W742S81A Datasheet, PDF (25/47 Pages) Winbond – 4 BIT MICROCONTROLLER

W742S81A
6.16 Reset Function
The W742S81A is reset either by a power-on reset or by using the external RES pin. The initial state of
the W742S81A after the reset function is executed is described below.
Program Counter (PC)
WDTR registers
BUZCR registers
ACC, CF, ZF registers
MR0, MR1, PAGE registers
PSR0, SCR, TM0, TM1 registers
IEF, HEF, HCF, PEF, EVF, SEF flags
WRP, DBKR, PAGE registers
Timer 0 input clock
Timer 1 input clock
MFP output
DTMF output
Input/output ports RA, RB, RD
Output port RE & RF
RA, RB ports output type
RC ports pull-high resistors
Input clock of the watchdog timer
LCD display
000H
Reset
Reset
Reset
Reset
Reset
Reset
Reset
FOSC/4
FOSC
Low
Hi-Z
Input mode
High
CMOS type
Disable
FOSC/2048
OFF
Table 4 The initial state after the reset function is executed
6.17 Input/Output Ports RA, RB & RD
Port RA consists of pins RA.0 to RA.3. Port RB consists of pins RB.0 to RB.3. Port RD consists of pins
RD.0 to RD.3. At initial reset, input/output ports RA, RB and RD are all in input mode. When RA, RB
are used as output ports, CMOS or NMOS open drain output type can be selected by the PM0 register. But
when RD is used as output port, the output type is just fixed to be CMOS output type. Each pin of port RA,
Publication Release Date: March 2003
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Revision A1