> For the complete documentation index, see [llms.txt](https://docs.arkelectron.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.arkelectron.com/products/sensor/ark-cannode/hardware.md).

# Hardware Reference

![ARK CANnode](https://docs.px4.io/main/assets/ark_cannode.-X5QpRbg.jpg)

## Specifications

| Specification | Value                                                                                                     |
| ------------- | --------------------------------------------------------------------------------------------------------- |
| IMU           | [InvenSense ICM-42688-P](https://invensense.tdk.com/products/motion-tracking/6-axis/icm-42688-p/), 6-axis |
| MCU           | STM32F412CGU6, 1 MB flash                                                                                 |
| CAN           | 2× Pixhawk-standard 4-pin JST-GH                                                                          |
| I2C           | Pixhawk-standard 4-pin JST-GH                                                                             |
| UART and I2C  | Pixhawk-standard basic GPS port, 6-pin JST-GH                                                             |
| SPI           | Pixhawk-standard 7-pin JST-GH                                                                             |
| PWM           | 8 outputs on a 10-pin JST-GH, matching the Pixhawk 4 PWM connector pinout                                 |
| Debug         | Pixhawk-standard 6-pin JST-SH                                                                             |
| Power         | 5 V, current depends on connected peripherals                                                             |
| Dimensions    | 3.0 × 3.0 × 1.03 cm                                                                                       |
| Weight        | 5 g                                                                                                       |

## Pinout

### CAN (×2) — 4-pin JST-GH

| Pin | Signal | Voltage |
| --- | ------ | ------- |
| 1   | 5V     | 5.0 V   |
| 2   | CAN\_P | 5.0 V   |
| 3   | CAN\_N | 5.0 V   |
| 4   | GND    | GND     |

### UART1/I2C1 — 6-pin JST-GH

| Pin | Signal            | Voltage |
| --- | ----------------- | ------- |
| 1   | 5.0V out (500 mA) | 5.0 V   |
| 2   | USART1\_TX        | 3.3 V   |
| 3   | USART1\_RX        | 3.3 V   |
| 4   | I2C1\_SCL         | 3.3 V   |
| 5   | I2C1\_SDA         | 3.3 V   |
| 6   | GND               | GND     |

### I2C1 — 4-pin JST-GH

| Pin | Signal            | Voltage |
| --- | ----------------- | ------- |
| 1   | 5.0V out (500 mA) | 5.0 V   |
| 2   | I2C1\_SCL         | 3.3 V   |
| 3   | I2C1\_SDA         | 3.3 V   |
| 4   | GND               | GND     |

### SPI — 7-pin JST-GH

| Pin | Signal      | Voltage |
| --- | ----------- | ------- |
| 1   | 5.0V        | 5.0 V   |
| 2   | SPI2\_SCK   | 3.3 V   |
| 3   | SPI2\_MISO  | 3.3 V   |
| 4   | SPI2\_MOSI  | 3.3 V   |
| 5   | SPI2\_CS\_1 | 3.3 V   |
| 6   | SPI2\_CS\_2 | 3.3 V   |
| 7   | GND         | GND     |

### PWM — 10-pin JST-GH

| Pin | Signal                                      | Voltage |
| --- | ------------------------------------------- | ------- |
| 1   | Pulled up to 3.3V through a 1.5 kΩ resistor | 3.3 V   |
| 2   | TIM2\_CH1\_PWM1                             | 3.3 V   |
| 3   | TIM2\_CH2\_PWM2                             | 3.3 V   |
| 4   | TIM2\_CH3\_PWM3                             | 3.3 V   |
| 5   | TIM3\_CH1\_PWM4                             | 3.3 V   |
| 6   | TIM3\_CH2\_PWM5                             | 3.3 V   |
| 7   | TIM3\_CH3\_PWM6                             | 3.3 V   |
| 8   | TIM3\_CH4\_PWM7                             | 3.3 V   |
| 9   | TIM4\_CH2\_PWM8                             | 3.3 V   |
| 10  | GND                                         | GND     |

### Debug — 6-pin JST-SH

| Pin | Signal     | Voltage |
| --- | ---------- | ------- |
| 1   | 3.3V       | 3.3 V   |
| 2   | USART2\_TX | 3.3 V   |
| 3   | USART2\_RX | 3.3 V   |
| 4   | FMU\_SWDIO | 3.3 V   |
| 5   | FMU\_SWCLK | 3.3 V   |
| 6   | GND        | GND     |

## LEDs

With the PX4 DroneCAN bootloader and firmware, the RGB status LED shows:

| Status LED                          | Meaning                                                                                                                                                                                                       |
| ----------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Green, fast blink (10 Hz)           | Node firmware running. It does not change with CAN traffic.                                                                                                                                                   |
| Green, slow blink (1 Hz)            | Bootloader listening for CAN traffic                                                                                                                                                                          |
| Blue, blinking (2 Hz)               | Bootloader waiting for a node ID from the flight controller                                                                                                                                                   |
| Blue and green, blinking (3 Hz)     | Bootloader waiting up to 3 s for the flight controller to start a firmware update                                                                                                                             |
| Red, green and blue together (3 Hz) | Firmware update in progress                                                                                                                                                                                   |
| Red, blinking                       | Firmware update error. 1 Hz: the flight controller returned a file error. 2 Hz: the flight controller stopped responding. 4 Hz: the image failed its CRC check. A failed update restarts the node after 20 s. |

Without valid firmware the node stays in the bootloader until the flight controller flashes it.

If the status LED blinks red, check the following:

* Make sure the flight controller has an SD card installed.
* Make sure the ARK CANnode has `ark_cannode_canbootloader` installed prior to flashing `ark_cannode_default`.
* Remove binaries from the root and ufw directories of the SD card and try to build and flash again.

## Wiring

The ARK CANnode is connected to the CAN bus using a Pixhawk standard 4 pin JST GH cable. For more information, refer to the [CAN Wiring](https://docs.px4.io/main/en/can/#wiring) instructions.

## 3D Model and Case

| File                                                                                                                                               | Contents             |
| -------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- |
| [ARK\_CANNODE\_Rev\_1\_3D\_Model.step](https://github.com/ARK-Electronics/ark-hardware/raw/main/ARK_CANnode/model/ARK_CANNODE_Rev_1_3D_Model.step) | Board, rev 1         |
| [Top\_Case\_0.2.stl](https://github.com/ARK-Electronics/ark-hardware/raw/main/ARK_CANnode/case/Top_Case_0.2.stl)                                   | Case top, rev 0.2    |
| [Bottom\_Case\_0.1.stl](https://github.com/ARK-Electronics/ark-hardware/raw/main/ARK_CANnode/case/Bottom_Case_0.1.stl)                             | Case bottom, rev 0.1 |

All files: [ARK\_CANnode in ark-hardware](https://github.com/ARK-Electronics/ark-hardware/tree/main/ARK_CANnode)

## Schematic and BOM

| File                                                                                                                                                  | Contents                 |
| ----------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------ |
| [ARK\_CANNODE\_Rev\_1\_Schematic.pdf](https://github.com/ARK-Electronics/ark-hardware/raw/main/ARK_CANnode/schematic/ARK_CANNODE_Rev_1_Schematic.pdf) | Schematic, rev 1         |
| [ARK\_CANNODE\_Rev\_1\_BOM.xlsx](https://github.com/ARK-Electronics/ark-hardware/raw/main/ARK_CANnode/bom/ARK_CANNODE_Rev_1_BOM.xlsx)                 | Bill of materials, rev 1 |


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