I have a project where I need one board, lets call it the master, that can communicate via rs232 to multiple slaves. The slaves must each be able to receive and transmit, but only to the master, and only when first addressed by the master. Thus I have connected it this way:
I have the code completed and some prototypes, and it all works except one thing. If I have more than 1 slave board connected, slave transmissions fail. This is because the MAX232 chips on the slave boards hold the slave's transmit pin (and thus the Master's Receive Pin) at -5.4V (RS232 output when idle) such that the other slave cannot send data.
So what's the best method of countering this problem? There's no way to turn off the transmit pin of the MAX232 chip. So I need a switch of some sort on the MAX232 txout pin. This is tricky for me because the microcontroller and other devices work at 3.3V.
Thanks!
Rich (BB code):
Master Slave1 Slave2
TxPin-----RxPin-----RxPin
RxPin-----TxPin-----TxPin
Gnd-------Gnd-------Gnd
So what's the best method of countering this problem? There's no way to turn off the transmit pin of the MAX232 chip. So I need a switch of some sort on the MAX232 txout pin. This is tricky for me because the microcontroller and other devices work at 3.3V.
Thanks!