W921E840A Datasheet, PDF (40/58 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E840A/W921C840
STPRF register: (address = 035H, default data = 8H)
b3
b2
b1
b0
0: Stop released by any pin of PA is disable
1: Stop released by any pin of PA is enable
0: Stop released by any pin of PB is disable
1: Stop released by any pin of PB is enable
0: Stop released by any pin of P4.0 to P4.2 is disable
1: Stop released by any pin of P4.0 to P4.2 is enable
0: Stop released by INT0 (P4.3) is disable
1: Stop released by INT0 (P4.3) is enable
When stop mode is active, if the stop condition release flag (STPRF) is set before the STOP
instruction is executed, the low level signal on the P4, PA or PB ports will release the stop mode and
a delay of 256 machine cycles occurs right after the stop mode is released, then the next instruction
is executed or the program counter (PC) jumps to interrupt subroutine if the interrupt is enabled and
interrupt request exists.
The control flow chart is shown below:
Stop mode operation flow chart
START
Enter STOP Mode
PC
STOP
STOP
No
Release
Yes
System will Delay 256
Machine Cycle
Automatically
Yes
(Only falling signal on
INT0 or P4.0 - P4.2)
INT Enable?
No
(PA, PB Ports on
low level state)
INT Vector
PC + 1
Next
Instruction
RTNI
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