Hello,
The micro controller is named as P89C51RD2 IS THAT SAME FOR 8051?
and you are not using pin7?
and are you sir using software based I2C?
writeRTC: ; R2 = byte address.. R1 = data
acall startc
mov a,#0D0h ; RTC address
acall Send
acall ack ; Get ack
mov a,R2 ; register address
acall Send
acall ack
mov a,R1 ; send data
acall Send
acall ack
acall stop
ret
readRTC:
acall startc
mov a,#0D0h ; Device address
acall Send
acall ack
mov a,R2 ; Register address
acall Send
acall ack
acall rstart
mov a,#0D1h ; Read command
acall Send
acall ack
acall recv
mov R1,a ; Get data
acall nak
acall stop
ret