ArduPilot Instructions

Guide for setting up an ARK CANnode as a PWM servo expander with ArduPilot AP_Periph firmware, including gripper/dropper configuration.

The ARK CANnode can run ArduPilot AP_Periph firmware, enabling it to act as a DroneCAN peripheral node for expanding servo outputs, ESC control, and sensor connectivity over CAN.

Flashing Firmware

Flight Controller

Flash your ARK flight controller with ArduPilot firmware using QGroundControl over USB.

Enable CAN on the Flight Controller

Set the following parameters on the flight controller and reboot:

Parameter	Value	Description
CAN_P1_DRIVER	1	Enable first CAN driver
CAN_D1_PROTOCOL	1	Set protocol to DroneCAN

CANnode

Flash the ARK CANnode with AP_Periph firmware using the DroneCAN GUI Tool. See the DroneCAN GUI Tool Guide for detailed instructions on connecting and uploading firmware.

1. Download the latest AP_Periph firmware for the ARK CANnode from firmware.ardupilot.org/AP_Periph

2. Connect the CANnode to the flight controller's CAN bus

3. Open the DroneCAN GUI Tool

4. Double-click the CANnode in the node list

5. Click Update Firmware and select the .bin AP_Periph firmware file

Gripper/Dropper Setup

This example configures the first CANnode PWM output as a servo gripper for a dropping mechanism.

Flight Controller Parameters

Parameter	Value	Description
CAN_D1_UC_SRV_BM	1	Enable Servo Channel 1 over CAN (bitmask bit 0)
SERVO1_FUNCTION	28	Gripper
GRIP_ENABLE	1	Enable gripper
GRIP_TYPE	0	Servo
GRIP_GRAB	1000	PWM value for grab/close (adjust to your servo)
GRIP_RELEASE	1200	PWM value for release/open (adjust to your servo)
BRD_SAFETY_MASK	1	Allow Servo Channel 1 to output with safety on

After setting GRIP_ENABLE = 1, a reboot is required before the other GRIP_* parameters will appear.

CAN_D1_UC_SRV_BM defaults to 0, meaning no servo commands are sent over CAN. This is the most commonly missed parameter.

CANnode Parameters

The defaults should work without changes. The CANnode output functions map to flight controller servo channels by default (OUT1 maps to FC Servo 1, OUT2 to Servo 2, etc.).

The OUT* parameters are accessed through the DroneCAN parameter interface. In the DroneCAN GUI Tool, double-click the CANnode and click Fetch All to view them.

Triggering the Gripper

Via RC

Assign a switch on your transmitter to control the gripper:

Parameter	Value	Description
RCx_OPTION	19	Gripper Release

Replace x with the RC channel number mapped to your desired switch.

Via MAVLink

The gripper can also be controlled programmatically using MAV_CMD_DO_GRIPPER. The following Python script sends gripper open/close commands over USB:

2KB

gripper_cmd.py

Open

Usage:

python3 gripper_cmd.py open
python3 gripper_cmd.py close

The script auto-detects ARK flight controllers connected via USB. Use --port to specify a device manually:

python3 gripper_cmd.py open --port /dev/ttyACM0

Using Multiple Servos

To use the first 3 CANnode outputs, set CAN_D1_UC_SRV_BM = 7 (bits 0, 1, 2) and configure SERVO1_FUNCTION, SERVO2_FUNCTION, and SERVO3_FUNCTION on the flight controller. Update BRD_SAFETY_MASK accordingly (e.g., 7 for channels 1-3).

Building Firmware

Application

./waf configure --board ARK_CANNODE
./waf AP_Periph

Bootloader

./waf configure --board ARK_CANNODE --bootloader
./waf bootloader

The bootloader can also be updated from the running AP_Periph firmware by setting FLASH_BOOTLOADER = 1 on the CANnode via the DroneCAN GUI Tool.

The hardware definition can be found here: https://github.com/ArduPilot/ardupilot/tree/master/libraries/AP_HAL_ChibiOS/hwdef/ARK_CANNODE