Abov MC96F6332D, User Manual

Page: 321 / 327

MC96F6432
June 22, 2018 Ver. 2.9 321
B. Instructions on how to use the input port.

Error occur status

Using compare jump instructions with input port, it could cause error due to the timing conflict inside the
MCU.

Compare jump Instructions which cause potential error used with input port condition:
JB bit, rel ; jump on direct bit=1
JNB bit, rel ; jump on direct bit=0
JBC bit, rel ; jump on direct bit=1 and clear
CJNE A, dir, rel ; compare A, direct jne relative
DJNZ dir, rel ; decrement direct byte, jnz relative

It is only related with Input port. Internal parameters, SFRs and output bit ports don
’t cause any error by
using compare jump instructions.

If input signal is fixed, there is no error in using compare jump instructions.

Error status example

Preventative measures (2 cases)

Do not use input bit port for bit operation but for byte operation. Using byte operation instead of bit oper
ation will not cause any error in using compare jump instructions for input port.
while(1){
if (P00==1) { P10=1; }
else { P10=0; }
P11^=1;
}
zzz: JNB 080.0, xxx ; it possible to be error
SETB 088.0
SJMP yyy
xxx: CLR 088.0
yyy: MOV C,088.1
CPL C
MOV 088.1,C
SJMP zzz
unsigned char ret_bit_err(void)
{
return !P00 ;
}
MOV R7, #000
JB 080.0, xxx ; it possible to be error
MOV R7, #001
xxx: RET
while(1){
if ((P0&0x01)==0x01) { P10=1; }
else { P10=0; }
P11^=1;
}
zzz: MOV A, 080 ; read as byte
JNB 0E0.0, xxx ; compare
SETB 088.0
SJMP yyy
xxx: CLR 088.0
yyy: MOV C,088.1
CPL C
MOV 088.1,C
SJMP zzz