W741L250 Datasheet, PDF (20/86 Pages) Winbond – 4-BIT MICROCONTROLLER

W741L250
External INT
The external interrupt INT pin contains a pull-up resistor. When the HEF.4 or IEF.4 flag is set, the
falling edge of the INT pin will execute the hold mode release or interrupt subroutine. A low level on
the INT pin will release the stop mode.
Input/Output Ports RA, RB
Port RA consists of pins RA.0 to RA.3 and port RB consists of pins RB.0 to RB.3. After initial reset,
input/output ports RA and RB are both in input mode. When RA and RB are used as output ports,
CMOS or NMOS open drain output type can be selected by the PM0 register. Each pin of port RA or
RB can be specified as input or output mode independently by the PM1 and PM2 registers. The
MOVA R, RA or MOVA R, RB instructions operate the input functions and the MOV RA, R or MOV
RB, R operate the output functions. For more details, refer to the instruction table and Figure 9.
Input/Output Pin of the RA(RB)
V_DD
PM0.0 (or PM0.1)
DATA
BUS
Output
Buffer
Enable
MOV RA, R
(or MOV RB, R)
Instruction
PM1.n
(or PM2.n)
Enable
MOVA R, RA
(or MOVA R, RB)
instruction
I/O PIN
RA.n(RB.n)
Figure 9. Architecture of Input/Output Pins
Input Ports RC, RD
Port RC consists of pins RC.0 to RC.3, and port RD consists of pins RD.0 to RD.3. Each pin of port
RC and port RD can be connected to a pull-up resistor, which is controlled by the port mode 0 register
(PM0). When the PEF, HEF, and IEF corresponding to the RC port are set, a signal change on the
specified pins of port RC will execute the hold mode release or interrupt subroutine. Port status
register 0 (PSR0) records the status of ports RC, i.e., any signal changes on the pins that make up
the port. PSR0 can be read out and cleared by the MOV R, PSR0, and CLR PSR0 instructions. In
addition, the falling edge signal on the pin of port RC specified by the instruction MOV SEF, #I will
cause the device to exit the stop mode. Refer to Figure 10 and the instruction table for more details.
The RD port is used as input port only, it has no hold mode release, wake-up stop mode or interrupt
functions.
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