multimodule serial on opentx

[josephdouce]

mike did you have to do anything different with the 9xrpro as they're having difficulty getting the serial control working on the opentx 9xrpro, I switched to ersk9xr and everything was working great, the issue is they don't have a 9xr pro to test on.

[MikeB]

Nothing special compared to the AR9X/SKY board. The output control data is exactly the same. The only real difference is handling the telemetry/status data coming back in. The 9XR-PRO includes a programmable, hardware inverter on this signal, so handles either polarity easily. The only 'problem' with that is the control signal for selecting the inversion comes from the RTC chip, so needs a transaction on the I2C bus to set it as required.

Mike.

[Kilrah]

The solution was simple, the multimodule just needs push-pull output mode selected instead of open drain.