How can I connect one uart (arduino or raspberry pi) to a RS485 half duplex network. The protocol will be MODBUS (only one device communicating at the same time) The main problem is how to control DE/RE pin to switch between receiver and transmitter. In this case, I haven't got any control signal: only tx, rx and gnd. Well, I'm thinking about 3 options:
- Using one arduino to get data with one serial port and resend data with other serial port, enabling or disabling DE/RE. This option seems to be "expensive"
- Using a 555 timer to control a delayed signal to DE/RE. As seen in http://www.lvr.com/rs-485_circuits.htm
- Using a MAX13487E/MAX13488E transceiver with auto direction. Is there a 3v3 version of this chip?
Have you got any experience in this way?
Thanks a lot.