger enabled, ICSPCLK and ICSPDAT are dedicated to the debugger
: Low-Power BOR Enable bit
LPBOR
1 = Low-Power Brown-out Reset is disabled
0 = Low-Power Brown-out Reset is enabled
1 = Brown-out Reset voltage (Vbor), low trip point selected.
0 = Brown-out Reset voltage (Vbor), high trip point selected.
1 = Stack Overflow or Underflow will cause a Reset
0 = Stack Overflow or Underflow will not cause a Reset
1 = 4xPLL enabled
0 = 4xPLL disabled
1 = VCAP functionality is disabled on RA6
0 = V
8
: Voltage Regulator Capacitor Enable bit
CAP functionality is enabled on RA6
kW Flash memory:
11 = Write protection off
10 = 000h to 1FFh write-protected, 200h to 3FFFh may be modified by EECON control
01 = 000h to 1FFFh write-protected, 2000h to 3FFFh may be modified by EECON control
00 = 000h to 3FFFh write-protected, no addresses may be modified by EECON control
must be used for programming
(1)
(3)
(4)
(2)
Note 1:The LVP bit cannot be programmed to ‘0’ when Programming mode is entered via LVP.
2:Not implemented on PIC16LF1788/9.
3:The DEBUG
and programmers. For normal device operation, this bit should be maintained as a '1'.
4:See Vbor parameter for specific trip point voltages.
DS41675A-page 62Preliminary 2013 Microchip Technology Inc.
bit in Configuration Words is managed automatically by device development tools including debuggers
4.3Code Protection
Code protection allows the device to be protected from
unauthorized access. Program memory protection and
data EEPROM protection are controlled independently.
Internal access to the program memory and data
EEPROM are unaffected by any code protection
setting.
4.3.1PROGRAM MEMORY PROTECTION
The entire program memory space is protected from
external reads and writes by the CP
Words. When CP
program memory are inhibited and a read will return all
‘0’s. The CPU can continue to read program memory,
regardless of the protection bit settings. Writing the
program memory is dependent upon the write
protection setting. See Section 4.4 “Write
Protection” for more information.
= 0, external reads and writes of
4.3.2DATA EEPROM PROTECTION
The entire data EEPROM is protected from external
reads and writes by the CPD
external reads and writes of data EEPROM are
inhibited. The CPU can continue to read and write data
EEPROM regardless of the protection bit settings.
bit in Configuration
bit. When CPD = 0,
PIC16(L)F1788/9
4.4Write Protection
Write protection allows the device to be protected from
unintended self-writes. Applications, such as
bootloader software, can be protected while allowing
other regions of the program memory to be modified.
The WRT<1:0> bits in Configuration Words define the
size of the program memory block that is protected.
4.5User ID
Four memory locations (8000h-8003h) are designated
as ID locations where the user can store checksum or
other code identification numbers. These locations are
readable and writable during normal execution. See
Section 12.5 “User ID, Device ID and Configuration
Word Access”for more information on accessing
these memory locations.
checksum calculation, see the “PIC16(L)F178XMemory Programming Specification” (DS41457).
The memory location 8006h is where the Device ID and
Revision ID are stored. The upper nine bits hold the
Device ID. The lower five bits hold the Revision ID. See
Section 12.5 “User ID, Device ID and Configuration
Word Access” for more information on accessing
these memory locations.
Development tools, such as device programmers and
debuggers, may be used to read the Device ID and
Revision ID.
4.7Register Definitions: Device ID
REGISTER 4-3:DEVID: DEVICE ID REGISTER
RRRRRR
DEV<13:8>
bit 13bit 8
RRRRRRRR
DEV<7:0>
bit 7bit 0
Legend:
R = Readable bit
‘1’ = Bit is set‘0’ = Bit is cleared
bit 13-0DEV<13:0>: Device ID bits
REGISTER 4-4:REVID: REVISION ID REGISTER
RRRRRR
REV<13:8>
bit 13bit 8
RRRRRRRR
REV<7:0>
bit 7bit 0
Legend:
R = Readable bit
‘1’ = Bit is set‘0’ = Bit is cleared
bit 13-0REV<13:0>: Revision ID bits
DS41675A-page 64Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
Note 1:See Table 5-1 for BOR active conditions.
Device
Reset
Power-on
Reset
WDT
Time-out
Brown-out
Reset
LPBOR
Reset
RESET Instruction
MCLRE
Sleep
BOR
Active
(1)
PWRT
R
Done
PWRTE
LFINTOSC
VDD
Exit
Stack
Pointer
5.0RESETS
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 5-1.
There are multiple ways to reset this device:
• Power-On Reset (POR)
• Brown-Out Reset (BOR)
• Low-Power Brown-Out Reset (LPBOR)
•MCLR Reset
•WDT Reset
• RESET instruction
• Stack Overflow
• Stack Underflow
• Programming mode exit
To a ll o w VDD to stabilize, an optional power-up timer
can be enabled to extend the Reset time after a BOR
or POR event.
FIGURE 5-1:SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
The POR circuit holds the device in Reset until VDD has
reached an acceptable level for minimum operation.
Slow rising V
performance may require greater than minimum V
The PWRT, BOR or MCLR
extend the start-up period until all device operation
conditions have been met.
5.1.1POWER-UP TIMER (PWRT)
The Power-up Timer provides a nominal 64 ms
time-out on POR or Brown-out Reset.
The device is held in Reset as long as PWRT is active.
The PWRT delay allows additional time for the V
rise to an acceptable level. The Power-up Timer is
enabled by clearing the PWRTE bit in Configuration
Words.
The Power-up Timer starts after the release of the POR
and BOR.
For additional information, refer to Application Note
AN607, “Power-up Trouble Shooting” (DS00607).
TABLE 5-1:BOR OPERATING MODES
BOREN<1:0>SBORENDevice ModeBOR Mode
DD, fast operating speeds or analog
DD.
features can be used to
DD to
11XXActiveWaits for BOR ready
5.2Brown-Out Reset (BOR)
The BOR circuit holds the device in Reset when VDD
reaches a selectable minimum level. Between the
POR and BOR, complete voltage range coverage for
execution protection can be implemented.
The Brown-out Reset module has four operating
modes controlled by the BOREN<1:0> bits in Configuration Words. The four operating modes are:
• BOR is always on
• BOR is off when in Sleep
• BOR is controlled by software
• BOR is always off
Refer to Tab le 5 -1 for more information.
The Brown-out Reset voltage level is selectable by
configuring the BORV bit in Configuration Words.
DD noise rejection filter prevents the BOR from
A V
triggering on small events. If V
a duration greater than parameter T
will reset. See Figure 5-2 for more information.
Instruction Execution upon:
Release of POR or Wake-up from Sleep
DD falls below VBOR for
BORDC, the device
(1)
(BORRDY = 1)
10X
01
00XXDisabled
Note 1: In these specific cases, “Release of POR” and “Wake-up from Sleep”, there is no delay in start-up. The BOR
ready flag, (BORRDY = 1), will be set before the CPU is ready to execute instructions because the BOR
circuit is forced on by the BOREN<1:0> bits.
1XActiveWaits for BOR ready
0XDisabled
5.2.1BOR IS ALWAYS ON
When the BOREN bits of Configuration Words are
programmed to ‘11’, the BOR is always on. The device
start-up will be delayed until the BOR is ready and V
is higher than the BOR threshold.
BOR protection is active during Sleep. The BOR does
not delay wake-up from Sleep.
5.2.2BOR IS OFF IN SLEEP
When the BOREN bits of Configuration Words are
programmed to ‘10’, the BOR is on, except in Sleep.
The device start-up will be delayed until the BOR is
ready and V
BOR protection is not active during Sleep. The device
wake-up will be delayed until the BOR is ready.
DD is higher than the BOR threshold.
AwakeActive
SleepDisabled
5.2.3BOR CONTROLLED BY SOFTWARE
When the BOREN bits of Configuration Words are
programmed to ‘01’, the BOR is controlled by the
DD
SBOREN bit of the BORCON register. The device
start-up is not delayed by the BOR ready condition or
the V
BOR protection begins as soon as the BOR circuit is
ready. The status of the BOR circuit is reflected in the
BORRDY bit of the BORCON register.
BOR protection is unchanged by Sleep.
Waits for BOR ready (BORRDY = 1)
(1)
(BORRDY = 1)
Begins immediately (BORRDY = x)
DD level.
DS41675A-page 66Preliminary 2013 Microchip Technology Inc.
FIGURE 5-2: BROWN-OUT SITUATIONS
TPWRT
(1)
VBOR
V
DD
Internal
Reset
VBOR
V
DD
Internal
Reset
TPWRT
(1)
< TPWRT
TPWRT
(1)
VBOR
V
DD
Internal
Reset
Note 1: TPWRT delay only if PWRTE bit is programmed to ‘0’.
PIC16(L)F1788/9
5.3Register Definitions: BOR Control
REGISTER 5-1:BORCON: BROWN-OUT RESET CONTROL REGISTER
R/W-1/uR/W-0/uU-0U-0U-0U-0U-0R-q/u
SBORENBORFS
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is clearedq = Value depends on condition
bit 7SBOREN: Software Brown-out Reset Enable bit
If BOREN <1:0> in Configuration Words
SBOREN is read/write, but has no effect on the BOR.
If BOREN <1:0> in Configuration Words =
1 = BOR Enabled
0 = BOR Disabled
bit 6BORFS: Brown-out Reset Fast Start bit
If BOREN<1:0> = 11 (Always on) or BOREN<1:0> = 00 (Always off)
BORFS is Read/Write, but has no effect.
If BOREN <1:0> =
1 = Band gap is forced on always (covers sleep/wake-up/operating cases)
0 = Band gap operates normally, and may turn off
bit 5-1Unimplemented: Read as ‘0’
bit 0BORRDY: Brown-out Reset Circuit Ready Status bit
1 = The Brown-out Reset circuit is active
0 = The Brown-out Reset circuit is inactive
—————BORRDY
01:
01:
(1)
10 (Disabled in Sleep) or BOREN<1:0> = 01 (Under software control):
Note 1: BOREN<1:0> bits are located in Configuration Words.
The Low-Power Brown-Out Reset (LPBOR) is an
essential part of the Reset subsystem. Refer to
Figure 5-1 to see how the BOR interacts with other
modules.
The LPBOR is used to monitor the external V
When too low of a voltage is detected, the device is
held in Reset. When this occurs, a register bit (BOR) is
changed to indicate that a BOR Reset has occurred.
The same bit is set for both the BOR and the LPBOR.
Refer to Register 5-2.
DD pin.
5.4.1ENABLING LPBOR
The LPBOR is controlled by the LPBOR bit of
Configuration Words. When the device is erased, the
LPBOR module defaults to disabled.
5.4.1.1LPBOR Module Output
The output of the LPBOR module is a signal indicating
whether or not a Reset is to be asserted. This signal is
OR’d together with the Reset signal of the BOR
module to provide the generic BOR
to the PCON register and to the power control block.
signal, which goes
5.5MCLR
The MCLR is an optional external input that can reset
the device. The MCLR
MCLRE bit of Configuration Words and the LVP bit of
Configuration Words (Table 5-2).
TABLE 5-2:MCLR CONFIGURATION
MCLRELVPMCLR
00Disabled
10Enabled
x1Enabled
5.5.1MCLR ENABLED
When MCLR is enabled and the pin is held low, the
device is held in Reset. The MCLR
V
DD through an internal weak pull-up.
The device has a noise filter in the MCLR
The filter will detect and ignore small pulses.
Note:A Reset does not drive the MCLR
5.5.2MCLR DISABLED
When MCLR is disabled, the pin functions as a general
purpose input and the internal weak pull-up is under
software control. See Section 13.9 “PORTD Regis-
ters (PIC16(L)F1789 only)” for more information.
function is controlled by the
pin is connected to
Reset path.
pin low.
5.6Watchdog Timer (WDT) Reset
The Watchdog Timer generates a Reset if the firmware
does not issue a CLRWDT instruction within the time-out
period. The TO
changed to indicate the WDT Reset. See Section 11.0
“Watchdog Timer (WDT)” for more information.
and PD bits in the STATUS register are
5.7RESET Instruction
A RESET instruction will cause a device Reset. The RI
bit in the PCON register will be set to ‘0’. See Ta b le 5 - 4
for default conditions after a RESET instruction has
occurred.
5.8Stack Overflow/Underflow Reset
The device can reset when the Stack Overflows or
Underflows. The STKOVF or STKUNF bits of the PCON
register indicate the Reset condition. These Resets are
enabled by setting the STVREN bit in Configuration
Words. See Section 5.8 “Stack Overflow/Underflow
Reset” for more information.
5.9Programming Mode Exit
Upon exit of Programming mode, the device will
behave as if a POR had just occurred.
5.10Power-Up Timer
The Power-up Timer optionally delays device execution
after a BOR or POR event. This timer is typically used to
allow VDD to stabilize before allowing the device to start
running.
The Power-up Timer is controlled by the PWRTE
Configuration Words.
bit of
5.11Start-up Sequence
Upon the release of a POR or BOR, the following must
occur before the device will begin executing:
1. Power-up Timer runs to completion (if enabled).
2. Oscillator start-up timer runs to completion (if
required for oscillator source).
3. MCLR
The total time-out will vary based on oscillator configuration and Power-up Timer configuration. See
Section 6.0 “Oscillator Module (with Fail-Safe
Clock Monitor)” for more information.
The Power-up Timer and oscillator start-up timer run
independently of MCLR
long enough, the Power-up Timer and oscillator
start-up timer will expire. Upon bringing MCLR
device will begin execution immediately (see
Figure 5-3). This is useful for testing purposes or to
synchronize more than one device operating in parallel.
must be released (if enabled).
Reset. If MCLR is kept low
high, the
DS41675A-page 68Preliminary 2013 Microchip Technology Inc.
Upon any Reset, multiple bits in the STATUS and
PCON register are updated to indicate the cause of the
Reset. Ta b le 5 - 3 and Ta bl e 5 -4 show the Reset
conditions of these registers.
TABLE 5-3:RESET STATUS BITS AND THEIR SIGNIFICANCE
STKOVF STKUNF RWDT RMCLRRIPORBORTOPDCondition
00 1 1 10 x11Power-on Reset
00 1 1 10 x0xIllegal, TO
00 1 1 10 xx0Illegal, PD is set on POR
00 u 1 1u 011Brown-out Reset
uu 0 u uu u0uWDT Reset
uu u u uu u00WDT Wake-up from Sleep
uu u u uu u10Interrupt Wake-up from Sleep
uu u 0 uu uuuMCLR
uu u 0 uu u10MCLR
uuuu0uuuuRESET Instruction Executed
1u u u uu uuuStack Overflow Reset (STVREN = 1)
u1 u u uu uuuStack Underflow Reset (STVREN = 1)
is set on POR
Reset during normal operation
Reset during Sleep
TABLE 5-4:RESET CONDITION FOR SPECIAL REGISTERS
Condition
Power-on Reset0000h---1 100000-- 110x
MCLR
Reset during normal operation0000h---u uuuuuu-- 0uuu
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’.
Note 1: When the wake-up is due to an interrupt and Global Enable bit (GIE) is set, the return address is pushed on
the stack and PC is loaded with the interrupt vector (0004h) after execution of PC + 1.
Program
Counter
(1)
STATUS
Register
---1 0uuuuu-- uuuu
PCON
Register
DS41675A-page 70Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
5.13Power Control (PCON) Register
The Power Control (PCON) register contains flag bits
to differentiate between a:
HC = Bit is cleared by hardwareHS = Bit is set by hardware
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-m/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is clearedq = Value depends on condition
R
WDTRMCLRRIPORBOR
bit 7STKOVF: Stack Overflow Flag bit
1 = A Stack Overflow occurred
0 = A Stack Overflow has not occurred or cleared by firmware
bit 6STKUNF: Stack Underflow Flag bit
1 = A Stack Underflow occurred
0 = A Stack Underflow has not occurred or cleared by firmware
bit 5Unimplemented: Read as ‘0’
bit 4R
bit 3RMCLR
bit 2RI: RESET Instruction Flag bit
bit 1POR
bit 0BOR
WDT: Watchdog Timer Reset Flag bit
1 = A Watchdog Timer Reset has not occurred or set to ‘1’ by firmware
0 = A Watchdog Timer Reset has occurred (cleared by hardware)
: MCLR Reset Flag bit
1 = A MCLR Reset has not occurred or set to ‘1’ by firmware
0 = A MCLR
1 = A RESET instruction has not been executed or set to ‘1’ by firmware
0 = A RESET instruction has been executed (cleared by hardware)
1 = No Power-on Reset occurred
0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)
1 = No Brown-out Reset occurred
0 = A Brown-out Reset occurred (must be set in software after a Power-on Reset or Brown-out Reset
The oscillator module has a wide variety of clock
sources and selection features that allow it to be used
in a wide range of applications while maximizing performance and minimizing power consumption. Figure 6-1
illustrates a block diagram of the oscillator module.
Clock sources can be supplied from external oscillators,
quartz crystal resonators, ceramic resonators and
Resistor-Capacitor (RC) circuits. In addition, the system
clock source can be supplied from one of two internal
oscillators and PLL circuits, with a choice of speeds
selectable via software. Additional clock features
include:
• Selectable system clock source between external
or internal sources via software.
• Two-Speed Start-up mode, which minimizes
latency between external oscillator start-up and
code execution.
• Fail-Safe Clock Monitor (FSCM) designed to
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch
automatically to the internal oscillator.
5.XT – Medium Gain Crystal or Ceramic Resonator
Oscillator mode (up to 4 MHz)
6.HS – High Gain Crystal or Ceramic Resonator
mode (4 MHz to 20 MHz)
7.RC – External Resistor-Capacitor (RC)
8.INTOSC – Internal oscillator (31 kHz to 32 MHz)
Clock Source modes are selected by the FOSC<2:0>
bits in the Configuration Words. The FOSC bits
determine the type of oscillator that will be used when
the device is first powered.
The EC clock mode relies on an external logic level
signal as the device clock source. The LP, XT, and HS
clock modes require an external crystal or resonator to
be connected to the device. Each mode is optimized for
a different frequency range. The RC clock mode
requires an external resistor and capacitor to set the
oscillator frequency.
The INTOSC internal oscillator block produces low,
medium, and high-frequency clock sources,
designated LFINTOSC, MFINTOSC and HFINTOSC.
(see Internal Oscillator Block, Figure 6-1). A wide
selection of device clock frequencies may be derived
from these three clock sources.
DS41675A-page 74Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
OSC1/CLKIN
OSC2/CLKOUT
Clock from
Ext. System
PIC
®
MCU
FOSC/4 or
I/O
(1)
Note 1:Output depends upon CLKOUTEN bit of the
Configuration Words.
6.2Clock Source Types
Clock sources can be classified as external or internal.
External clock sources rely on external circuitry for the
clock source to function. Examples are: oscillator
modules (EC mode), quartz crystal resonators or
ceramic resonators (LP, XT and HS modes) and
Resistor-Capacitor (RC) mode circuits.
Internal clock sources are contained within the
oscillator module. The internal oscillator block has two
internal oscillators and a dedicated Phase-Lock Loop
(HFPLL) that are used to generate three internal
system clock sources: the 16 MHz High-Frequency
Internal Oscillator (HFINTOSC), 500 kHz (MFINTOSC)
and the 31 kHz Low-Frequency Internal Oscillator
(LFINTOSC).
The system clock can be selected between external or
internal clock sources via the System Clock Select
(SCS) bits in the OSCCON register. See Section 6.3
“Clock Switching” for additional information.
6.2.1EXTERNAL CLOCK SOURCES
An external clock source can be used as the device
system clock by performing one of the following
actions:
• Program the FOSC<2:0> bits in the Configuration
Words to select an external clock source that will
be used as the default system clock upon a
device Reset.
• Write the SCS<1:0> bits in the OSCCON register
to switch the system clock source to:
- Timer1 oscillator during run-time, or
- An external clock source determined by the
value of the FOSC bits.
See Section 6.3 “Clock Switching”for more informa-
tion.
6.2.1.1EC Mode
The External Clock (EC) mode allows an externally
generated logic level signal to be the system clock
source. When operating in this mode, an external clock
source is connected to the OSC1 input.
OSC2/CLKOUT is available for general purpose I/O or
CLKOUT. Figure 6-2 shows the pin connections for EC
mode.
EC mode has three power modes to select from through
Configuration Words:
• High power, 4-32 MHz (FOSC = 111)
• Medium power, 0.5-4 MHz (FOSC = 110)
• Low power, 0-0.5 MHz (FOSC = 101)
The Oscillator Start-up Timer (OST) is disabled when
EC mode is selected. Therefore, there is no delay in
operation after a Power-on Reset (POR) or wake-up
from Sleep. Because the PIC
®
MCU design is fully
static, stopping the external clock input will have the
effect of halting the device while leaving all data intact.
Upon restarting the external clock, the device will
resume operation as if no time had elapsed.
FIGURE 6-2:EXTERNAL CLOCK (EC)
MODE OPERATION
6.2.1.2LP, XT, HS Modes
The LP, XT and HS modes support the use of quartz
crystal resonators or ceramic resonators connected to
OSC1 and OSC2 (Figure 6-3). The three modes select
a low, medium or high gain setting of the internal
inverter-amplifier to support various resonator types
and speed.
LP Oscillator mode selects the lowest gain setting of the
internal inverter-amplifier. LP mode current consumption
is the least of the three modes. This mode is designed to
drive only 32.768 kHz tuning-fork type crystals (watch
crystals).
XT Oscillator mode selects the intermediate gain
setting of the internal inverter-amplifier. XT mode
current consumption is the medium of the three modes.
This mode is best suited to drive resonators with a
medium drive level specification.
HS Oscillator mode selects the highest gain setting of the
internal inverter-amplifier. HS mode current consumption
is the highest of the three modes. This mode is best
suited for resonators that require a high drive setting.
Figure 6-3 and Figure 6-4 show typical circuits for
quartz crystal and ceramic resonators, respectively.
Note 1: A series resistor (RS) may be required for
quartz crystals with low drive level.
2: The value of R
F varies with the Oscillator mode
selected (typically between 2 M to 10 M.
C1
C2
Quartz
R
S
(1)
OSC1/CLKIN
RF
(2)
Sleep
To Internal
Logic
PIC® MCU
Crystal
OSC2/CLKOUT
Note 1: A series resistor (RS) may be required for
ceramic resonators with low drive level.
2: The value of R
F varies with the Oscillator mode
selected (typically between 2 M to 10 M.
3: An additional parallel feedback resistor (R
P)
may be required for proper ceramic resonator
operation.
C1
C2
Ceramic
R
S
(1)
OSC1/CLKIN
RF
(2)
Sleep
To Internal
Logic
PIC® MCU
RP
(3)
Resonator
OSC2/CLKOUT
FIGURE 6-3:QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
Note 1: Quartz crystal characteristics vary
according to type, package and
manufacturer. The user should consult the
manufacturer data sheets for specifications
and recommended application.
2: Always verify oscillator performance over
DD and temperature range that is
the V
expected for the application.
3: For oscillator design assistance, reference
the following Microchip Application Notes:
• AN826, “Crystal Oscillator Basics and
Crystal Selection for rfPIC
Devices” (DS00826)
• AN849, “Basic PIC
(DS00849)
• AN943, “Practical PICAnalysis and Design” (DS00943)
• AN949, “Making Your Oscillator Work”
(DS00949)
®
and PIC®
®
Oscillator Design”
®
Oscillator
FIGURE 6-4:CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
6.2.1.3Oscillator Start-up Timer (OST)
If the oscillator module is configured for LP, XT or HS
modes, the Oscillator Start-up Timer (OST) counts
1024 oscillations from OSC1. This occurs following a
Power-on Reset (POR) and when the Power-up Timer
(PWRT) has expired (if configured), or a wake-up from
Sleep. During this time, the program counter does not
increment and program execution is suspended,
unless either FSCM or Two-Speed Start-Up are
enabled. In this case, code will continue to execute at
the selected INTOSC frequency while the OST is
counting (in GC). The OST ensures that the oscillator
circuit, using a quartz crystal resonator or ceramic
resonator, has started and is providing a stable system
clock to the oscillator module.
In order to minimize latency between external oscillator
start-up and code execution, the Two-Speed Clock
Start-up mode can be selected (see Section 6.4
“Two-Speed Clock Start-up Mode”).
DS41675A-page 76Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
C1
C2
32.768 kHz
T1OSI
To Internal
Logic
PIC® MCU
Crystal
T1OSO
Quartz
6.2.1.44x PLL
The oscillator module contains a 4x PLL that can be
used with both external and internal clock sources to
provide a system clock source. The input frequency for
the 4x PLL must fall within specifications. See the PLL
Clock Timing Specifications in Section 31.0
“Electrical Specifications”.
The 4x PLL may be enabled for use by one of two
methods:
1. Program the PLLEN bit in Configuration Words
to a ‘1’.
2.Write the SPLLEN bit in the OSCCON register to
a ‘1’. If the PLLEN bit in Configuration Words is
programmed to a ‘1’, then the value of SPLLEN
is ignored.
6.2.1.5TIMER1 Oscillator
The Timer1 oscillator is a separate crystal oscillator
that is associated with the Timer1 peripheral. It is
optimized for timekeeping operations with a 32.768
kHz crystal connected between the T1OSO and T1OSI
device pins.
The Timer1 oscillator can be used as an alternate
system clock source and can be selected during
run-time using clock switching. Refer to Section 6.3
“Clock Switching” for more information.
Note 1: Quartz crystal characteristics vary
according to type, package and
manufacturer. The user should consult the
manufacturer data sheets for specifications
and recommended application.
2: Always verify oscillator performance over
DD and temperature range that is
the V
expected for the application.
3: For oscillator design assistance, reference
the following Microchip Application Notes:
• AN826, “Crystal Oscillator Basics and
Crystal Selection for rfPIC
®
and PIC®
Devices” (DS00826)
®
• AN849, “Basic PIC
Oscillator Design”
(DS00849)
®
• AN943, “Practical PIC
Oscillator
Analysis and Design” (DS00943)
• AN949, “Making Your Oscillator Work”
(DS00949)
• TB097, “Interfacing a Micro Crystal
MS1V-T1K 32.768 kHz Tuning Fork
Crystal to a PIC16F690/SS” (DS91097)
• AN1288, “Design Practices for
Low-Power External Oscillators”
The external Resistor-Capacitor (RC) modes support
the use of an external RC circuit. This allows the
designer maximum flexibility in frequency choice while
keeping costs to a minimum when clock accuracy is not
required.
The RC circuit connects to OSC1. OSC2/CLKOUT is
available for general purpose I/O or CLKOUT. The
function of the OSC2/CLKOUT pin is determined by the
CLKOUTEN
bit in Configuration Words.
Figure 6-6 shows the external RC mode connections.
FIGURE 6-6:EXTERNAL RC MODES
The RC oscillator frequency is a function of the supply
voltage, the resistor (R
and the operating temperature. Other factors affecting
the oscillator frequency are:
• threshold voltage variation
• component tolerances
• packaging variations in capacitance
The user also needs to take into account variation due
to tolerance of external RC components used.
EXT) and capacitor (CEXT) values
6.2.2INTERNAL CLOCK SOURCES
The device may be configured to use the internal
oscillator block as the system clock by performing one
of the following actions:
• Program the FOSC<2:0> bits in Configuration
Words to select the INTOSC clock source, which
will be used as the default system clock upon a
device Reset.
• Write the SCS<1:0> bits in the OSCCON register
to switch the system clock source to the internal
oscillator during run-time. See Section 6.3
“Clock Switching”for more information.
In INTOSC mode, OSC1/CLKIN is available for general
purpose I/O. OSC2/CLKOUT is available for general
purpose I/O or CLKOUT.
The function of the OSC2/CLKOUT pin is determined
by the CLKOUTEN
The internal oscillator block has two independent
oscillators and a dedicated Phase-Lock Loop, HFPLL
that can produce one of three internal system clock
sources.
1. The HFINTOSC (High-Frequency Internal
Oscillator) is factory calibrated and operates at
16 MHz. The HFINTOSC source is generated
from the 500 kHz MFINTOSC source and the
dedicated Phase-Lock Loop, HFPLL. The
frequency of the HFINTOSC can be
user-adjusted via software using the OSCTUNE
register (Register 6-3).
2.The MFINTOSC (Medium-Frequency Internal
Oscillator) is factory calibrated and operates at
500 kHz. The frequency of the MFINTOSC can
be user-adjusted via software using the
OSCTUNE register (Register 6-3).
3. The LFINTOSC (Low-Frequency Internal
Oscillator) is uncalibrated and operates at
31 kHz.
bit in Configuration Words.
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PIC16(L)F1788/9
6.2.2.1HFINTOSC
The High-Frequency Internal Oscillator (HFINTOSC) is
a factory calibrated 16 MHz internal clock source. The
frequency of the HFINTOSC can be altered via
software using the OSCTUNE register (Register 6-3).
The output of the HFINTOSC connects to a postscaler
and multiplexer (see Figure 6-1). One of multiple
frequencies derived from the HFINTOSC can be
selected via software using the IRCF<3:0> bits of the
OSCCON register. See Section 6.2.2.7 “Internal
Oscillator Clock Switch Timing” for more information.
The HFINTOSC is enabled by:
• Configure the IRCF<3:0> bits of the OSCCON
register for the desired HF frequency, and
•FOSC<2:0> = 100, or
• Set the System Clock Source (SCS) bits of the
OSCCON register to ‘1x’
A fast start-up oscillator allows internal circuits to power
up and stabilize before switching to HFINTOSC.
The High-Frequency Internal Oscillator Ready bit
(HFIOFR) of the OSCSTAT register indicates when the
HFINTOSC is running.
The High-Frequency Internal Oscillator Status Locked
bit (HFIOFL) of the OSCSTAT register indicates when
the HFINTOSC is running within 2% of its final value.
The High-Frequency Internal Oscillator Stable bit
(HFIOFS) of the OSCSTAT register indicates when the
HFINTOSC is running within 0.5% of its final value.
6.2.2.2MFINTOSC
The Medium-Frequency Internal Oscillator
(MFINTOSC) is a factory calibrated 500 kHz internal
clock source. The frequency of the MFINTOSC can be
altered via software using the OSCTUNE register
(Register 6-3).
The output of the MFINTOSC connects to a postscaler
and multiplexer (see Figure 6-1). One of nine
frequencies derived from the MFINTOSC can be
selected via software using the IRCF<3:0> bits of the
OSCCON register. See Section 6.2.2.7 “Internal
Oscillator Clock Switch Timing” for more information.
The MFINTOSC is enabled by:
• Configure the IRCF<3:0> bits of the OSCCON
register for the desired HF frequency, and
•FOSC<2:0> = 100, or
• Set the System Clock Source (SCS) bits of the
OSCCON register to ‘1x’
The Medium-Frequency Internal Oscillator Ready bit
(MFIOFR) of the OSCSTAT register indicates when the
MFINTOSC is running.
6.2.2.3Internal Oscillator Frequency
Adjustment
The 500 kHz internal oscillator is factory calibrated.
This internal oscillator can be adjusted in software by
writing to the OSCTUNE register (Register 6-3). Since
the HFINTOSC and MFINTOSC clock sources are
derived from the 500 kHz internal oscillator a change in
the OSCTUNE register value will apply to both.
The default value of the OSCTUNE register is ‘0’. The
value is a 6-bit two’s complement number. A value of
1Fh will provide an adjustment to the maximum
frequency. A value of 20h will provide an adjustment to
the minimum frequency.
When the OSCTUNE register is modified, the oscillator
frequency will begin shifting to the new frequency. Code
execution continues during this shift. There is no
indication that the shift has occurred.
OSCTUNE does not affect the LFINTOSC frequency.
Operation of features that depend on the LFINTOSC
clock source frequency, such as the Power-up Timer
(PWRT), Watchdog Timer (WDT), Fail-Safe Clock
Monitor (FSCM) and peripherals, are not affected by the
change in frequency.
6.2.2.4LFINTOSC
The Low-Frequency Internal Oscillator (LFINTOSC) is
an uncalibrated 31 kHz internal clock source.
The output of the LFINTOSC connects to a multiplexer
(see Figure 6-1). Select 31 kHz, via software, using the
IRCF<3:0> bits of the OSCCON register. See
Section 6.2.2.7 “Internal Oscillator Clock Switch
Timing” for more information. The LFINTOSC is also
the frequency for the Power-up Timer (PWRT),
Watchdog Timer (WDT) and Fail-Safe Clock Monitor
(FSCM).
The LFINTOSC is enabled by selecting 31 kHz
(IRCF<3:0> bits of the OSCCON register = 000) as the
system clock source (SCS bits of the OSCCON
register = 1x), or when any of the following are
enabled:
• Configure the IRCF<3:0> bits of the OSCCON
register for the desired LF frequency, and
•FOSC<2:0> = 100, or
• Set the System Clock Source (SCS) bits of the
OSCCON register to ‘1x’
Peripherals that use the LFINTOSC are:
• Power-up Timer (PWRT)
• Watchdog Timer (WDT)
• Fail-Safe Clock Monitor (FSCM)
The Low-Frequency Internal Oscillator Ready bit
(LFIOFR) of the OSCSTAT register indicates when the
LFINTOSC is running.
The system clock speed can be selected via software
using the Internal Oscillator Frequency Select bits
IRCF<3:0> of the OSCCON register.
The output of the 16 MHz HFINTOSC, 500 kHz
MFINTOSC, and 31 kHz LFINTOSC connects to a
postscaler and multiplexer (see Figure 6-1). The
Internal Oscillator Frequency Select bits IRCF<3:0> of
the OSCCON register select the frequency output of the
internal oscillators. One of the following frequencies
can be selected via software:
- 32 MHz (requires 4x PLL)
-16 MHz
-8 MHz
-4 MHz
-2 MHz
-1 MHz
- 500 kHz (default after Reset)
- 250 kHz
- 125 kHz
- 62.5 kHz
- 31.25 kHz
- 31 kHz (LFINTOSC)
Note:Following any Reset, the IRCF<3:0> bits
of the OSCCON register are set to ‘0111’
and the frequency selection is set to
500 kHz. The user can modify the IRCF
bits to select a different frequency.
6.2.2.632 MHz Internal Oscillator
Frequency Selection
The Internal Oscillator Block can be used with the
4x PLL associated with the External Oscillator Block to
produce a 32 MHz internal system clock source. The
following settings are required to use the 32 MHz
internal clock source:
• The FOSC bits in Configuration Words must be
set to use the INTOSC source as the device
system clock (FOSC<2:0> = 100).
• The SCS bits in the OSCCON register must be
cleared to use the clock determined by
FOSC<2:0> in Configuration Words
(SCS<1:0> = 00).
• The IRCF bits in the OSCCON register must be
set to the 8 MHz or 16 MHz HFINTOSC set to use
(IRCF<3:0> = 111x).
• The SPLLEN bit in the OSCCON register must be
set to enable the 4x PLL, or the PLLEN bit of the
Configuration Words must be programmed to a
‘1’.
Note:When using the PLLEN bit of the
Configuration Words, the 4x PLL cannot
be disabled by software and the SPLLEN
option will not be available.
The 4x PLL is not available for use with the internal
oscillator when the SCS bits of the OSCCON register
are set to ‘1x’. The SCS bits must be set to ‘00’ to use
the 4x PLL with the internal oscillator.
The IRCF<3:0> bits of the OSCCON register allow
duplicate selections for some frequencies. These
duplicate choices can offer system design trade-offs.
Lower power consumption can be obtained when
changing oscillator sources for a given frequency.
Faster transition times can be obtained between
frequency changes that use the same oscillator source.
DS41675A-page 80Preliminary 2013 Microchip Technology Inc.
6.2.2.7Internal Oscillator Clock Switch
Timing
When switching between the HFINTOSC, MFINTOSC
and the LFINTOSC, the new oscillator may already be
shut down to save power (see Figure 6-7). If this is the
case, there is a delay after the IRCF<3:0> bits of the
OSCCON register are modified before the frequency
selection takes place. The OSCSTAT register will
reflect the current active status of the HFINTOSC,
MFINTOSC and LFINTOSC oscillators. The sequence
of a frequency selection is as follows:
1.IRCF<3:0> bits of the OSCCON register are
modified.
2. If the new clock is shut down, a clock start-up
delay is started.
3. Clock switch circuitry waits for a falling edge of
the current clock.
4.The current clock is held low and the clock
switch circuitry waits for a rising edge in the new
clock.
5. The new clock is now active.
6.The OSCSTAT register is updated as required.
7.Clock switch is complete.
See Figure 6-7 for more details.
If the internal oscillator speed is switched between two
clocks of the same source, there is no start-up delay
before the new frequency is selected. Clock switching
time delays are shown in Table 6-1.
Start-up delay specifications are located in the
oscillator tables of Section 31.0 “Electrical
DS41675A-page 82Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
6.3Clock Switching
The system clock source can be switched between
external and internal clock sources via software using
the System Clock Select (SCS) bits of the OSCCON
register. The following clock sources can be selected
using the SCS bits:
• Default system oscillator determined by FOSC
bits in Configuration Words
• Timer1 32 kHz crystal oscillator
• Internal Oscillator Block (INTOSC)
6.3.1SYSTEM CLOCK SELECT (SCS)
BITS
The System Clock Select (SCS) bits of the OSCCON
register selects the system clock source that is used for
the CPU and peripherals.
• When the SCS bits of the OSCCON register = 00,
the system clock source is determined by the
value of the FOSC<2:0> bits in the Configuration
Words.
• When the SCS bits of the OSCCON register = 01,
the system clock source is the Timer1 oscillator.
• When the SCS bits of the OSCCON register = 1x,
the system clock source is chosen by the internal
oscillator frequency selected by the IRCF<3:0>
bits of the OSCCON register. After a Reset, the
SCS bits of the OSCCON register are always
cleared.
Note:Any automatic clock switch, which may
occur from Two-Speed Start-up or
Fail-Safe Clock Monitor, does not update
the SCS bits of the OSCCON register. The
user can monitor the OSTS bit of the
OSCSTAT register to determine the
current system clock source.
6.3.3TIMER1 OSCILLATOR
The Timer1 oscillator is a separate crystal oscillator
associated with the Timer1 peripheral. It is optimized
for timekeeping operations with a 32.768 kHz crystal
connected between the T1OSO and T1OSI device
pins.
The Timer1 oscillator is enabled using the T1OSCEN
control bit in the T1CON register. See Section 23.0
“Timer1 Module with Gate Control” for more
information about the Timer1 peripheral.
6.3.4TIMER1 OSCILLATOR READY
(T1OSCR) BIT
The user must ensure that the Timer1 oscillator is
ready to be used before it is selected as a system clock
source. The Timer1 Oscillator Ready (T1OSCR) bit of
the OSCSTAT register indicates whether the Timer1
oscillator is ready to be used. After the T1OSCR bit is
set, the SCS bits can be configured to select the
Timer1 oscillator.
When switching between clock sources, a delay is
required to allow the new clock to stabilize. These
oscillator delays are shown in Table 6-1.
6.3.2OSCILLATOR START-UP TIMER
STATUS (OSTS) BIT
The Oscillator Start-up Timer Status (OSTS) bit of the
OSCSTAT register indicates whether the system clock
is running from the external clock source, as defined by
the FOSC<2:0> bits in the Configuration Words, or
from the internal clock source. In particular, OSTS
indicates that the Oscillator Start-up Timer (OST) has
timed out for LP, XT or HS modes. The OST does not
reflect the status of the Timer1 oscillator.
Two-Speed Start-up mode provides additional power
savings by minimizing the latency between external
oscillator start-up and code execution. In applications
that make heavy use of the Sleep mode, Two-Speed
Start-up will remove the external oscillator start-up
time from the time spent awake and can reduce the
overall power consumption of the device. This mode
allows the application to wake-up from Sleep, perform
a few instructions using the INTOSC internal oscillator
block as the clock source and go back to Sleep without
waiting for the external oscillator to become stable.
Two-Speed Start-up provides benefits when the oscillator module is configured for LP, XT or HS modes.
The Oscillator Start-up Timer (OST) is enabled for
these modes and must count 1024 oscillations before
the oscillator can be used as the system clock source.
If the oscillator module is configured for any mode
other than LP, XT or HS mode, then Two-Speed
Start-up is disabled. This is because the external clock
oscillator does not require any stabilization time after
POR or an exit from Sleep.
If the OST count reaches 1024 before the device
enters Sleep mode, the OSTS bit of the OSCSTAT
register is set and program execution switches to the
external oscillator. However, the system may never
operate from the external oscillator if the time spent
awake is very short.
Note:Executing a SLEEP instruction will abort
the oscillator start-up time and will cause
the OSTS bit of the OSCSTAT register to
remain clear.
6.4.1TWO-SPEED START-UP MODE
CONFIGURATION
Two-Speed Start-up mode is configured by the
following settings:
• IESO (of the Configuration Words) = 1;
Internal/External Switchover bit (Two-Speed
Start-up mode enabled).
• SCS (of the OSCCON register) = 00.
• FOSC<2:0> bits in the Configuration Words
configured for LP, XT or HS mode.
Two-Speed Start-up mode is entered after:
• Power-on Reset (POR) and, if enabled, after
Power-up Timer (PWRT) has expired, or
• Wake-up from Sleep.
TABLE 6-1:OSCILLATOR SWITCHING DELAYS
Switch FromSwitch ToFrequencyOscillator Delay
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
31 kHz
31.25 kHz-500 kHz
Oscillator Warm-up Delay (T
31.25kHz-16MHz
DC – 32 MHz2 cycles
DC – 32 MHz1 cycle of each
32 kHz-20 MHz1024 Clock Cycles (OST)
31.25 kHz-500 kHz
31.25kHz-16MHz
2 s (approx.)
31 kHz1 cycle of each
WARM)
LFINTOSC
Sleep/POR
MFINTOSC
HFINTOSC
Sleep/POREC, RC
LFINTOSCEC, RC
Sleep/POR
Any clock source
Timer1 Oscillator
LP, XT, HS
MFINTOSC
HFINTOSC
Any clock sourceLFINTOSC
Any clock sourceTimer1 Oscillator32 kHz1024 Clock Cycles (OST)
PLL inactivePLL active16-32 MHz2 ms (approx.)
Note 1: PLL inactive.
DS41675A-page 84Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
011022 1023
PC + 1
TOSTT
INTOSC
OSC1
OSC2
Program Counter
System Clock
PC - N
PC
6.4.2TWO-SPEED START-UP
SEQUENCE
1. Wake-up from Power-on Reset or Sleep.
2.Instructions begin execution by the internal
oscillator at the frequency set in the IRCF<3:0>
bits of the OSCCON register.
3. OST enabled to count 1024 clock cycles.
4.OST timed out, wait for falling edge of the
internal oscillator.
5.OSTS is set.
6. System clock held low until the next falling edge
of new clock (LP, XT or HS mode).
7. System clock is switched to external clock
source.
FIGURE 6-8:TWO-SPEED START-UP
6.4.3CHECKING TWO-SPEED CLOCK
STATUS
Checking the state of the OSTS bit of the OSCSTAT
register will confirm if the microcontroller is running
from the external clock source, as defined by the
FOSC<2:0> bits in the Configuration Words, or the
internal oscillator.
The Fail-Safe Clock Monitor (FSCM) allows the device
to continue operating should the external oscillator fail.
The FSCM can detect oscillator failure any time after
the Oscillator Start-up Timer (OST) has expired. The
FSCM is enabled by setting the FCMEN bit in the
Configuration Words. The FSCM is applicable to all
external Oscillator modes (LP, XT, HS, EC, Timer1
Oscillator and RC).
FIGURE 6-9:FSCM BLOCK DIAGRAM
6.5.1FAIL-SAFE DETECTION
The FSCM module detects a failed oscillator by
comparing the external oscillator to the FSCM sample
clock. The sample clock is generated by dividing the
LFINTOSC by 64. See Figure 6-9. Inside the fail
detector block is a latch. The external clock sets the
latch on each falling edge of the external clock. The
sample clock clears the latch on each rising edge of the
sample clock. A failure is detected when an entire
half-cycle of the sample clock elapses before the
external clock goes low.
6.5.3FAIL-SAFE CONDITION CLEARING
The Fail-Safe condition is cleared after a Reset,
executing a SLEEP instruction or changing the SCS bits
of the OSCCON register. When the SCS bits are
changed, the OST is restarted. While the OST is
running, the device continues to operate from the
INTOSC selected in OSCCON. When the OST times
out, the Fail-Safe condition is cleared after successfully
switching to the external clock source. The OSFIF bit
should be cleared prior to switching to the external
clock source. If the Fail-Safe condition still exists, the
OSFIF flag will again become set by hardware.
6.5.4RESET OR WAKE-UP FROM SLEEP
The FSCM is designed to detect an oscillator failure
after the Oscillator Start-up Timer (OST) has expired.
The OST is used after waking up from Sleep and after
any type of Reset. The OST is not used with the EC or
RC Clock modes so that the FSCM will be active as
soon as the Reset or wake-up has completed. When
the FSCM is enabled, the Two-Speed Start-up is also
enabled. Therefore, the device will always be executing
code while the OST is operating.
Note:Due to the wide range of oscillator start-up
times, the Fail-Safe circuit is not active
during oscillator start-up (i.e., after exiting
Reset or Sleep). After an appropriate
amount of time, the user should check the
Status bits in the OSCSTAT register to
verify the oscillator start-up and that the
system clock switchover has successfully
completed.
6.5.2FAIL-SAFE OPERATION
When the external clock fails, the FSCM switches the
device clock to an internal clock source and sets the bit
flag OSFIF of the PIR2 register. Setting this flag will
generate an interrupt if the OSFIE bit of the PIE2
register is also set. The device firmware can then take
steps to mitigate the problems that may arise from a
failed clock. The system clock will continue to be
sourced from the internal clock source until the device
firmware successfully restarts the external oscillator
and switches back to external operation.
The internal clock source chosen by the FSCM is
determined by the IRCF<3:0> bits of the OSCCON
register. This allows the internal oscillator to be
configured before a failure occurs.
DS41675A-page 86Preliminary 2013 Microchip Technology Inc.
FIGURE 6-10:FSCM TIMING DIAGRAM
OSCFIF
System
Clock
Output
Sample Clock
Failure
Detected
Oscillator
Failure
Note:The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is cleared
bit 7SPLLEN: Software PLL Enable bit
If PLLEN in Configuration Words =
SPLLEN bit is ignored. 4x PLL is always enabled (subject to oscillator requirements)
If PLLEN in Configuration Words = 0:
1 = 4x PLL Is enabled
0 = 4x PLL is disabled
bit 6-3IRCF<3:0>: Internal Oscillator Frequency Select bits
bit 2Unimplemented: Read as ‘0’
bit 1-0SCS<1:0>: System Clock Select bits
1x = Internal oscillator block
01 = Timer1 oscillator
00 = Clock determined by FOSC<2:0> in Configuration Words
(1)
(1)
(1)
(1)
1:
(2)
(2)
—
SCS<1:0>
Note 1: Duplicate frequency derived from HFINTOSC.
2: 32 MHz when SPLLEN bit is set. Refer to Section 6.2.2.6 “32 MHz Internal Oscillator Frequency
Selection”.
DS41675A-page 88Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
REGISTER 6-2:OSCSTAT: OSCILLATOR STATUS REGISTER
R-1/qR-0/qR-q/qR-0/qR-0/qR-q/qR-0/0R-0/q
T1OSCRPLLROSTSHFIOFRHFIOFLMFIOFRLFIOFRHFIOFS
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is clearedq = Conditional
bit 7T1OSCR: Timer1 Oscillator Ready bit
If T1OSCEN =
1 = Timer1 oscillator is ready
0 = Timer1 oscillator is not ready
If T1OSCEN =
1 = Timer1 clock source is always ready
bit 6PLLR 4x PLL Ready bit
1 = 4x PLL is ready
0 = 4x PLL is not ready
bit 5OSTS: Oscillator Start-up Timer Status bit
1 = Running from the clock defined by the FOSC<2:0> bits of the Configuration Words
0 = Running from an internal oscillator (FOSC<2:0> = 100)
bit 4HFIOFR: High-Frequency Internal Oscillator Ready bit
1 = HFINTOSC is ready
0 = HFINTOSC is not ready
bit 3HFIOFL: High-Frequency Internal Oscillator Locked bit
1 = HFINTOSC is at least 2% accurate
0 = HFINTOSC is not 2% accurate
bit 2MFIOFR: Medium-Frequency Internal Oscillator Ready bit
1 = MFINTOSC is ready
0 = MFINTOSC is not ready
bit 1LFIOFR: Low-Frequency Internal Oscillator Ready bit
1 = LFINTOSC is ready
0 = LFINTOSC is not ready
bit 0HFIOFS: High-Frequency Internal Oscillator Stable bit
1 = HFINTOSC is at least 0.5% accurate
0 = HFINTOSC is not 0.5% accurate
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is cleared
bit 7-6Unimplemented: Read as ‘0’
bit 5-0TUN<5:0>: Frequency Tuning bits
100000 = Minimum frequency
•
•
•
111111 =
000000 = Oscillator module is running at the factory-calibrated frequency
000001 =
•
•
•
011110 =
011111 = Maximum frequency
TABLE 6-2:SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES
Legend:— = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources.
13:8
7:0
——FCMENIESOCLKOUTENBOREN<1:0>CPD
CPMCLREPWRTEWDTE<1:0>FOSC<2:0>
Register
on Page
225
60
DS41675A-page 90Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
7.0REFERENCE CLOCK MODULE
The reference clock module provides the ability to send
a divided clock to the clock output pin of the device
(CLKR). This module is available in all oscillator configurations and allows the user to select a greater range
of clock submultiples to drive external devices in the
application. The reference clock module includes the
following features:
• System clock is the source
• Available in all oscillator configurations
• Programmable clock divider
• Output enable to a port pin
• Selectable duty cycle
• Slew rate control
The reference clock module is controlled by the
CLKRCON register (Register 7-1) and is enabled when
setting the CLKREN bit. To output the divided clock
signal to the CLKR port pin, the CLKROE bit must be
set. The CLKRDIV<2:0> bits enable the selection of
eight different clock divider options. The
CLKRDC<1:0> bits can be used to modify the duty
cycle of the output clock
slew rate limiting.
Note 1: If the base clock rate is selected without
a divider, the output clock will always
have a duty cycle equal to that of the
source clock, unless a 0% duty cycle is
selected. If the clock divider is set to base
clock/2, then 25% and 75% duty cycle
accuracy will be dependent upon the
source clock.
(1)
. The CLKRSLR bit controls
7.3Conflicts with the CLKR Pin
There are two cases when the reference clock output
signal cannot be output to the CLKR pin, if:
• LP, XT or HS Oscillator mode is selected.
• CLKOUT function is enabled.
7.3.1OSCILLATOR MODES
If LP, XT or HS oscillator modes are selected, the
OSC2/CLKR pin must be used as an oscillator input pin
and the CLKR output cannot be enabled. See
Section 6.2 “Clock Source Types”for more informa-
tion on different oscillator modes.
7.3.2CLKOUT FUNCTION
The CLKOUT function has a higher priority than the
reference clock module. Therefore, if the CLKOUT
function is enabled by the CLKOUTEN bit in Configuration Words, F
pin. Reference Section 4.0 “Device Configuration”
for more information.
OSC/4 will always be output on the port
7.4Operation During Sleep
As the reference clock module relies on the system
clock as its source, and the system clock is disabled in
Sleep, the module does not function in Sleep, even if
an external clock source or the Timer1 clock source is
configured as the system clock. The module outputs
will remain in their current state until the device exits
Sleep.
7.1Slew Rate
The slew rate limitation on the output port pin can be
disabled. The slew rate limitation is removed by
clearing the CLKRSLR bit in the CLKRCON register.
7.2Effects of a Reset
Upon any device Reset, the reference clock module is
disabled. The user’s firmware is responsible for
initializing the module before enabling the output. The
registers are reset to their default values.
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is cleared
bit 7CLKREN: Reference Clock Module Enable bit
1 = Reference clock module is enabled
0 = Reference clock module is disabled
bit 6CLKROE: Reference Clock Output Enable bit
1 = Reference clock output is enabled on CLKR pin
0 = Reference clock output disabled on CLKR pin
bit 5CLKRSLR: Reference Clock Slew Rate Control Limiting Enable bit
1 = Slew rate limiting is enabled
0 = Slew rate limiting is disabled
bit 4-3CLKRDC<1:0>: Reference Clock Duty Cycle bits
11 = Clock outputs duty cycle of 75%
10 = Clock outputs duty cycle of 50%
01 = Clock outputs duty cycle of 25%
00 = Clock outputs duty cycle of 0%
bit 2-0CLKRDIV<2:0> Reference Clock Divider bits
111 = Base clock value divided by 128
110 = Base clock value divided by 64
101 = Base clock value divided by 32
100 = Base clock value divided by 16
011 = Base clock value divided by 8
010 = Base clock value divided by 4
001 = Base clock value divided by 2
000 = Base clock value
Note 1: In this mode, the 25% and 75% duty cycle accuracy will be dependent on the source clock duty cycle.
2: In this mode, the duty cycle will always be equal to the source clock duty cycle, unless a duty cycle of 0%
is selected.
(2)
(1)
DS41675A-page 92Preliminary 2013 Microchip Technology Inc.
PIC16(L)F1788/9
TABLE 7-1:SUMMARY OF REGISTERS ASSOCIATED WITH REFERENCE CLOCK SOURCES
NameBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
CLKRCONCLKRENCLKROE CLKRSLRCLKRDC<1:0>
Legend:— = unimplemented locations read as ‘0’. Shaded cells are not used by reference clock sources.
CLKRDIV<2:0>
TABLE 7-2:SUMMARY OF CONFIGURATION WORD WITH REFERENCE CLOCK SOURCES
DS41675A-page 94Preliminary 2013 Microchip Technology Inc.
8.0INTERRUPTS
TMR0IF
TMR0IE
INTF
INTE
IOCIF
IOCIE
Interrupt
to CPU
Wake-up
(If in Sleep mode)
GIE
(TMR1IF) PIR1<0>
PIRn<7>
PEIE
(TMR1IE) PIE1<0>
Peripheral Interrupts
PIEn<7>
The interrupt feature allows certain events to preempt
normal program flow. Firmware is used to determine
the source of the interrupt and act accordingly. Some
interrupts can be configured to wake the MCU from
Sleep mode.
This chapter contains the following information for
Interrupts:
• Operation
• Interrupt Latency
• Interrupts During Sleep
•INT Pin
• Automatic Context Saving
Many peripherals produce interrupts. Refer to the
corresponding chapters for details.
A block diagram of the interrupt logic is shown in
Interrupts are disabled upon any device Reset. They
are enabled by setting the following bits:
• GIE bit of the INTCON register
• Interrupt Enable bit(s) for the specific interrupt
event(s)
• PEIE bit of the INTCON register (if the Interrupt
Enable bit of the interrupt event is contained in the
PIE1 or PIE2 registers)
The INTCON, PIR1 and PIR2 registers record individual interrupts via interrupt flag bits. Interrupt flag bits will
be set, regardless of the status of the GIE, PEIE and
individual interrupt enable bits.
The following events happen when an interrupt event
occurs while the GIE bit is set:
• Current prefetched instruction is flushed
• GIE bit is cleared
• Current Program Counter (PC) is pushed onto the
stack
• Critical registers are automatically saved to the
shadow registers (See “Section 8.5 “Automatic
Context Saving”.”)
• PC is loaded with the interrupt vector 0004h
The firmware within the Interrupt Service Routine (ISR)
should determine the source of the interrupt by polling
the interrupt flag bits. The interrupt flag bits must be
cleared before exiting the ISR to avoid repeated
interrupts. Because the GIE bit is cleared, any interrupt
that occurs while executing the ISR will be recorded
through its interrupt flag, but will not cause the
processor to redirect to the interrupt vector.
The RETFIE instruction exits the ISR by popping the
previous address from the stack, restoring the saved
context from the shadow registers and setting the GIE
bit.
For additional information on a specific interrupt’s
operation, refer to its peripheral chapter.
8.2Interrupt Latency
Interrupt latency is defined as the time from when the
interrupt event occurs to the time code execution at the
interrupt vector begins. The latency for synchronous
interrupts is three or four instruction cycles. For
asynchronous interrupts, the latency is three to five
instruction cycles, depending on when the interrupt
occurs. See Figure 8-2 and Figure 8.3 for more details.
Note 1: Individual interrupt flag bits are set,
regardless of the state of any other
enable bits.
2: All interrupts will be ignored while the GIE
bit is cleared. Any interrupt occurring
while the GIE bit is clear will be serviced
when the GIE bit is set again.
DS41675A-page 96Preliminary 2013 Microchip Technology Inc.
Latency is the same whether Inst (PC) is a single cycle or a 2-cycle instruction.
3: CLKOUT not available in all oscillator modes.
4: For minimum width of INT pulse, refer to AC specifications in Section 31.0 “Electrical Specifications””.
5: INTF is enabled to be set any time during the Q4-Q1 cycles.
(1)
(2)
(3)
(4)
(5)
(1)
FIGURE 8-3:INT PIN INTERRUPT TIMING
DS41675A-page 98Preliminary 2013 Microchip Technology Inc.
8.3Interrupts During Sleep
Some interrupts can be used to wake from Sleep. To
wake from Sleep, the peripheral must be able to
operate without the system clock. The interrupt source
must have the appropriate Interrupt Enable bit(s) set
prior to entering Sleep.
On waking from Sleep, if the GIE bit is also set, the
processor will branch to the interrupt vector. Otherwise,
the processor will continue executing instructions after
the SLEEP instruction. The instruction directly after the
SLEEP instruction will always be executed before
branching to the ISR. Refer to Section 9.0
“Power-Down Mode (Sleep)” for more details.
8.4INT Pin
The INT pin can be used to generate an asynchronous
edge-triggered interrupt. This interrupt is enabled by
setting the INTE bit of the INTCON register. The
INTEDG bit of the OPTION_REG register determines on
which edge the interrupt will occur. When the INTEDG
bit is set, the rising edge will cause the interrupt. When
the INTEDG bit is clear, the falling edge will cause the
interrupt. The INTF bit of the INTCON register will be set
when a valid edge appears on the INT pin. If the GIE and
INTE bits are also set, the processor will redirect
program execution to the interrupt vector.
PIC16(L)F1788/9
8.5Automatic Context Saving
Upon entering an interrupt, the return PC address is
saved on the stack. Additionally, the following registers
are automatically saved in the shadow registers:
• W register
• STATUS register (except for TO
• BSR register
• FSR registers
• PCLATH register
Upon exiting the Interrupt Service Routine, these registers are automatically restored. Any modifications to
these registers during the ISR will be lost. If modifications to any of these registers are desired, the corresponding shadow register should be modified and the
value will be restored when exiting the ISR. The
shadow registers are available in Bank 31 and are
readable and writable. Depending on the user’s
application, other registers may also need to be saved.
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
u = Bit is unchangedx = Bit is unknown-n/n = Value at POR and BOR/Value at all other Resets
‘1’ = Bit is set‘0’ = Bit is cleared
bit 7GIE: Global Interrupt Enable bit
1 = Enables all active interrupts
0 = Disables all interrupts
bit 6PEIE: Peripheral Interrupt Enable bit
1 = Enables all active peripheral interrupts
0 = Disables all peripheral interrupts
bit 5TMR0IE: Timer0 Overflow Interrupt Enable bit
1 = Enables the Timer0 interrupt
0 = Disables the Timer0 interrupt
bit 4INTE: INT External Interrupt Enable bit
1 = Enables the INT external interrupt
0 = Disables the INT external interrupt
bit 3IOCIE: Interrupt-on-Change Enable bit
1 = Enables the interrupt-on-change
0 = Disables the interrupt-on-change
bit 2TMR0IF: Timer0 Overflow Interrupt Flag bit
1 = TMR0 register has overflowed
0 = TMR0 register did not overflow
bit 1INTF: INT External Interrupt Flag bit
1 = The INT external interrupt occurred
0 = The INT external interrupt did not occur
bit 0IOCIF: Interrupt-on-Change Interrupt Flag bit
1 = When at least one of the interrupt-on-change pins changed state
0 = None of the interrupt-on-change pins have changed state
(1)
(1)
Note 1: The IOCIF Flag bit is read-only and cleared when all the interrupt-on-change flags in the IOCBF register
Note:Interrupt flag bits are set when an interrupt
DS41675A-page 100Preliminary 2013 Microchip Technology Inc.
have been cleared by software.
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Enable bit, GIE, of the INTCON register.
User software should ensure the
appropriate interrupt flag bits are clear
prior to enabling an interrupt.
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