atbetaflight/docs/Configuration.md

Serial port functions and scenarios

Serial port scenarios

0   UNUSED
1   MSP, CLI, TELEMETRY, GPS-PASTHROUGH
2   GPS ONLY
3   RX SERIAL ONLY
4   TELEMETRY ONLY
5   MSP, CLI, GPS-PASTHROUGH
6   CLI ONLY
7   GPS-PASSTHROUGH ONLY
8   MSP ONLY

Contraints

• There must always be a port available to use for MSP
• There must always be a port available to use for CLI
• To use a port for a function, the function's corresponding feature must be enabled first. e.g. to use GPS enable the GPS feature.
• If the configuration is invalid the serial port configuration will reset to it's defaults and features may be disabled.

Examples

All examples assume default configuration (via cli defaults command)

a) GPS and TELEMETRY (when armed)

• TELEMETRY,MSP,CLI,GPS PASSTHROUGH on UART1
• GPS on UART2

feature TELEMETRY
feature GPS
save

b) RX SERIAL and TELEMETRY (when armed)

• TELEMETRY,MSP,CLI,GPS PASSTHROUGH on UART1
• RX SERIAL on UART2

feature -RX_PARALLEL_PWM
feature RX_SERIAL
feature TELEMETRY
set serial_port_2_scenario = 3
save

b) RX SERIAL and TELEMETRY via softserial

• MSP,CLI,GPS PASSTHROUGH on UART1
• RX SERIAL on UART2
• TELEMETRY on SOFTSERIAL1

feature -RX_PARALLEL_PWM
feature RX_SERIAL
feature TELEMETRY
feature SOFTSERIAL
set serial_port_2_scenario = 3
set serial_port_3_scenario = 4
save

c) GPS and TELEMETRY via softserial

• MSP,CLI,GPS PASSTHROUGH on UART1
• GPS on UART2
• TELEMETRY on SOFTSERIAL1

feature -RX_PARALLEL_PWM
feature RX_PPM
feature TELEMETRY
feature GPS
feature SOFTSERIAL
set serial_port_3_scenario = 4
save

d) RX SERIAL, GPS and TELEMETRY (when armed) MSP/CLI via softserial

• GPS on UART1
• RX SERIAL on UART2
• TELEMETRY,MSP,CLI,GPS PASSTHROUGH on SOFTSERIAL1

feature -RX_PARALLEL_PWM
feature TELEMETRY
feature GPS
feature RX_SERIAL
feature SOFTSERIAL
set serial_port_1_scenario = 2
set serial_port_2_scenario = 3
set serial_port_3_scenario = 1
set msp_baudrate = 19200
set cli_baudrate = 19200
set gps_passthrough_baudrate = 19200
save

FrSky telemetry

FrSky telemetry signals are inverted. To connect a cleanflight capable board to an FrSKy receiver you have some options.

1. A hardware inverter - Built in to some flight controllers.
2. Use software serial and enable frsky_inversion.
3. Use a flight controller that has software configurable hardware inversion (e.g. STM32F30x).

For 1, just connect your inverter to a usart or software serial port.

For 2 and 3 use the cli command as follows:

set frsky_inversion = 1

CLI command differences from baseflight

gps_provider / gps_type

reason: renamed for consistency

serialrx_provider / serialrx_type

reason: renamed for consistency

rssi_channel / rssi_aux_channel

reason: improved functionality

Cleanflight supports using any RX channel for rssi. Baseflight only supports AUX1 to 4.

In Cleanflight a value of 0 disables the feature, a higher value indicates the channel number to read RSSI information from.

Example, to use RSSI on AUX1 in Cleanflight set the value to 5, since 5 is the first AUX channel.