We have already uploded the betaflight firmware. If you use betaflight, you don’t need to upload the firmware.
If you want to upload firmware, upload this version firmware. Select OMNIBUSF4SD
If you use betaflight-configurator to upload the latest firmware, should click ‘Apply Custom Defaults’ button.
1. betaflight-configurator: https://github.com/betaflight/betaflight-configurator/releases
2. cleanflight -configurator :https://github.com/cleanflight/cleanflight-configurator/releases
4.How to upload inav firmware for F4V3S? http://blog.rctoysky.com/?p=423
5.Use UART1 for external GPS if you use GPS.
Use UART6 for remote control receiver (PPMor SBUS)