ArduPilot
PWM 5V tolerant I/O	S1	PWM1 GPIO50	TIM8_CH4	DMA/DShot	Group1
	S2	PWM2 GPIO51	TIM8_CH3	DMA/DShot
	S3	PWM3 GPIO52	TIM1_CH3N	DMA/DShot	Group2
	S4	PWM4 GPIO53	TIM1_CH1	DMA/DShot
	S5	PWM5 GPIO54	TIM2_CH4	DMA/DShot	Gourp3
	S6	PWM6 GPIO55	TIM2_CH3	DMA/DShot
	S7	PWM7 GPIO56	TIM2_CH2	DMA/DShot
	S8	PWM8 GPIO57	TIM2_CH1	DMA/DShot
	S9	PWM9 GPIO58	TIM12_CH1	NO DMA	Gourp4
	S10	PWM10 GPIO59	TIM13_CH1	NO DMA	Gourp5
	–	–	–	–	–
	LED pad	PWM12 GPIO61	TIM3_CH4	DMA/DShot	Gourp7
		SERVO12_FUNCTION 120,   NTF_LED_TYPES  neopixel
Mixing Dshot and normal PWM operation for outputs is restricted into groups, ie. enabling Dshot for an output in a group requires that ALL outputs in that group be configured and used as Dshot, rather than PWM outputs. If servo and motor are mixed in same group, make sure this group run lowest PWM frequency according to the servo specification. ie. Servo supports Max. 50Hz, ESC must run at 50Hz in this group.
ADC	Vbat Pad	1K:20K divider builtin 0~60V	on board battery voltage	BATT_VOLT_PIN BATT_VOLT_MULT	14 21.0
	Curr pad	0~3.3V	on board  current sensor	BATT_CURR_PIN BATT_AMP_PERVLT	15 66.7
	RSSI Pad	0~3.3V	RSSI ADC,  Analog RSSI	RSSI_ANA_PIN RSSI_TYPE	8 2
	ADC	0~3.3V	AirS ADC,  Analog Airspeed	ARSPD_PIN ARSPD_TYPE	10 2
I2C	I2C1	5V tolerant I/O	Compass	COMPASS_AUTODEC	1
			onboard Baro SPL06-001	Address	0x76
			Digital Airspeed I2C MS4525 DLVR-L10D	ARSPD_BUS ARSPD_TYPE ARSPD_TYPE	1 1 9
UART 5V tolerant I/O	USB	USB		console	SERIAL0
	TX1 RX1	USART1	with DMA	telem1	SERIAL1
	TX3 RX3	USART3	NO DMA	telem2	SERIAL2
	TX5 RX5	UART5	NO DMA	GPS1	SERIAL3
	TX4 RX4	UART4	NO DMA	USER	SERIAL4
	TX6 RX6	USART6	TX6 with DMA	USER	SERIAL5
	TX2 RX2 SBUS	USART2	with DMA	RC input/Receiver	SERIAL6
		RX2	IBUS/DSM/PPM	BRD_ALT_CONFIG 0 Default
		Sbs pad	SBUS
		TX2 & RX2	CRSF	BRD_ALT_CONFIG 1 SERIAL6_PROTOCOL 23	SERIAL6_OPTIONS 0
		TX2	uninverted FPort (hacked)		SERIAL6_OPTIONS 4
		TX2	SRXL2		SERIAL6_OPTIONS 4

• “Internal errors 0x4000 l:213 spi_fail” warining,  pls set LOG_BACKEND_TYPE = 1 (File) for SD card logging.
• If sending highspeed serial data (eg. 921600 baud) to the board, use USART1(Serial1) or USART2(Serial6).

Frsky Smartport Telemetry

• non-inverted (hacked) S.Port signal

• any spare Uart_TX
• SERIALx_BAUD   57
• SERIALx_OPTIONS  7
• SERIALx_PROTOCOL  4  or 10(for yaapu)

DJI FPV OSD (ArduPilot 4.1)

https://ardupilot.org/plane/docs/common-msp-osd-overview.html

• OSD_TYPE = 3
• SERIAL4_PROTOCOL = 33
• MSP_OPTIONS = 0 (polling mode)

Relay(PINIO)

• PINIO1,  PIO1 pad, Low Level by default
• PINIO2,  Camera switch, C1 ON by default

# GPIOs

• PA4  PINIO1  OUTPUT  GPIO(81)  LOW  //PIO1 pad
• PB5  PINIO2  OUTPUT  GPIO(82)  LOW  //camera switch

# RCx_OPTION: RC input option

• 28   Relay On/Off
• 34   Relay2 On/Off
• 35   Relay3 On/Off
• 36   Relay4 On/Off

e.g.

• RELAY_PIN       81    //PIO1 GPIO
• RC7_OPTION   28    //Relay On/Off, Use CH7 of Transmitter to control PIO1 Low/High Level
• RELAY_PIN2     82    //Camera switch GPIO
• RC8_OPTION   34    //Relay2 On/Off, Use CH8 of Transmitter to control high/low level on PB5 pad

The configured feature will be triggered when the auxiliary switch’s pwm value becomes higher than 1800. It will be deactivated when the value falls below 1200.

Check the pwm value sent from the transmitter when the switch is high and low using the Mission Planner’s Initial Setup >> Mandatory Hardware >> Radio Calibration screen. If it does not climb higher than 1800 or lower than 1200, it is best to adjust the servo end points in the transmitter.