Atlas Control

Configuration

This section covers the controller-specific details worth knowing when setting up ArduPilot.

Serial ports

Default port order. Protocols are freely configurable — any port can be reassigned to the peripheral you need.

SERIAL	Port	Default use	DMA
SERIAL0	USB (OTG1)	Console, MAVLink2	—
SERIAL1	USART2	TELEM1, MAVLink2	yes, CTS/RTS
SERIAL2	USART6	TELEM2, MAVLink2	yes, CTS/RTS
SERIAL3	USART1	GPS1	—
SERIAL4	UART4	GPS2	—
SERIAL5	UART8	RC IN on the servo rail	yes
SERIAL6	UART7	DEBUG, system console	—
SERIAL7	USART3	TELEM3, MAVLink2	yes
SERIAL8	USB (OTG2)	SLCAN	—

PWM outputs

The controller has 14 PWM outputs. All support standard PWM; channels 1–12 additionally support DShot.

Group	Outputs	Timer	Protocols
Group 1	1, 2, 3, 4	TIM5	PWM, DShot
Group 2	5, 6, 7, 8	TIM4	PWM, DShot
Group 3	9, 10, 11, 12	TIM1	PWM, DShot
Group 4	13, 14	TIM12	PWM only, no DMA

Important

All outputs in a group must run at the same rate and protocol. If any channel in a group uses DShot, every channel in that group must use DShot too.

GPIO

Any of the 14 outputs can be used as a GPIO — for relays, buttons, RPM measurement and so on. Set SERVOx_FUNCTION = -1 to do so.

// ArduPilot GPIO numbering
PWM1(M1)=50   PWM2(M2)=51   PWM3(M3)=52   PWM4(M4)=53
PWM5(M5)=54   PWM6(M6)=55   PWM7(M7)=56   PWM8(M8)=57
PWM9(M9)=58   PWM10(M10)=59 PWM11(M11)=60 PWM12(M12)=61
PWM13(M13)=62 PWM14(M14)=63 RSSI=92

Analog inputs

The number is the firmware's ADC channel, which you put into the pin parameter of the relevant device. It is not a connector contact or an MCU package pin.

Input	Connector	Parameter	Value	Range
Battery voltage	POWER A	`BATT_VOLT_PIN`	16	up to 3.3 V
Battery current	POWER A	`BATT_CURR_PIN`	17	up to 3.3 V
RSSI	RSSI	`RSSI_ANA_PIN`	6	up to 3.3 V

RC input

The RC IN contact on the servo rail supports all unidirectional ArduPilot protocols: SBUS, CPPM, DSM. The same contact is the SERIAL5 (UART8) port, which is what protocols requiring a UART use.

For CRSF, ELRS, FPort and SRXL2 set:

// FPort
SERIAL5_PROTOCOL = 23
SERIAL5_OPTIONS  = 15

// CRSF / ELRS
SERIAL5_PROTOCOL = 23
SERIAL5_OPTIONS  = 0

// SRXL2 — connect the receiver TX pin only
SERIAL5_PROTOCOL = 23
SERIAL5_OPTIONS  = 4

Battery monitoring

DroneCAN — the default

A DroneCAN power module connects to the POWER C port or to CAN1.

BATT_MONITOR  = 8
CAN_P1_DRIVER = 1

Analog module

An analog module connects to the POWER A port.

BATT_MONITOR    = 4
BATT_VOLT_PIN   = 16
BATT_CURR_PIN   = 17
BATT_VOLT_MULT  = 18.0
BATT_AMP_PERVLT = 24.0
BATT_VLT_OFFSET = -0.1

Second monitor

For a second battery use the BATT2_ parameter set.

Compass

The board has an internal RM3100 compass. The controller normally sits inside the airframe, where the magnetic field is distorted by currents in the power wiring, so the external compass in the GPS module is usually the better choice as primary. External compasses connect to any of the I2C ports.

IMU heater

The controller has a built-in heater for the inertial sensors that holds them at a constant temperature and so reduces drift. The target temperature is set by BRD_HEAT_TARG, 45 °C by default.