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R9M Inverter Mod

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  • To benefit from the higher bitrate of 400 kilobits per second using OpenTX/EdgeTX you need to add a pull-up resistor to the inverter of the serial port on the R9M 2018🗻🆙
  • Strongly suggested being done for anybody looking for higher than standard packet rates using ExpressLRS 🔮


⚠️ This is only required for the 2018 version of the module which has a ACCST logo on the case 🔍


Easy - connect a 300Ω to 1000Ω resistor between the 3.3V and inverter pin as shown in the picture 👧

resistor mod

Transmitter Notes

Some Radios/Transmitters will require the Inverter/Crossfire Mod depending on the Baud Rate you want to use or you can use.

Radio Baud Rate Inverter/Crossfire Mod R9M ACCST MOD Other Notes
X9D 400000 Not Needed Required See Troubleshooting
X10S Express 400000 Not Needed Required -
X10S 400000 Required. Modding Guide. Required -
X12 400000 Required. Modding Guide. Required -
QX7 400000 Required. Modding Guide. Required See Troubleshooting
QX7 115200 Not Needed Not Needed Max Packet Rate supported is 250Hz
Others 400000+ Not Needed Required TX16S, TX12, T16/T18, etc

ACCESS radios don't need the Inverter/Crossfire mod.