The W78E58 is an 8-bit microcontroller that is functionally compatible with the W78C58, except that
the mask ROM is replaced by a flash EEPROM with a size of 32 KB. To facilitate programming and
verification, the flash EEPROM inside the W78E58 allows the program memory to be programmed
and read electronically. Once the code is confirmed, the user can protect the code for security.
The W78E58 microcontroller supplies a wider frequency range than most 8-bit microcontrollers on the
market. It is functionally compatible with the industry-standard 80C52 microcontroller series, except
that one extra 4-bit bit-addressable I/O port(Port 4) and two additional external interrupts (
INT3 ).
The W78E58 contains four 8-bit bi-directional and bit-addressable I/O ports, three 16-bit
timer/counters, and a serial port. These peripherals are supported by a eight-source, two-level
interrupt capability. There are 256 bytes of RAM and an 32 KB flash EEPROM for application
programs.
The W78E58 microcontroller has two power reduction modes, idle mode and power-down mode, both
of which are software selectable. The idle mode turns off the processor clock but allows for continued
peripheral operation. The power-down mode stops the crystal oscillator for minimum power
consumption. The external clock can be stopped at any time and in any state without affecting the
processor.
,
FEATURES
• 8-bit CMOS microcontroller
• Fully static design
• Low standby current at full supply voltage
• DC-40 MHz operation
• 256 bytes of on-chip scratchpad RAM
• 32 KB electrically erasable/programmable EPROM
• 64 KB program memory address space
• 64 KB data memory address space
• Four 8-bit bidirectional ports
• One extra 4-bit bit-addressable I/O port, additional
The W78E58 has two operating modes, normal and flash. In normal mode, the W78E58 corresponds
to the W78C58. In flash mode, the user (the maker of the flash EEPROM writer) can access the flash
EEPROM.
P0.7−P0.0 Port 0, Bits 7−0
MODEDESCRIPTION
NormalPort 0, Bits 0 through 7. Port 0 is a bidirectional I/O port. This port also provides a
multiplexed low order address/data bus during accesses to external memory.
FlashThis port provides the data bus during access to the flash EEPROM.
P1.7−P1.0 Port 1, Bits 7−0
MODEDESCRIPTION
NormalPort 1, Bits 0 through 7. Port 1 is a bidirectional I/O port with internal pull-ups. Pins
P1.0 and P1.1 also serve as T2 (Timer 2 external input) and T2EX (Timer 2
capture/reload trigger), respectively.
FlashThis port provides the low-order address bus during access to the flash EEPROM.
P2.7−P2.0 Port 2, Bits 7−0
MODEDESCRIPTION
NormalPort 2, Bits 0 through 7. Port 2 is a bidirectional I/O port with internal pull-ups. This port
also provides the upper address bits for accesses to external memory..
FlashThis port provides the high-order address bus during access to the flash EEPROM.
P3.7−P3.0 Port 3, Bits 7−0
MODEDESCRIPTION
NormalPort 3, Bits 0 through 7. Port 3 is a bidirectional I/O port with internal pull-ups. All bits
have alternate functions.
Flash
P3.3−P3.0 and P3.7−P3.6 are the flash mode configuration pins, Input.
P3.3−P3.0 and P3.7−P3.6 are configured to select or execute the flash operations. For
details, see Flash Operations.
P4.3−P4.0 Port 4, Bits 3−0 (available on 44-pin PLCC/QFP package)
MODEDESCRIPTION
NormalAnother bit-addressable bidirectional I/O port P4. P4.3 and P4.2 are alternative
function pins. It can be used as general I/O pins or external interrupt input sources
(
/ INT3 ).
Publication Release Date: November 1997
- 3 -Revision A2
FlashNo function in this mode.
EA
PSEN
This pin
PSEN
PSEN
EA/VPP
MODEDESCRIPTION
W78E58
Normal
FlashVPP, Program Power supply pin, Input.
External Access, Input, active low.
,
This pin forces the processor to execute a program from the external ROM. When the
internal flash EEPROM is accessed as in the W78C58, this pin should be kept high.
This pin accepts the high voltage (12V) needed for programming the flash EEPROM.
RST
MODEDESCRIPTION
NormalRST, Reset, Input, active high.
This pin resets the processor. It must be kept high for at least two machine cycles in
order to be recognized by the processor.
FlashFlash mode configuration pin, Input, active high.
RST is used to configure the flash operations. For details, see Flash Operations.
ALE
MODEDESCRIPTION
Normal
FlashFlash mode configuration pin, Input, active low.
Address Latch Enable, Output, active high.
ALE,
ALE is used to enable the address latch that separates the address from the data on
Port 0. ALE runs at 1/6th of the oscillator frequency. A single ALE pulse is skipped
during external data memory accesses. ALE goes to a high impedance state with a
weak pull-up during reset state.
ALE is used to configure the flash operations. For details, see Flash Operations.
PSEN
MODEDESCRIPTION
Normal
MOVC operations.
reset state
FlashFlash mode configuration pin, Input, active high.
Program Store Enable, Output, active low.
,
enables the external ROM onto the Port 0 address/data bus during fetch and
goes to a high impedance state with a weak pull-up during
is used to configure the flash operations. For details, see Flash Operations.
XTAL1
MODEDESCRIPTION
- 4 -
W78E58
NormalCrystal 1. This is the crystal oscillator input. This pin may be driven by an external
clock.
FlashConnect to VSS.
XTAL2
MODEDESCRIPTION
NormalCrystal 2. This is the crystal oscillator output. It is the inversion of XTAL1.
FlashNo function in this mode.
VSS, VCC
Power Supplies. These are the chip ground and positive supplies.
Publication Release Date: November 1997
- 5 -Revision A2
BLOCK DIAGRAM
P1.0
~
P1.7
Port
1
W78E58
Port 1
Latch
P3.0
~
P3.7
P4.0
~
P4.3
INT2
INT3
Port
Port
T2
SFR RAM
Address
256 bytes
RAM & SFR
B
Stack
Pointer
Power Control
Port 0
Latch
DPTR
Temp Reg.
PC
Incrementor
Addr. Reg.
Port 2
Latch
Port
0
Port
2
P0.0
~
P0.7
P2.0
~
P2.7
ACC
Interrupt
PSW
Instruction
Decoder
&
Sequencer
Bus & Clock
Controller
T1
ALU
Reset Block
Timer
2
Timer
0
Timer
1
UART
3
4
Port 3
Latch
Port 4
Latch
Oscillator
XTAL1
XTAL2
ALE
PSEN
RST
- 6 -
VssVcc
W78E58
FUNCTIONAL DESCRIPTION
The W78E58 architecture consists of a core controller surrounded by various registers, five general
purpose I/O ports, 256 bytes of RAM, three timer/counters, and a serial port. The processor supports
111 different opcodes and references both a 64K program address space and a 64K data storage
space.
Timers 0, 1, and 2
Timers 0, 1, and 2 each consist of two 8-bit data registers. These are called TL0 and TH0 for Timer 0,
TL1 and TH1 for Timer 1, and TL2 and TH2 for Timer 2. The TCON and TMOD registers provide
control functions for timers 0 and 1. The T2CON register provides control functions for Timer 2.
RCAP2H and RCAP2L are used as reload/capture registers for Timer 2.
The operations of Timer 0 and Timer 1 are the same as in the W78C51. Timer 2 is a special feature
of the W78E58: it is a 16-bit timer/counter that is configured and controlled by the T2CON register.
Like Timers 0 and 1, Timer 2 can operate as either an external event counter or as an internal timer,
depending on the setting of bit C/T2 in T2CON. Timer 2 has three operating modes: capture, autoreload, and baud rate generator. The clock speed at capture or auto-reload mode is the same as that
of Timers 0 and 1.
Clock
The W78E58 is designed to be used with either a crystal oscillator or an external clock. Internally, the
clock is divided by two before it is used. This makes the W78E58 relatively insensitive to duty cycle
variations in the clock.
Crystal Oscillator
The W78E58 incorporates a built-in crystal oscillator. To make the oscillator work, a crystal must be
connected across pins XTAL1 and XTAL2. In addition, a load capacitor must be connected from each
pin to ground, and a resistor must also be connected from XTAL1 to XTAL2 to provide a DC bias
when the crystal frequency is above 24 MHz.
External Clock
An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The
XTAL1 input is a CMOS-type input, as required by the crystal oscillator. As a result, the external clock
signal should have an input one level of greater than 3.5 volts.
Power Management
Idle Mode
The idle mode is entered by setting the IDL bit in the PCON register. In the idle mode, the internal
clock to the processor is stopped. The peripherals and the interrupt logic continue to be clocked. The
processor will exit idle mode when either an interrupt or a reset occurs.
Power-down Mode
When the PD bit of the PCON register is set, the processor enters the power-down mode. In this
mode all of the clocks are stopped, including the oscillator. The only way to exit power-down mode is
by a reset.
Publication Release Date: November 1997
- 7 -Revision A2
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