Now, I having a problem with the protocol RS232 to RS485. I posted my schematic and could any body help me check it?
follow this circuit, when I brake pin 9 (MAX232) and connect to VCC or GND, transmit and receive was OK. But I keep intact this pin's connect, I couldn't transmit or receive...:?:
Please help me!
My project was designed: PC (master) <--> AVR (slaver1) <--> AVR (slaver2) throught MAX485.
The key factor in the successfull RS232-to-RS485 conversion is in the correct switching between transmission and reception ..
If you can't use RTS signal to control the DE-/RE pins than the whole idea of using MAX232 and MAX485 (including option with MOSFET transistor) won't work ..
Here is another (working!!!) option:
Take a look at it and if you have further questions - come back ..