[Moved] Serial Communication Problem in 8051 using MAX-485

[Briez]

-> I want to interface serial communication between 89s52 and hyper terminal..
-> I have made circuit like this...


-> I am making P3_2 pin high before sending frame and after sent making it low.
-> Is this right procedure? if not then tell me the right procedure for communication to computer.
-> Please help me to sort out this problem.

 

[FvM]

Re: Serial Communication Problem in 8051 using MAX-485

after sent making it low

Should be understand as after the TX buffer is empty. This can be e.g. determined by polling the TI flag or in an interrupt based TX routine.

As an additional point, RS485 usually requires pull-up/pull-down resistors for a correct bus idle state.