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EM78P451
OTP ROM
1. GENERAL DESCRIPTION
The EM78P451 is an 8-bit microprocessor designed and developed with low-power, high speed CMOS
technology. Its operational kernel is implemented with RISC-like architecture and is available in the mask
ROM version. The one time programmable (OTP) version is flexible, both in mass production or
engineering test stages. OTP provide users with unlimited volume with favorable price opportunities. This
device is equipped with the Serial Peripheral Interface (SPI) function and an easy-implemented RS-232.
The EM78P451 is very suitable for wired communication. Only 58 easy-to-learn instructions are needed
and user’s program can be emulated with EMC In-Circuit Emulator (ICE).
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2. FEATURES
• Operating voltage range: 2.3V~5.5V.
• Operating temperature range: 0°C~70°C.
• Operating frequency rang (base on 2 clocks ):
* Crystal mode: DC~20MHz at 5V, DC~8MHz at 3V, DC~4MHz at 2.3V.
* RC mode: DC~4MHz at 5V, DC~4MHz at 3V, DC~4MHz at 2.3V.
• Low power consumption:
* Less then 3 mA at 5V/4MHz
EM78P451
OTP ROM
* Typically 10 µA during sleep mode
• Serial Peripheral Interface (SPI) available.
• 4K × 13 bits on chip ROM (EM78P451).
• 11 special function registers.
• 140× 8 bits on chip general-purposed registers.
• 5 bi-directional I/O ports (35 I/O pins).
• 3 LED direct sinking pins with internal serial resistors.
• Built-in RC oscillator with external serial resistor, ±10% variation.
• Built-in power-on reset.
• 5 stacks for subroutine nesting.
• 8-bit real time clock/counter (TCC) with overflow interrupt.
• Two machine clocks or four machine clocks per instruction cycle.
• Power down mode.
• Programmable wake up from sleep circuit on I/O ports.
• Programmable free running on-chip watchdog timer.
• 12 wake-up pins.
• 2 open-drain pins.
• 2 R-option pins.
• 32 programmable pull-high input pins.
• Packages:
* 40 pin DIP 600mil : EM78P451P.
* 44 pin QFP : EM78P451AQ.
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• Four types of interrupts.
* External interrupt (/INT).
* SPI transmission completed interrupt.
* TCC overflow interrupt.
* Timer1 comparator match interrupt.
EM78P451
OTP ROM
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3. PIN ASSIGNMENT
high by software.
high by software.
change wake up pin.
change wake up pin.
high by software, and
EM78P451
OTP ROM
VSS
INT
DATA
CLK
P90
P91
SDI/P92
SDO/P93
SCK/P94
SS/P95
P50
P51
P52
P53
P54
P55
P56
P57
P80
P81
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
OSCO
39
R-OSCI
38
VDD
37
P70
36
P71
35
P72
34
P67
33
P66
32
P65
31
P64
30
P63
29
P62
28
EM78P451P/WM
P61
27
P60
26
P87
25
P86
24
P85
23
P84
22
P83
21
P82
P90
P91
SDI/P92
SDO/P93
SCK/P94
SS/P95
P50
P51
P52
P53
P54
OSCO
R-OSCI
P81
NC
VDD
P82
NC
P83
NC
P84
NC
21
P85
P70
22
P86
33
32
31
30
29
28
27
26
25
24
23
DATA
CLK
INT
VSS
4443424140393837363534
1
2
3
4
5
6
7
8
9
10
11
EM78P451AQ
121314151617181920
P55
P80
P57
P56
Fig. 1 Pin Assignment
Table 1 Pin description
Symbol Pin No. Type Function Description
R-OSCI 39 I
* In XTAL mode: Crystal input; In internal C, external R mode: 56Kohm±5%
pull high for 1.8432MHz.
OSCO 40 O * In XTAL mode: Crystal output; In RC mode: Instruction clock output.
P90~P95 5~10 I/O
P80~P87 19~26 I/O
P70~P72 37~35 I/O
* General bi-directional I/O port. All of its pins can be pulled-
P90 and P91 are pin-change wake up pins.
* General bi-directional I/O port. All of its pins can be pulled-
P80 and P81 are also used as the R-option pins.
* LED direct-driving pin with internal serial resistor used as output and is
software defined.
* By connecting P74 and P76 together.
CLK 4 I/O
DATA 3 I/O
P60~P67 27~34 I/O
P50~P57 11~18 I/O
* P74 can be pulled-high by software and it is also a pin* P76 can be defined as an open-drain output.
* By connecting P75 and P77 together.
* P75 can be pulled-high by software and it is also a pin* P77 can be defined as an open-drain output.
* General bi-directional port. All of its pins can be pulled-
pin-change wake up pins.
* General bi-directional I/O port. All of its pins can be pulled-high individually
by software.
VDD 38 - * Power supply pin.
VSS 1 - * Ground pin.
/INT 2 I * An interrupt schmitt-triggered pin.
P71
P72
P67
P66
P65
P64
P63
P62
P61
P60
P87
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* The function of interrupt triggers at the falling edge.
up resistor is around 50K
* Users can enable it by software. The internal pull-
ohms.
SDI 7 I/O * Serial data in for SPI
SDO 8 I/O * Serial data out for SPI.
SCK 9 I/O * Serial clock for SPI.
/SS 10 I/O * /Slave select for SPI.
EM78P451
OTP ROM
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4. FUNCTION DESCRIPTION
EM78P451
OTP ROM
Oscillator/
Timming
Control
Sleep
&
Wake Up
Control
WDT
Time-out
P
P
5
5
0
1
IOC5
R5
P
P
5
5
2
3
P
5
4
Prescaler
R1(TCC)
P
P
P
5
5
5
5
6
7
/INT
Interrupt
Control
WDT Timer
ROM
Instruction
Register
P C
STACK 1
STACK 2
STACK 3
STACK 4
STACK 5
ALU
RAM
R4
IOC6
R6
P
P
P
P
P
P
P
6
0
P
6
6
6
6
6
6
6
1
2
3
4
5
6
7
P
7
0
IOC7
Instruction
Decoder
DATA & CONTROL BUS
R7
P
P
7
7
1
2
ACCR3
TMR1
IOC8
R8
P
P
P
P
P
P
P
8
0
P
8
8
8
8
8
8
8
1
2
3
4
5
6
7
IOC9
R9
P
P
P
P
9
0
P
P
9
9
9
5
9
4
3
2
5
1
/
/
/
/
S
S
S
/
D
C
D
S
K
O
I
S
SPI
ENGIN
Fig. 2 Functional Block Diagram
4.1 Operational Registers
1. R0 (Indirect Address Register)
R0 is not a physically implemented register. It is used as an indirect addressing pointer. Any
instruction using R0 as register actually accesses data pointed by the RAM Select Register (R4).
2. R1 (TCC)
• Increased by the instruction cycle clock.
• Written and read by program as any other register.
3. R2 (Program Counter) & Stack
• R2 and the hardware stacks are 12 bits wide.
• The structure is depicted in Fig. 3.
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EM78P451
OTP ROM
• Generates 4K × 13 on-chip ROM addresses to the relative programming instruction codes. One
program page is 1024 words long.
• All the R2 bits are set to "1"s as a RESET condition occurs.
• "JMP" instruction allows direct loading of the lower 10 program counter bits. Thus, "JMP" allows
jump to any location on one page.
• "CALL" instruction loads the lower 10 bits of the PC, and then PC+1 is pushed into the stack. Thus,
the subroutine entry address can be located anywhere within a page
• "RET" ("RETL k", "RETI") instruction loads the program counter with the contents at the top of stack.
• "MOV R2, A" allows the loading of an address from the "A" register to the lower 8 bits of PC, and the
ninth and tenth bits (A8~A9) of PC are cleared.
• "ADD R2, A" allows a relative address be added to the current PC, and the ninth and tenth bits of PC
are cleared.
• Any instruction that is written to R2 (e.g. "ADD R2, A", "MOV R2, A", "BC R2,6",⋅⋅⋅⋅⋅) (except "TBL")
will cause the ninth and tenth bits (A8~A9) of PC to be cleared. Thus, the computed jump is limited
to the first 256 locations of any program page.
• "TBL" allows a relative address be added to the current PC (R2+A→R2), and contents of the ninth
and tenth bits (A8~A9) of PC are not changed. Thus, the computed jump can be on the second (or
third, 4th) 256 locations on one program page.
• In case of EM78P451, the most significant bits (A10~A11) will be loaded with the contents of bits
PS0~PS1 in the status register (R3) upon the execution of a "JMP", "CALL", or any other
instructions which writes to R2.
• All instructions are single instruction cycle (fclk/2 or fclk/4) except for the instruction that would
change the contents R2. Such instruction will need one more instruction cycle.
PC
A11A10 A9A8 A7 ~ A0
BFF
C00
FFF
000
3FF
400
7FF
800
Page 0
Page 1
Page 2
Page 3
00
01
10
11
CALL
RET
RETL
RETI
001:Hareware interrupt location
002:Software interrupt (INT instruction) location
FFF:Reset location
Stack 1
Stack 2
Stack 3
Stack 4
Stack 5
Fig. 3 Program Counter Organization
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EM78P451
OTP ROM
4. R3 (Status Register)
7 6 5 4 3 2 1 0
GP PS1 PS0 T P Z DC C
• Bit 0 (C) Carry flag
• Bit 1 (DC) Auxiliary carry flag
• Bit 2 (Z) Zero flag. Set to "1" if the result of an arithmetic or logic operation is zero.
• Bit 3 (P) Power down bit. Set to 1 during power on or by a "WDTC" command and reset to 0 by a
"SLEP" command.
• Bit 4 (T) Time-out bit. Set to 1 with the "SLEP" and the "WDTC" commands, or during power up and
reset to 0 with WDT timeout.
• Bits 5 (PS0) ~ 6 (PS1) Page select bits. PS0~PS1 are used to pre-select a program memory page.
When executing a "JMP", "CALL", or other instructions which causes the program counter to be
changed (e.g. MOV R2, A), PS0~PS1 are loaded into the 11th and 12th bits of the program counter
where it selects selecting one of the available program memory pages. Note that RET (RETL, RETI)
instruction does not change the PS0~PS1 bits. That is, the return will always be to the page from
where the subroutine was called, regardless of the current setting of PS0~PS1 bits. PS1 bit is not
used (read as "0") and cannot be modified in EM78P451.
PS1 PS0 Program memory page [Address]
0 0 Page 0 [000-3FF]
0 1 Page 1 [400-7FF]
1 0 Page 2 [800-BFF]
1 1 Page 3 [C00-FFF]
• Bit 7 (GP) General read/write bit.
5. R4 (RAM Select Register)
• Bits 0~5 are used to select the registers (address: 00~3F) in the indirect addressing mode.
• Bits 6~7 determine which bank is activated among the 4 banks.
• If no indirect addressing is used, the RSR is used as an 8-bit general-purposed read/writer register.
• See the configuration of the data memory in Fig. 4.
6. R5~R8 (Port 5 ~ Port8)
• Four general 8 bits I/O registers
• Both P74 and P76 read or write data from the DATA pin, while both P75 and P77 read or write data
from the CLK pin.
7. R9 (Port9)
• A general 6-bit I/O register. The values of the two most significant bits are read as "0".
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EM78P451
OTP ROM
00
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
11
1E
1F
R0
R1 (TCC)
R2 (PC)
R3 (Status)
R4 (RSR)
R5 (Port 5)
R6 (Port 6)
R7 (Port 7)
R8 (Port 8)
R9 (Port 9)
RA
RB
RC
RD
RE
RF
16x8
Common
Register
STACK 0
STACK 1
STACK 2
STACK 3
STACK 4
IOC5
IOC6
IOC7
IOC8
IOC9
IOCC
IOCD
IOCE
IOCF
00 01 10 11
20
21
3E
3F R3F
31x8
Bank
Register
(Bank 0)
31x8
Bank
Register
(Bank 1)
31x8
Bank
Register
(Bank 2)
31x8
Bank
Register
(Bank 3)
Fig. 4 Data memory configuration
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EM78P451
OTP ROM
8. RA (SPIRB: SPI Read Buffer)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
0X0A SPIRB/RA SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1
• SRB7~SRB0 are the 8-bit data when complete transmission by SPI.
9. RB (SPIWB: SPI Write Buffer)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0B SPIWB/RB SWB7 SWB6 SWB5 SWB4 SWB3 SWB2 SWB1 SWB0
• SWB7~SWB0 are the 8-bit data that are waiting for transmission by SPI.
10. RC (SPIS: SPI Status Segister)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0C SPIS/RC -- -- -- TM1IF OD3 OD4 RBFIF RBF
• TM1IF (bit 4):
1 = In timer1 mode, receiving completed, and an interrupt occurs if enabled.
0 = In timer1 mode, receiving not completed yet, and an interrupt does not occur.
• OD3 (bit 3): Open-Drain Control bit
1 = Open-drain enable for SDO,
0 = Open-drain disable for SDO.
• OD4 (bit 2): Open-Drain Control bit
1 = Open-drain enable for SCK,
0 = Open-drain disable for SCK.
• RBFIF (bit 1):Read Buffer Full Interrupt Flag
1 = Receiving completed, SPIRB is fully exchanged, and an interrupt occurs if enabled.
0 = Receiving not completed yet; and SPIRB has not fully exchanged.
• RBF (bit 0): Read Buffer Full flag
1 = Receiving completed; SPIRB is fully exchanged.
0 = Receiving not completed yet, and SPIRB has not fully exchanged.
11. RD (SPIC: SPI Control Register)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0D SPIC/RD CES SPIE SRO SSE - SBRS2 SBRS1 SBRS0
• CES (bit 7): Clock Edge Select bit
1 = Data shifts out on falling edge, and shifts in on rising edge. Data is on hold during the high level.
0 = Data shifts out on rising edge, and shifts in on falling edge. Data is on hold during the low level.
• SPIE (bit 6): SPI Enable bit
1= Enable SPI mode
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EM78P451
OTP ROM
0= Disable SPI mode
• SRO (bit 5): SPI Read Overflow bit
1 = A new data is received while the previous data is still being held in the SPIB register. In this
situation, the data in SPIS register will be destroyed. To avoid setting this bit, users had better read
SPIRB register even if only the transmission is implemented.
0 = No overflow.
<Note>: This can only occur in slave mode.
• SSE (bit 4): SPI Shift Enable bit
1 = Start to shift, and keep on 1 while the current byte is still being transmitted.
0 = Reset as soon as the shifting is complete, and the next byte is ready to shift.
<Note>: This bit will reset to 0 at every one-byte transmission by the hardware
• SBRS (bit 2~bit 0): SPI Baud Rate Select bits
SPI baud rate table is illustrated in SPI section in later pages.
12. RE (TMR1: Timer1 register)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0X0E TMR1/RE TMR17 TMR16 TMR15 TMR14 TMR13 TMR12 TMR11 TMR10
• TMR17~TMR10 is bit set of timer1 register and it increases until the value matches PWP and then,
it resets to 0.
13. RF (PWP: Pulse width preset register)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0F PWP/RF PWP7 PWP6 PWP5 PWP4 PWP3 PWP2 PWP1 PWP0
• PWP7~PWP0 is bit set of pulse width preset in advance for the desired width of baud clock.
14. R20~R3E (General Purpose Register)
• RA~R1F, and R20~R3E (including Banks 0~3) are general-purpose registers.
15. R3F (Interrupt Status Register)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x3F ISR/R3F - - - - TM1IF SPIIF EXIF TCIF
• Bit 0 (TCIF) the flag of the TCC overflow interrupt. Set as TCC overflow; flag cleared by software.
• Bit 1 (EXIF) External interrupt flag. Set by falling edge on /INT pin, flag cleared by software
• Bit 2 (SPIIF) SPI interrupt flag. Set by data transmission complete, flag cleared by software.
• Bit 3 (TM1IF) Timer1 interrupt flag. Set by the comparator at Timer1 application, flag cleared by
software.
• Bits 2~7 are not used and read as “0”.
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• "1" means interrupt request, "0" means non-interrupt.
• R3F can be cleared by instruction, but cannot be set by instruction.
• IOCF is the interrupt mask register.
• Note that to read R3F will result to "logic AND" of R3F and IOCF.
4.2 Special Purpose Registers
1. A (Accumulator)
• Internal data transfer, or instruction operand holding.
• A non-addressable register.
2. CONT (Control Register)
7 6 5 4 3 2 1 0
/PHEN /INT - - PAB PSR2 PSR1 PSR0
EM78P451
OTP ROM
• Bit 7 (/PHEN) I/O pin pull-high enable flag.
0: For P60~P67, P74~P75 and P90~P95, the pull-high function is enabled.
1: The pull-high function is disabled.
• Bit 6 (INT) An interrupt enable flag cannot be written by the CONTW instruction.
0: interrupt masked by the DISI instruction.
1: interrupt enabled by the ENI or RETI instruction.
• Bit4, 5 Not used, and to be read as “0”.
• Bit 3 (PAB) Prescaler assignment bit.
0: TCC
1: WDT
• Bit 0 (PSR0) ~ Bit 2 (PSR2) TCC/WDT prescaler bits.
PSR2 PSR1 PSR0 TCC Rate WDT Rate
0 0 0 1:2 1:1
0 0 1 1:4 1:2
0 1 0 1:8 1:4
0 1 1 1:16 1:8
1 0 0 1:32 1:16
1 0 1 1:64 1:32
1 1 0 1:128 1:64
1 1 1 1:256 1:128
• Bits 0~3, and 7 of the CONT register are readable and writable.
3. IOC5 ~ IOC9 (I/O Port Control Register)
• "1" put the relative I/O pin into high impedance, while "0" put the relative I/O pin as output.
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EM78P451
OTP ROM
• Both P74 and P76 should not be defined as output pins at the same time. This also applies to both
P75 and P77.
• Only the lower 6 bits of the IOC9 register are used.
4. IOCC (T1CON: Timer1 control register)
Address
0x0C T1CON/IOCC 0 0 0 0 0 TM1E TM1P1 TM1P0
• TM1E (bit2): Timer1 Function Enable bit
1 = Enable timer1 function.
0 = Disable timer1 function as default.
• TM1P (bit1~bit0): Timer1 Prescaler bit
Timer1 prescaler table for FOSC will be illustrated in the Section on Timer1 in later pages.
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
5. IOCD (Pull-high Control Register)
7 6 5 4 3 2 1 0
S7 - - - /PU9 /PU8 /PU6 /PU5
• The default values of /PU5, /PU6, /PU8, and /PU9 are one, which means the pull-high function is
disabled.
• /PU6 and /PU9 are “AND” gating with /PHEN, that is, when each one is written as “0” pull high is
enabled.
• S7 defines the driving ability of the P70-P72.
0: Normal output.
1: Enhance the driving ability of LED.
6. IOCE (WDT Control Register)
7 6 5 4 3 2 1 0
- ODE WDTE SLPC ROC - - /WUE
• Bit 0 (/WUE) Control bit used to enable the wake-up function of P60~P67, P74~P75, and P90~P91.
0: Enable the wake-up function.
1: Disable the wake-up function.
The /WUE bit can be read and written.
• Bit 3 (ROC) ROC is used for the R-option. Setting ROC to "1" will enable the status of R-option pins
(P80, P81) to be read by the controller. Clearing ROC will disable the R-option function. Otherwise,
the R-option function is introduced. Users must connect the P81 pin or/and P80 pin to VSS by a
560KΩ external resistor (Rex). If Rex is connected/disconnected with VDD, the status of P80 (P81)
will be read as "0"/"1" (refer to Fig. 7(b)). The ROC bit can be read and written.
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EM78P451
OTP ROM
• Bit 4 (SLPC) This bit is set by hardware at the falling edge of wake-up signal and is cleared in
software. SLPC is used to control the oscillator operation. The oscillator is disabled (oscillator is
stopped, and the controller enters the SLEEP2 mode) on the high-to-low transition and is enabled
(the controller is awakened from SLEEP2 mode) on low-to-high transition. In order to ensure the
stable output of the oscillator, once the oscillator is enabled again, there is a delay for approximately
18 ms (oscillator start-up timer (OST)) before the next program instruction is executed. The OST is
always activated by wake-up from sleep mode whether the Code Option bit ENWDT is "0" or not.
After waking up, the WDT is enabled if Code Option ENWDT is "1". The block diagram of SLEEP2
mode and wake-up caused by input triggered is depicted in Fig. 5. The SLPC bit can be read and
written.
• Bit 5 (WDTE) Control bit used to enable Watchdog timer.
The WDTE bit can be used only if ENWDT, the CODE Option bit, is "1". If the ENWDT bit is "1", then
WDT can be disabled/enabled by the WDTE bit.
0: Disable WDT.
1: Enable WDT.
The WDTE bit is not used if ENWDT, the CODE Option bit ENWDT, is "0". That is, if the ENWDT bit
is "0", WDT is always disabled no matter what the WDTE bit is.
The WDTE bit can be read and written.
• Bit 6 (ODE) Open-drain control bit.
0: Both P76 and P77 are normally I/O pins.
1: Both P76 and P77 pins have the open-drain function inside.
The ODE bit can be read and written.
• Bits 1~2, and 7 Not used.
7. IOCF (Interrupt Mask Register)
7 6 5 4 3 2 1 0
- - - - TM1IE SPIIE EXIE TCIE
• Bit 0 (TCIE) TCIF interrupt enable bit.
0: disable TCIF interrupt
1: enable TCIF interrupt
• Bit 1 (EXIE) EXIF interrupt enable bit.
0: disable EXIF interrupt
1: enable EXIF interrupt
• Bit 2 (SPIIE) SPI interrupt enable bit.
0: disable SPI interrupt
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1: enable SPI interrupt
P
R
C
• Bit 3 (TM1IE) TM1IE interrupt enable bit.
0: disable TM1IE interrupt
1: enable TM1IE interrupt
• Bits 4~7 Not used.
• Individual interrupt is enabled by setting its associated control bit in IOCF to "1".
• The IOCF Register could be read and written.
EM78P451
OTP ROM
Oscillator
Enable Disable
Q D
CLK
Q
L
Clear
from S/W
Set
Reset
/WUE
/WUE
VCC
8
/WUE
P60~P67
VCC
/WUE
/PHEN
4
P74~P75, P90~P91
Fig. 5 Block Diagram of Sleep Mode and Wake-up Circuits on I/O Ports
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EM78P451
OTP ROM
4.3 TCC/WDT Presacler
An 8-bit counter is available as prescaler for the TCC or WDT. The prescaler is available for either the
TCC or WDT only at any given time, and the PAB bit of CONT register is used to determine the
prescaler assignment. The PSR0~PSR2 bits determine the prescale ratio. The prescaler is cleared
each time the instruction is written to TCC under TCC mode. The WDT and prescaler, when assigned to
WDT mode, are cleared by the WDTC or SLEP instructions. Fig. 6 depicts the circuit diagram of
TCC/WDT.
• R1(TCC) is an 8-bit timer/counter. TCC will increase by one at every instruction cycle (without
prescaler).
• The watchdog timer is a free running on-chip RC oscillator. The WDT will keep running even when the
oscillator driver has been turned off (i.e. in sleep mode). During normal operation or sleep mode, a
WDT time-out (if enabled) will cause the device to reset. The WDT can be enabled or disabled any
time during the normal mode by software programming (if Code Option bit ENWDT is "1"). Refer to
WDTE bit of IOCE register. Without presacler, the WDT time-out period is approximately 18 ms1.
4.4 I/O Ports
The I/O registers, from Port 5 to Port 9, are bi-directional tri-state I/O ports. P60~P67, P74~P75, and
P90~P91 provide internal pull-high. P60~P67, P74~P75, and P90~P95 provide programmable
wake-up function through software. P76~P77 can have open-drain output by software control. P80~P81
are the R-option pins which are enabled by software. When the R-option function is used, it is
recommended that P80 and P81 are used as output pins. During R-option enabled state, P80 and P81
must be programmed as input pins. If an external resistor is connected to P80 (P81) for the R-option
function, the current consumption should be taken as an important factor in the applications for low
power consideration.
The I/O ports can be defined as "input" or "output" pins by the I/O control registers (IOC5~IOC9) under
program control. The I/O registers and I/O control registers are both readable and writable. The I/O
interface circuit is shown in Fig. 7. Note that the reading path source of input and output pins is different
when reading the I/O port.
1
NOTE: Vdd = 5V, set up time period = 16.2ms ± 5%
Vdd = 3V, set up time period = 18.0ms ± 5%
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EM78P451
OTP ROM
CLK(=Fosc/2)
WDT
WDTE
(in IOCE)
Data Bus
1
M
U
X
0
PAB
0
M
U
X
1
8- bit Counter
SYNC
2 cycles
TCC(R1)
TCC overflow interrupt
PSR0~PSR2
8 - to - 1 MUX
0 1
MUX
WDT timeout
PAB
Fig. 6 Block Diagram of TCC WDT
PCRD
P
PORT
Q
Q
0
M
U
1
X
D
R
CLK
C
Q
L
P
R
CLK
C
Q
L
PCWR
IOD
D
PDWR
PDRD
Fig. 7 (a) The Circuit of I/O Port and I/O Control Register
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PCRD
EM78P451
OTP ROM
Weakly
Pull-up
PORT
VCC
Rex*
ROC
P
Q
D
R
CLK
C
Q
L
P
Q
R
CLK
C
Q
L
0
M
U
1
X
*The Rex is 560K ohm external resistor
PCWR
D
PDWR
PDRD
Fig.7(b) The Circuit of I/O Port with R-option (P80, P81)
IOD
4.5 SERIAL PERIPHERAL INTERFACE MODE
1. Overview & Features
Overview:
Figures 8, 9, and 10 show how EM78P451 communicates with other devices through SPI module.
If EM78P451 is a master controller, it sends clock through the SCK pin. A couple of 8-bit data are
transmitted and received at the same time. However, if EM78P451is defined as a slave, its SCK
pin could be programmed as an input pin. Data will continue to be shifted based on both the clock
rate and the selected edge.
Features:
• Operation in either Master mode or Slave mode,
• Three-wire or four-wire synchronous communication; that is, full duplex
• Programmable baud rates of communication,
• Programming clock polarity, (RD bit7)
• Interrupt flag available for the read buffer full,
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• Up to 8 MHz ( maximum ) bit frequency,
SDO
SPIW
SPIR Reg
SPIR Reg
SPIW Reg
Reg
/SS
EM78P451
OTP ROM
SPIS Reg
SPIS Reg
Bit 7
Master Device
Master
SDI
SCK
SPI Module
SPI Module
Slave Device
Fig. 8 SPI Master/Slave Communication
SDI
SDO
SCK
/SS
Vdd
P50
P51
P52
P53
SCK
SDI
/SS
Slave Device 1
SDO
SCK
SDI
/SS
Slave Device 2
SDO
SCK
SDI
/SS
Slave Device 3
SDO
Slave Device 4
/SS
SCK
SDI
SDO
Fig. 9 The SPI Configuration of Single-Master and Multi-Slave
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EM78P451
OTP ROM
Master1 Master2
or
Slave1
SDO
SCK
SDI
/SS
Slave 2 for master 1
SDI
SDO
SCK
/SS
P50
P51
P52
P53
/SS
SCK
SDI
SDO
/SS
SCK
SDI
SDI
SDO
SCK
/SS
P50
P51
P52
P53
SDO
or
Slave6
Slave 3 for Master 1/2 Slave 4 for Master1/2 Slave 5 for Master 2
Fig. 10 The SPI Configuration of Single-Master and Multi-Slave
/SS
SCK
SDI
SDO
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2. SPI Function Description
Read Write
EM78P451
OTP ROM
RBF RBFI
Buffer Full Detector
P92/SDI
P93/SDO
P95/ /SS
Tsco
SPI Mode Select
Register
Set to 1
8-1 MUX
SBR0 ~SBR2
/SS
Prescaler
4, 8, 16, 32, 64
TMR1/2
SPIR reg
SPIS reg
bit 0
SBR2~SBR0
8
Fig. 11 SPI Block Diagram
SPI Write Register
(0X0B)
Clock Select
2
SDO
SE
Edge
Select
SPIW
shift right
SPIC bit6
Edge
Select
SPI
/SS
Shift Clock
SPI Shift Buffer
reg
bit 7
SPIC reg
Noise
Filter
SDI
P94/SCK
SPI Read Register
(0X0A)
FOSC
2 1 0
SPIC
SPIWB
7~0
T1CON
1 0
6 4
7 2
SPIC
1 0 4
SPIS
INTC
SPIC
7~0
SPIRB
DATA BUS
Fig. 12 The Function Block Diagram of SPI Transmission
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EM78P451
OTP ROM
The following describes the function of each block and explains how to carry out the SPI
communication with the signals depicted in Fig.11 and Fig.12:
• P92/SDI: Serial Data In.
• P93/SDO: Serial Data Out.
• P94/SCK: Serial Clock.
• P95//SS: /Slave Select (Option). This pin (/SS) may be required during a slave mode.
• RBF: Set by Buffer Full Detector, and reset in software.
• RBIF: Set by Buffer Full Detector, and reset in software.
• Buffer Full Detector: Sets to 1 when an 8-bit shifting is completed.
• SSE: Loads the data in SPIS register, and begin to shift
• SPIS reg.: Shifting byte in and out. The MSB is shifted first. Both the SPIS register and the SPIW
register are loaded at the same time. Once data are written, SPIS starts transmission / reception.
The received data will be moved to the SPIR register as the shifting of the 8-bit data is completed.
The RBF (Read Buffer Full) flag and the RBFI(Read Buffer Full Interrupt) flag are then set.
• SPIR reg.: Read buffer. The buffer will be updated as the 8-bit shifting is completed. The data must
be read before the next reception is completed. The RBF flag is cleared as the SPIR register reads.
• SPIW reg.: Write buffer. The buffer will deny any attempt to write until the 8-bit shifting is
completed.
The SSE bit will be kept in 1 if the communication is still undergoing. This flag must be cleared as the
shifting is completed. Users can determine if the next write attempt is available.
• SBRS2~SBRS0: Programming the clock frequency/rates and sources.
• Clock Select: Selecting either the internal or external clock as the shifting clock.
• Edge Select: Selecting the appropriate clock edges by programming the CES bit
3. SPI Signal & Pin Description
The detailed functions of the four pins, SDI, SDO, SCK, and /SS, which are shown in Fig. 9, are as
follows:
SDI/P92 (Pin 7):
• Serial Data In,
• Receive serially, the Most Significant Bit (MSB) first, Least Significant Bit (LSB) last,
• Defined as high-impedance, if not selected,
• Program the same clock rate and clock edge to latch on both the master and slave devices,
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OTP ROM
• The received byte will update the transmitted byte,
• Both the RBF and RBFIF bits (located in Register 0x0C) will be set as the SPI operation is
completed.
• Timing is shown in Fig.13 and14.
SDO/P93 (Pin 8):
• Serial Data Out,
• Transmit serially; the Most Significant Bit (MSB) first, Least Significant Bit (LSB) last,
• Program the same clock rate and clock edge to latch on both the master and slave devices,
• The received byte will update the transmitted byte,
• The CES (located in Register 0x0D) bit will be reset, as the SPI operation is completed.
• Timing is shown in Fig.13 and 14.
SCK/P94 (Pin 9):
• Serial Clock
• Generated by a master device
• Synchronize the data communication on both the SDI and SDO pins
• The CES (located in Register 0x0D) is used to select the edge to communicate.
• The SBR0~SBR2 (located in Register 0x0D) is used to determine the baud rate of
communication
• The CES, SBR0, SBR1, and SBR2 bits have no effect in the slave mode
• Timing is show in Fig.13 and 14
/SS/P95 (Pin 10):
• Slave Select; negative logic,
• Generated by a master device to signify the slave(s) to receive data,
• Goes low before the first cycle of SCK appears, and remains low until the last (eighth) cycle is
completed,
• Ignores the data on the SDI and SDO pins while /SS is high, because the SDO is no longer
driven.
• Timing is shown in Fig.13 and Fig. 14.
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EM78P451
OTP ROM
4. Programmed the related registers
As the SPI mode is defined, the related registers of this operation are shown in Table 2 and Table 3.
Table 2 Related Control Registers of the SPI Mode
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0D *SPIC/RD CES SPIE SRO SSE -- SBR2 SBR1 SBR0
0x0F INTC/IOCF -- -- -- -- TM1IE SPIIE EXIE TCIE
• SPIC: SPI Control Register.
• CES (bit 7): Clock Edge Select bit
1 = Data shifts out on falling edge, and shifts in on rising edge. Data is on hold during the high level.
0 = Data shifts out on rising edge, and shifts in on falling edge. Data is on hold during the low level.
• SPIE (bit 6):SPI Enable bit
1 = Enable SPI mode
0 = Disable SPI mode
• SRO (bit 5):SPI Read Overflow bit
1 = A new data is received while the previous data is still being on hold in the SPIB register. Under
this condition, the data in SPIS register will be destroyed. To avoid setting this bit, users should read
the SPIRB register even if the transmission is implemented only.
0 = No overflow.
<Note>:This can only occur under slave mode.
• SSE (bit 4):SPI Shift Enable bit
1 = Start to shift, and stays on 1 while the current byte continues to transmit.
0 = Reset as soon as the shifting is completed and the next byte is ready to shift.
<Note>: This bit can be reset by hardware only.
• SBRS (bit 2~0): SPI Baud Rate Select Bits
SBRS2 (Bit 2) SBRS1 (Bit 1) SBRS0 (Bit 0) Mode Baud Rate
0 0 0 Master Fsco/2
0 0 1 Master Fsco/4
0 1 0 Master Fsco/8
0 1 1 Master Fsco/16
1 0 0 Master Fsco/32
1 0 1 Slave /SS enable
1 1 0 Slave /SS disable
1 1 1 Master TMR1/2
<Note> In master mode, /SS is disable.
• INTC: Interrupt control register
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• Bit 3 (TM1IE) TM1IE interrupt enable bit.
0: disable TM1IE interrupt
1: enable TM1IE interrupt
• Bit 2 (SPIIE) SPI interrupt enable bit.
0: disable SPI interrupt
1: enable SPI interrupt
• Bit 1 (EXIE) EXIF interrupt enable bit.
0: disable EXIF interrupt
1: enable EXIF interrupt
• Bit 0 (TCIE) TCIF interrupt enable bit.
0: disable TCIF interrupt
EM78P451
OTP ROM
1: enable TCIF interrupt
Table 3 Related Status/Data Registers of the SPI Mode
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0X0A SPIRB/RA SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 SRB0
0x0B SPIWB/RB SWB7 SWB6 SWB5 SWB4 SWB3 SWB2 SWB1 SWB0
0x0C SPIS/RC 0 0 0 TM1IF OD3 OD4 RBFIF RBF
• SPIRB: SPI Read Buffer. Once the serial data is received completely, it will load to SPIRB from
SPISR. The RBF bit and the RBFIF bit in the SPIS register will be set also.
• SPIWB: SPI Write Buffer. As a transmitted data is loaded, the SPIS register stands by and start to
shift the data when sensing SCK edge with SSE set to “1”.
• SPIS: SPI Status register
• TM1IF (bit 4):Timer1 interrupt flag.
• OD3 (bit 3):Open-Drain Control bit (P93)
1 = Open-drain enable for SDO,
0 = Open-drain disable for SDO.
• OD4 (bit 2):Open Drain-Control bit (P94)
1 = Open-drain enable for SCK,
0 = Open-drain disable for SCK.
• RBFIF (bit 1):Read Buffer Full Interrupt flag
1 = Receive is completed, SPIB is full, and an interrupt occurs if enabled.
0 = Receive is ongoing, SPIB is empty.
• RBF (bit 0):Read Buffer Full flag
1 = Receive is completed, SPIB is full.
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EM78P451
OTP ROM
0 = Receive is ongoingt, SPIB is empty.
5. SPI Mode Timing
The edge of SCK is selected by programming bit CES. The waveform shown in Fig.13 is applicable
regardless of whether the EM78P451 is under master or slave mode with /SS disabled. However, The
waveform in Fig. 14 can only be implemented in slave mode with /SS enabled.
Fig. 13 SPI Mode with /SS Disable
Fig. 14 SPI Mode with /SS Enable
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6. Software Application of SPI
Example for SPI:
For Master
ORG 0X0
SETTING:
CLRA
IOW 0X05 ;SET PORT5 OUTPUT
IOW 0X06 ;SET PORT6 OUTPUT
MOV 0X05,A
MOV A,@0B11001111 ;SET PRESCALER FOR WDT
CONTW
EM78P451
OTP ROM
MOV A,@0B00010001 ;DISABLE WAKEUP FUNCTION
IOW 0X0E
MOV A,@0B00000000 ;DISABLE INTERRUPT
IOW 0X0F
MOV A,@0X07 ;SDI INPUT AND SDO, SCK OUTPUT
IOW 0X09
MOV A,@0B10000000 ;CLEAR RBF AND RBFIF FLAG
MOV 0X0C,A
MOV A,@0B11100000 ;SELECT CLOCK EDGE AND ENABLE SPI
MOV 0X0D,A
START:
WDTC
BC 0X0C,1 ;CLEAR RBFIF FLAG
MOV A,@0XFF
MOV 0X05,A ;SHOW A SIGNAL AT PORT5
MOV 0X0A,A ;MOVE FF AT READ BUFFER
MOV A,@0XAA ;MOVE AA AT WRITE BUFFER
MOV 0X0B,A
BS 0X0D,4 ;START TO SHIFT SPI DATA
NOP
JBC 0X0D,4 ;POLLING LOOP FOR CHECKING SPI TRANSMISSION COMPLETED
JMP $-2
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EM78P451
OTP ROM
BC 0X03,2
CALL DELAY ;TO CATCH THE DATA FROM SLAVER
MOV A,0X0A
XOR A,@0X5A ;COMPARE THE DATA FROM SLAVER
JBS 0X03,2
JMP START
FLAG:
MOV A,@0X55 ;SHOW THE SIGNAL WHEN RECEIVING CORRECT DATA FROM SLAVER
MOV 0X05,A
CALL DELAY
JMP START
DELAY:
; (USER’S PROGRAM)
EOP
ORG 0XFFF
JMP SETTING
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EM78P451
OTP ROM
For Slaver
ORG 0X0
INITI:
JMP INIT
ORG 0X2
INTERRUPT: ;INTERRUPT ADDRESS
MOV A,@0X55
MOV 0X06,A ;SHOW A SIGNAL AT PORT 6 WHEN ENTERING INTERRUPT
MOV A,@0B11100110 ;ENABLE SPI, /SS DISABLED
MOV 0X0D,A
BS 0X0D,4 ;KEEP SSE AT 1 TO WAIT FOR SCK SIGNAL IN ORDER TO SHIFT DATA
MOV A,@0X00 ;MOVE 00 TO WRITE BUFFER IN ORDER TO KEEP MASTER’S READ BUFFER AS 00
MOV 0X0B,A
BS 0X0D,4 ;KEEP SSE AT 1 TO WAIT FOR SCK SIGNAL IN ORDER TO SHIFT DATA
NOP
JBC 0X0D,4 ;POLLING LOOP FOR CHECKING SPI TRANSMISSION COMPLETED
JMP $-2
BS 0X0D,4 ;KEEP SSE AT 1 TO WAIT FOR SCK SIGNAL IN ORDER TO SHIFT DATA
BC 0X03,2
MOV A,0X0A
MOV 0X06,A ;READ MASTER’S DATA FROM READ BUFFER
XOR A,@0XAA ;CHECK PASS SIGNAL FROM READ BUFFER
JBS 0X03,2
JMP $-6
JMP SPI
ORG 0X30
INIT:
CLRA
IOW 0X05
IOW 0X06
MOV 0X05,A
MOV 0X06,A
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MOV A,@0XFF
IOW 0X08
MOV A,@0B11001111 ;SET PRESCALER FOR WDT
CONTW
MOV A,@0B00010001 ;DISABLE WAKEUP FUNCTION
IOW 0X0E
MOV A,@0B00000010 ;ENABLE EXTERNAL INTERRUPT
IOW 0XF
ENI
MOV A,@0B00110111
IOW 0X09
EM78P451
OTP ROM
BC 0X3F,1 ;CLEAR RBFIF FLAG
NOP
JBS 0X3F,1 ;POLLING LOOP FOR CHECKING INTERRUPT OCCURENCE
JMP $-2
JMP INTERRUPT
SPI:
BS 0X0D,4 ;KEEP SSE ENABLED AS LONG AS POSSIBLE
WDTC
MOV A,@0X0F ;SHOW A SIGNAL WHEN ENTERING SPI LOOP
MOV 0X06,A
JBC 0X08,1 ;CHOOSE P81 AS A SIGNAL BUTTON
JMP SPI
MOV A,@0X5A ;MOVE 5A INTO WRITE BUFFER WHEN P81 BUTTON IS PUSHED
MOV 0X0B,A
NOP
JBC 0X0D,4 ;POLLING LOOP FOR CHECKING SPI TRANSMISSION COMPLETED
JMP $-2
BS 0XD,4
NOP
NOP
MOV A,@0XF0 ;DISPLAY AT PORT6 WHEN P81 BUTTON IS PUSHED
MOV 0X06,A
MOV A,@0X00 ;SEND A SIGNAL TO MASTER TO PREVENT INFINITE LOOP
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MOV 0X0B,A
NOP
JBC 0X0D,4
JMP $-2
BS 0X0D,4
BS 0X0C,7
BC 0X0C,1
NOP
JMP SPI
DELAY:
; (USER’S PROGRAM)
EM78P451
OTP ROM
EOP
ORG 0XFFF
JMP INITI
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4.6 Timer 1
1. Overview
Timer1(TMR1) is an eight-bit clock counter with a programmable prescaler. It is designed for the SPI
module as a baud rate clock generator. TMR1 can be read and written and cleared on any reset
conditions. If employed, it can be turned down for power saving by setting TMR1EN bit [T1CON<2>]
to 0.
2. Function description
Fig. 15 shows TIMER1 block diagram. Each signal and block is described as follows:
EM78P451
OTP ROM
Fig. 15 TIMER1 Block Diagram
• OSC/4: Input clock.
• Prescaler: Option of 1:1, 1:4, 1:8, and 1:16 defined by T1P1 and T1P02 (T1CON<1, 0>). It is
cleared when a value is written to TMR1 or T1CON, and during any kind of reset as well.
• PWP: Pulse width preset register. The desired width of baud clock is written in advance.
• TMR1: Timer 1 register. TMR1 increases until it matches with PWP, and then resets to 0. If it is
chosen optionally in the SPI mode, its output is fed as a shifting clock.
• Comparator: To change the output status while a match occurs. The TMR1IF flag will be set at the
same time.
3. Programmed the related registers
The related registers of the defining TMR1 operation are shown in Table 4 and Table 5
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EM78P451
OTP ROM
Table 4 Related Control Registers of the TMR1
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0C SPIS/RC 0 0 0 TM1IF OD3 OD4 RBFIF RBF
0x0F INTC/IOCF 0 0 0 0 TM1IE SPIIE EXIE TCIE
Table 5 Related Status/Data Registers ofTMR1
Address
0X0E TMR1/RE TMR17 TMR16 TMR15 TMR14 TMR13 TMR12 TMR11 TMR10
0x0F PWP/RF PWP7 PWP6 PWP5 PWP4 PWP3 PWP2 PWP1 PWP0
0x0C T1CON/IOCC
• TMR1: Timer1 Register
• PWP: Pulse Width Preset Register
• T1CON: Timer1 Control Register
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 TM1E TM1P1 TM1P0
TMR17~TMR10 is bit set of Timer1 register and it increases until the value matches PWP and then
it reset to 0.
PWP7~PWP0 is bit set of pulse width preset for the desired width of baud clock in advance.
TM1E (bit2): Timer1 enable bit
TM1P1 and TM1P0 (bit1~0): Timer1 prescaler for FSCO
TM1P1 TM1P0 Prescaler Rate
0 0 1:1
0 1 1:4
1 0 1:8
1 1 1:16
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4.7 RESET and Wake-up
A RESET is initiated by
(1) Power on reset, or
(2) WDT timeout. (if enabled)
Oscillator
Power-
on Reset
Voltage
Detector
VDD
D Q
CLK
CLR
EM78P451
OTP ROM
CLK
WDTE
WDT
WDT timeout
Setup
Time
Reset
Fig. 16 Block Diagram of Reset
The device is kept in a RESET condition for a period of approx. 18ms1 (one oscillator start-up timer
period) after the reset is detected and Fig.16 is the block diagram of reset. Once the RESET occurs,
the following functions are performed.
• The oscillator is running, or will be started.
• The Program Counter (R2) is set to all "1".
• When power is switched on, bits 5~6 of R3 and the upper 2 bits of R4 are cleared.
• All I/O port pins are configured as input mode (high-impedance state).
• The Watchdog timer and prescaler are cleared.
• The Watchdog timer is enabled if Code Option bit ENWDT is "1".
• The CONT register is set to all "1" except bit 6 (INT flag).
• Bits 3,6 of IOCE register are cleared, bits 0,4~5 of IOCE register are set to "1".
1
NOTE: Vdd = 5V, set up time period = 16.2ms ± 5%
Vdd = 3V, set up time period = 18.0ms ± 5%
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EM78P451
OTP ROM
• Bits 0 of R3F and bits 0 of IOCF registers are cleared.
The sleep mode (power down) is achieved by executing the SLEP instruction (named as SLEEP1
MODE). While entering sleep mode, the WDT (if enabled) is cleared but keeps on running. The
controller is awakened by WDT timeout (if enabled), and it will cause the controller to reset. The T and
P flags of R3 are used to determine the source of the reset (wake-up).
In addition to the basic SLEEP1 MODE, EM78P451 has another sleep mode (caused by clearing
"SLPC" bit of IOCE register, designated as SLEEP2 MODE). In the SLEEP2 MODE, the controller
can be awakened by-
(a) Any one of the wake-up pins is set to “0.” (refer to Fig.17). Upon waking, the controller will
continue to execute the program in-line. In this case, before entering SLEEP2 MODE, the wake-up
function of the trigger sources (P60~P67, P74~P75, and P90~P91)should be selected (e.g. input
pin) and enabled (e.g. pull-high, wake-up control). One caution should be noted is that after waking
up, the WDT is enabled if Code Option bit ENWDT is "1". The WDT operation (to be enabled or
disabled) should be appropriately controlled by software after waking up.
(b) WDT time-out (if enabled). On wake-up, will cause the controller reset.
Table 6 The Summary of the Initialized Values for Registers
Address Name Reset Type Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit Name C57 C56 C55 C54 C53 C52 C51 C50
N/A IOC5 Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name C67 C66 C65 C64 C63 C62 C61 C60
N/A IOC6 Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name C77 C76 C75 C74 C73 C72 C71 C70
N/A IOC7 Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name C87 C86 C85 C84 C83 C82 C81 C80
N/A IOC8 Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name C97 C96 C95 C94 C93 C92 C91 C90
N/A IOC9 Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name /PHEN /INT - - PAB PSR2 PSR1 PSR0
N/A CONT Power-On 1 0 1 1 1 1 1 1
/RESET and WDT 1 P 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name - - - - - - - -
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EM78P451
OTP ROM
0x00 R0(IAR) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name - - - - - - - -
0x01 R1(TCC) Power-On 0 0 0 0 0 0 0 0
/RESET and WDT 0 0 0 0 0 0 0 0
Wake-Up from Pin Change P P P P P P P P
Bit Name - - - - - - - -
0x02 R2(PC) Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change **P **P **P **P **P **P **P **P
Bit Name GP PS1 PS0 T P Z DC C
0x03 R3(SR) Power-On 0 0 0 t t U U U
/RESET and WDT 0 0 0 t t P P P
Wake-Up from Pin Change P P P t t P P P
Bit Name RSR.1 RSR.0 - - - - - -
0x04 R4(RSR) Power-On 0 0 U U U U U U
/RESET and WDT 0 0 P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name P57 P56 P55 P54 P53 P52 P51 P50
0x05 R5(P5) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name P67 P66 P65 P64 P63 P62 P61 P60
0x06 R6(P6) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name P77 P76 P75 P74 P73 P72 P71 P70
0x07 R7(P7) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name P87 P86 P85 P84 P83 P82 P81 P80
0x08 R8(P8) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name P97 P96 P95 P94 P93 P92 P91 P90
0x09 R9(P9) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name SRB7 SRB6 SRB5 SRB4 SRB3 SRB2 SRB1 SRB0
0x0A RA(SPIRB) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name SWB7 SWB6 SWB5 SWB4 SWB3 SWB2 SWB1 SWB0
0x0B RB(SPIWB) Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
Bit Name
0x0C RC(SPIS) Power-On 0 0 0 0 0 0 0 0
/RESET and WDT 0 0 0 0 0 0 0 0
Wake-Up from Pin Change P P P P P P P P
Bit Name CES SPIE SRO SPISE -
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ENSD
O
36
OBDC IBDC TIIF OD3 OD4 RBFIF RBF
SBRS2 SBRS1 SBRS
0
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EM78P451
OTP ROM
0x0D RD(SPIC) Power-On 0 0 0 0 0 0 0 0
/RESET and WDT 0 0 0 0 0 0 0 0
Wake-Up from Pin Change P P P P P P P P
Bit Name
0x0E RE(TMR1) Power-On 0 0 0 0 0 0 0 0
/RESET and WDT 0 0 0 0 0 0 0 0
Wake-Up from Pin Change P P P P P P P P
Bit Name PWP7 PWP6 PWP5 PWP4 PWP3 PWP2 PWP1 PWP0
0x0F RF(PWP) Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name - - - - T1IF SPIIF EXIF TCIF
0x3F R3F(ISR) Power-On U U U U 0 0 0 0
/RESET and WDT U U U U 0 0 0 0
Wake-Up from Pin Change U U U U P P P P
Bit Name - - - - - T1E T1P1 T1P0
0x0C IOCC Power-On 0 0 0 0 0 0 0 0
/RESET and WDT 0 0 0 0 0 0 0 0
Wake-Up from Pin Change P P P P P P P P
Bit Name S7 - - - /PU9 /PU8 /PU6 /PU5
0x0D IOCD Power-On 1 1 1 1 1 1 1 1
/RESET and WDT 1 1 1 1 1 1 1 1
Wake-Up from Pin Change P P P P P P P P
Bit Name - ODE WTE SLPC ROC - - /WUE
0x0E IOCE Power-On U 0 1 1 0 U U 1
/RESET and WDT U 0 1 1 0 U U 1
Wake-Up from Pin Change U P 1 1 P U U P
Bit Name - - - - T1IE SPIIE EXIE TCIE
0x0F IOCF Power-On U U U U 0 0 0 0
/RESET and WDT U U U U 0 0 0 0
Wake-Up from Pin Change U U U U P P P P
Bit Name - - - - - - - -
0x10~0x3E GPR Power-On U U U U U U U U
/RESET and WDT P P P P P P P P
Wake-Up from Pin Change P P P P P P P P
** To execute the next instruction after the ”SLPC” bit status of IOCE register being on high-to-low transition.
TMR17 TMR16 TMR15 TMR14 TMR13 TMR12 TMR11 TMR1
0
X: Not used. U: Unknown or don’t care.P: Previous value before reset. t: Check Table 7
The Status of RST, T, and P of STATUS Register
A RESET condition is initiated by the following events:
1. A power-on condition,
2. Watchdog timer time-out.
The values of T and P, listed in Table 7 are used to check how the processor wakes up.
Table 8 shows the events that may affect the status of T and P.
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Table 7 The Values of RST, T and P After RESET
Reset Type T P
Power on 1 1
WDT during Operating mode 0 P
WDT wake-up during SLEEP1 mode 0 0
WDT wake-up during SLEEP2 mode 0 P
Wake-Up on pin change during SLEEP2 mode P P
*P: Previous value before reset
Table 8 The Status of RST, T and P Being Affected by Events
Event T P
Power on 1 1
WDTC instruction 1 1
WDT time-out 0 *P
SLEP instruction 1 0
Wake-Up on pin change during SLEEP2 mode P P
EM78P451
OTP ROM
*P: Previous value before reset
4.8 Interrupt
The EM78P451 has the following interrupts.
1. /TCC overflow interrupt
2. External interrupt (/INT)
3. Serial Peripheral Interface (SPI) transmission completed interrupt.
4. Timer1 comparator completed interrupt.
R3F is the interrupt status register, which records the interrupt request in flag bit. IOCF is the interrupt
mask register. Global interrupt is enabled by ENI instruction and is disabled by DISI instruction. When
one of the interrupts (if enabled) is generated, will cause the next instruction to be fetched from address
001H. Once in the interrupt service routine the source of the interrupt can be determined by polling the
flag bits in the R3F register. The interrupt flag bit must be cleared by software before leaving the
interrupt service routine and enabling interrupts to avoid recursive interrupts.
The flag in the Interrupt Status Register (R3F) is set regardless of the status of its mask bit or the
execution of ENI instruction. Note that reading R3F will obtain the output of logic AND of R3F and IOCF
(refer to Fig. 17). The RETI instruction exits interrupt routine and enables the global interrupt (execution
of ENI instruction).
When an interrupt is generated by INT instruction (if enabled), it causes the next instruction to be
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fetched from address 002H.
EM78P451
OTP ROM
/IRQn
4.9 Oscillator
1. Oscillator Modes
The EM78P451 can operate in four different oscillator modes. There are high XTAL (HXT) oscillator
R3F
RESET
D
CLK
IOCFWR
IRQn
IRQm
interrupt
ENI/DISI
IOD
P
Q
R
C
Q
L
Q
Q
IOCF
P
R
CLK
C
L
IOCFRD
RFWR
RFRD
D
Fig. 17 Interrupt Input Circuit
mode, low XTAL (LXT) oscillator mode, External RC oscillator mode (ERC), and Internal C、External
R oscillator modes. User can select one of them by programming MS, RCT, IRC, HLF and HLP in the
Code Option Register. Table 9 depicts how these three modes are defined.
Table 9 Oscillator Modes by MS, IRC, RCT.
Mode MS IRC RCT HLF HLP
High XTAL Oscillator 1 X X 1 X
Low XTAL Oscillator 1 X X 0 0
External RC Oscillator 0 1 1 X X
External R and Internal C Oscillator 0 1 0 X X
<Note> X: Don’t care
2. Crystal Oscillator/Ceramic Resonators (XTAL)
EM78P451 can be driven by an external clock signal through the OSCI pin as shown in Fig 18 below.
In the most applications, pin OSCI and pin OSCO is connected with a crystal or ceramic resonator to
generate oscillation. Fig 19 depicts such circuit. Table 10 provides the recommended values of C1
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EM78P451
OTP ROM
and C2. Since each resonator has its own attribute, user should refer to its specification for
appropriate values of C1 and C2. RS, a serial resistor may be necessary for AT strip cut crystal or low
frequency mode.
OSCI
OSCO
EM78P451
Fig. 18 Circuit for External Clock Input
EM78P451
Fig. 19 Circuit for Crystal/Resonator
OSCI
OSCO
XTAL
RS
Ext. Clock
C1
C2
Table 10 Capacitor Selection Guide for Crystal Oscillator Ceramic Resonators
Oscillator Type Frequency Mode Frequency C1 (pF) C2 (pF)
455 KHz 10~150 10~150
Ceramic Resonator HXT
1.0 MHz 40~80 40~80
2.0 MHz 20~40 20~40
4.0 MHz 10~30 10~30
32.768 KHz 25 15
100 KHz 25 25 LXT
200 KHz 25 25
Crystal Oscillator
HXT
455 KHz 20~40 20~150
1.0 MHz 15~30 15~30
2.0 MHz 15 15
4.0 MHz 15 15
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EM78P451
OTP ROM
330 330
C
OSCI
EM78P451
7404
7404 7404
XTAL
Fig. 20 Circuit for Crystal/Resonator-Series Mode
OSCI
EM78P451
7404
10K
4.7K 10K
7404
XTAL
C1
C2
VDD
Fig. 21 Circuit for Crystal/Resonator-Parallel Mode
3. RC Oscillator Mode
For some applications that do not need a very precise timing calculation, the RC oscillator (Fig 22 &
Fig 23) offers a lot of cost savings. Nevertheless, it should be noted that the frequency of the RC
oscillator is influenced by the supply voltage, the values of the resistor (Rext), the capacitor (Cext),
and even by the operation temperature. Moreover, the frequency also changes slightly from one chip
to another due to the manufacturing process variation.
In order to maintain a stable system frequency, the values of the Cext should not be less than 20pF,
and that the value of Rext should not be greater than 1 M ohm. If they cannot be kept in this range, the
frequency is easily affected by noise, humidity, and leakage.
The smaller the Rext in the RC oscillator, the faster its frequency will be. On the contrary, for very low
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EM78P451
OTP ROM
Rext values, for instance, 1 KΩ, the oscillator becomes unstable because the NMOS cannot
discharge the current of the capacitance correctly.
Based on the reasons above, it must be kept in mind that all of the supply voltage, the operation
temperature, the components of the RC oscillator, the package types, the way the PCB is layout, will
affect the system frequency.
VCC
Rext
OSCI
EM78P451
Cext
Fig. 22 Circuit for External RC Oscillator Mode
VCC
Rext
OSCI
EM78P451
Fig. 23 Circuit for External R, Internal C Oscillator Mode
Calibrate frequency of External RC oscillator (For reference only)
C ext R ext
Fosc @5.0V,25℃
3.3K 3.4MHz
20pF
5.1K 2.2MHz
10K 1.3MHz
100K 144KHz
3.3K 1.39MHz
100pF
5.1K 935KHz
10K 500KHz
100K 54.5KHz
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EM78P451
OTP ROM
300pF
Internal C, external R Table (For reference only)
External R (Ohm)
3.3K 740KHz
5.1K 490KHz
10K 255KHz
100K 28KHz
Fosc @5.0V, 25℃ (Hz)
10K 12M
15K 7.7M
20K 5.7M
30K 3.65M
51K 2.24M
100K 1.14M
150K 749K
200K 559K
510K 214K
2M 56K
3.3M 32.8K
4.10. Code Option Register :
Address 12 11 10 9 8 7 6 5 4 3 2 1 0
0xFFF MS ENWDT CLKS PTB HLF RCT HLP DEL0 DEL1 ID3 ID2 ID1 ID0
• Bit 12 (MS): Oscillator type selection.
0: RC type
1: XTAL type
• Bit 11 (ENWDT): Watchdog Timer enabled.
0: Enable
1: Disable
• Bit 10 (CLKS): Clocks of each instruction cycle.
0: Two clocks
1: Four clocks
• Bit 9 (PTB): Protect bit.
0: Protect enabled
1: Protect disabled
• Bit 8 (HLF): XTAL frequency selection.
0: Low frequency (32.768KHz)
1: High frequency
This bit is useful only when Bit 12 (MS) is 1. When MS is 0, HLF must be 0.
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• Bit 7 (RCT): Resistor Capacitor.
0: internal RC
1: external RC
• Bit 6 (HLP): Power consumption selection.
0: Low power
1: High power
• Bit 5 ~ Bit 4: DEL1 and DEL0 (SDI) input delay time options.
DEL 1 DEL 0 Delay time
1 1 0 ns
0 1 50 ns
1 0 100 ns
• Bit3~0 (ID): User’s ID code.
EM78P451
OTP ROM
• Procedures to configure the RC oscillators by programming the option code:
i. Enable External RC oscillator:
MS (0) -> IRC (1) -> RCT (1)
ii. Enable External R and Internal C oscillator:
•MS (0) -> IRC (1) -> RCT (0)
4.11 Instruction Set
Each instruction in the instruction set is a 13-bit word divided into an OP code and one or more
operands. All instructions are executed within one single instruction cycle (consisting of 2 oscillator
periods), unless the program counter is changed by-
(a) Executing the instruction "MOV R2,A", "ADD R2,A", "TBL", or any other instructions that write to
R2 (e.g. "SUB R2,A", "BS R2,6", "CLR R2", ⋅⋅⋅⋅).
(b) execute CALL, RET, RETI, RETL, JMP, Conditional skip (JBS, JBC, JZ, JZA, DJZ, DJZA) which
were tested to be true.
Under these cases, the execution takes two instruction cycles.
In addition, the instruction set has the following features:
(1). Every bit of any register can be set, cleared, or tested directly.
(2). The I/O register can be regarded as general register. That is, the same instruction can operate
on I/O register.
The symbol "R" represents a register designator that specifies which one of the registers (including
operational registers and general purpose registers) is to be utilized by the instruction. Bits 6 and 7 in
R4 determine the selected register bank. "b" represents a bit field designator that selects the value for
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EM78P451
OTP ROM
the bit located in the register "R" and affects operation. "k" represents an 8 or 10-bit constant or literal
value.
INSTRUCTION BINARY HEX MNEMONIC OPERATION STATUS AFFECTED
0 0000 0000 0000 0000 NOP No Operation None
0 0000 0000 0001 0001 DAA Decimal Adjust A C
0 0000 0000 0010 0002 CONTW
0 0000 0000 0011 0003 SLEP
0 0000 0000 0100 0004 WDTC
0 0000 0000 rrrr 000r IOW R
0 0000 0001 0000 0010 ENI Enable Interrupt None
0 0000 0001 0001 0011 DISI Disable Interrupt None
0 0000 0001 0010 0012 RET
0 0000 0001 0011 0013 RETI
0 0000 0001 0100 0014 CONTR
0 0000 0001 rrrr 001r IOR R
0 0000 0010 0000 0020 TBL
0 0000 01rr rrrr 00rr MOV R,A
0 0000 1000 0000 0080 CLRA
0 0000 11rr rrrr 00rr CLR R
0 0001 00rr rrrr 01rr SUB A,R
0 0001 01rr rrrr 01rr SUB R,A
0 0001 10rr rrrr 01rr DECA R
0 0001 11rr rrrr 01rr DEC R
0 0010 00rr rrrr 02rr OR A,R
0 0010 01rr rrrr 02rr OR R,A
0 0010 10rr rrrr 02rr AND A,R
0 0010 11rr rrrr 02rr AND R,A
0 0011 00rr rrrr 03rr XOR A,R
0 0011 01rr rrrr 03rr XOR R,A
0 0011 10rr rrrr 03rr ADD A,R
0 0011 11rr rrrr 03rr ADD R,A
0 0100 00rr rrrr 04rr MOV A,R
0 0100 01rr rrrr 04rr MOV R,R
0 0100 10rr rrrr 04rr COMA R
0 0100 11rr rrrr 04rr COM R
0 0101 00rr rrrr 05rr INCA R
0 0101 01rr rrrr 05rr INC R
0 0101 10rr rrrr 05rr DJZA R
0 0101 11rr rrrr 05rr DJZ R
0 0110 00rr rrrr 06rr RRCA R
0 0110 01rr rrrr 06rr RRC R
0 0110 10rr rrrr 06rr RLCA R
0 0110 11rr rrrr 06rr RLC R
0 0111 00rr rrrr 07rr SWAPA R
A → CONT
0 → WDT, Stop oscillator
0 → WDT
A → IOCR
[Top of Stack] → PC
[Top of Stack] → PC,
Enable Interrupt
CONT → A
IOCR → A
R2+A → R2,
Bits 8~9 of R2 unchanged
A → R
0 → A
0 → R
R-A → A
R-A → R
R-1 → A
R-1 → R
A ∨ VR → A
A ∨ VR → R
A & R → A
A & R → R
A ⊕ R → A
A ⊕ R → R
A + R → A
A + R → R
R → A
R → R
/R → A
/R → R
R+1 → A
R+1 → R
R-1 → A, skip if zero
R-1 → R, skip if zero
R(n) → A(n-1),
R(0) → C, C → A(7)
R(n) → R(n-1),
R(0) → C, C → R(7)
R(n) → A(n+1),
R(7) → C, C → A(0)
R(n) → R(n+1),
R(7) → C, C → R(0)
R(0-3) → A(4-7),
R(4-7) → A(0-3)
None
T,P
T,P
None <Note1>
None
None
None
None <Note1>
Z,C,DC
None
Z
Z
Z,C,DC
Z,C,DC
Z
Z
Z
Z
Z
Z
Z
Z
Z,C,DC
Z,C,DC
Z
Z
Z
Z
Z
Z
None
None
C
C
C
C
None
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EM78P451
OTP ROM
INSTRUCTION BINARY HEX MNEMONIC OPERATION STATUS AFFECTED
0 0111 01rr rrrr 07rr SWAP R R(0-3) ↔ R(4-7) None
0 0111 10rr rrrr 07rr JZA R
0 0111 11rr rrrr 07rr JZ R
0 100b bbrr rrrr 0xxx BC R,b
0 101b bbrr rrrr 0xxx BS R,b
0 110b bbrr rrrr 0xxx JBC R,b if R(b)=0, skip None
0 111b bbrr rrrr 0xxx JBS R,b if R(b)=1, skip None
1 00kk kkkk kkkk 1kkk CALL k
1 01kk kkkk kkkk 1kkk JMP k
1 1000 kkkk kkkk 18kk MOV A,k
1 1001 kkkk kkkk 19kk OR A,k
1 1010 kkkk kkkk 1Akk AND A,k
1 1011 kkkk kkkk 1Bkk XOR A,k
1 1100 kkkk kkkk 1Ckk RETL k
1 1101 kkkk kkkk 1Dkk SUB A,k
1 1110 0000 0010 1E02 INT
1 1111 kkkk kkkk 1Fkk ADD A,k
<Note1> This instruction is applicable to IOC5 ~ IOC9, IOCD~IOCF only.
R+1 → A, skip if zero
R+1 → R, skip if zero
0 → R(b)
1 → R(b)
PC+1 → [SP],
(Page, k) → PC
(Page, k) → PC
k → A
A ∨ k → A
A & k → A
A ⊕ k → A
k → A, [Top of Stack] → PC
k-A → A
PC+1 → [SP], 002H → PC
k+A → A
None
None
None <Note2>
None <Note3>
None
None
None
Z
Z
Z
None
Z,C,DC
None
Z,C,DC
<Note2> This instruction is not recommended for RF operation.
<Note3> This instruction cannot operate on R3F.
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4.12 Timing Diagrams
AC Test Input/Output Waveform
EM78P451
OTP ROM
2.4
0.4
AC Testing : Input is driven at 2.4V for logic "1",and 0.4V for logic "0".Timing measurements are
made at 2.0V for logic "1",and 0.8V for logic "0".
2.0
0.8
TEST POINTS
2.0
0.8
RESET Timing (CLK="0")
NOP
CLK
/RESET
Instruction 1
Executed
Tdrh
TCC Input Timing (CLKS="0")
Tins
CLK
TCC
Ttcc
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5. ABSOLUTE MAXIMUM RATING
Items Rating
Temperature under bias
Storage temperature -65°C to 150°C
Input voltage -0.3V to +6.0V
Output voltage -0.3V to +6.0V
Operating Frequency (2clk) DC to 20MHz
0°C
to
EM78P451
OTP ROM
70°C
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EM78P451
OTP ROM
6. ELECTRICAL CHARACTERISTICS
(1) DC Characteristic
(Ta=0°C~70°C, VDD=5V±5%, VSS=0V)
Symbol Parameter Condition Min Typ Max Unit
XTAL VDD to 2.3V DC 4
FXT
FRC
IIL Input Leakage Current VIN = VDD, VSS ±1 µA
VIH1 Input High Voltage VDD=5V)
VIL1 Input Low Voltage (VDD=5V)
VIHX1
VILX1
VIH2 Input High Voltage(VDD=3V)
VIL2 Input Low Voltage (VDD=3V)
VIHX2
VILX2
VOH1
VOH2
VOH3
VOL1
VOL2
VOL3
XTAL VDD to 3V DC 8
XTAL VDD to 5V
RC VDD to 2.3V DC 4
RC VDD to 3V DC 4
RC VDD to 5V
Clock Input High Voltage
Clock Input Low Voltage
Clock Input High Voltage
Clock Input Low Voltage
(Ports 5,6,8, P74~P77,
P90~P92,P95~P97,and
(Ports 5,6,8, P74~P77,
P90~P92,P95~P97,and
(VDD=5V)
(VDD=5V)
(VDD=3V)
(VDD=3V)
Output High Voltage
PF5~PF7)
Output High Voltage
(P70~P72)
Output High Voltage
(P93/SDO,P94/SCK)
Output Low Voltage
PF5~PF7))
Output Low Voltage
(P70~P72)
Output Low Voltage
(P93/SDO, P94/SCK)
S7=1(IOCD Register bit7),
S7=0(IOCD Register bit7),
S7=1(IOCD Register bit7),
S7=0(IOCD Register bit7),
Two clocks
DC 20
Two clocks
DC 4
2.0 V
0.8 V
OSCI 2.5 V
OSCI 1.0 V
1.5 V
0.4 V
OSCI 1.5 V
OSCI 0.6 V
IOH = -8.0mA 2.4 V
IOH = -7.0mA
IOH = -7.0mA
IOH = -5.0mA 2.4 V
IOL = 5.0mA 0.4 V
IOH = 10.0mA
IOH = 10.0mA
IOL = 7.0mA 0.4 V
2 2.4
2.4
0.4 0.8
0.4
MHz
MHz
V
V
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EM78P451
All input and I/O pin at VDD, output
OTP ROM
VOL4
IPH Pull-high current Pull-high active, input pin at VSS -50 -100 -240 µA
IPH2
ISB Power down current
ICC Operating supply current
Output Low Voltage
(2) AC Characteristic
(Ta=0°C~70°C, VDD=5V±5%, VSS=0V)
Symbol Parameter Conditions Min Typ Max Unit
Dclk Input CLK duty cycle 45 50 55 %
Tins
Ttcc TCC input period (Tins+20)/N* ns
Twdt Watchdog timer period Ta=25°C 18 ms
Tdrh Device reset hold period Ta=25°C 181 ms
N= selected prescaler ratio.
Instruction cycle time
(P74~P77)
Pull-high current
(P74,P75)
(CK2="0")
IOL = 15.0mA 0.4
Pull-high active, input pin at VSS 1 mA
pin floating, WDT enabled
/RESET="High",
Fosc=1.84324MHz (CK2="0"),
output pin floating
RC Type 500 DC ns
10 µA
3 mA
1
NOTE: Vdd = 5V, set up time period = 16.2ms ± 5%
Vdd = 3V, set up time period = 18.0ms ± 5%
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7. Application Circuit
EM78P451
EM78P451
OTP ROM
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APPENDIX
Package Types:
OTP MCU Package Type Pin Count Package Size
EM78P451P DIP 40 600 mil
EM78P451AQ QFP 44
EM78P451
OTP ROM
This specification is subject to change without prior notice. 2002/03/01
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