Hardware Reference

Specifications

Specification	Value
Optical flow sensor	PixArt PAW3902
Flow working range	80 mm to infinity
Low light	Tracks under super low light conditions of >9 lux. 40 mW IR LED on the board for improved low light operation
Max flow rate	7.4 rad/s
Distance sensor	Broadcom AFBR-S50LV85D time-of-flight, integrated 850 nm laser light source
Distance range	Typically up to 30 m
Field of view	12.4° × 6.2° with 32 pixels. 2° × 2° transmitter beam illuminates 1 to 3 pixels
IMU	Bosch BMI088 or InvenSense ICM-42688-P, 6-axis
MCU	STM32F412CEU6
CAN	2× Pixhawk-standard 4-pin JST-GH, software-toggleable built-in termination resistor
Debug	Pixhawk-standard 6-pin JST-SH
Power	5 V, 71 mA average, 76 mA max
Dimensions	3 × 3 × 1.4 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

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

You will see both red and blue LEDs on the ARK Flow when it is being flashed, and a solid blue LED if it is running properly.

If you see a solid red LED there is an error and you should check the following:

• Make sure the flight controller has an SD card installed.

• Make sure the Ark Flow has ark_can-flow_canbootloader installed prior to flashing ark_can-flow_default.

• Remove binaries from the root and ufw directories of the SD card and try to build and flash again.

Wiring

The ARK Flow is connected to the CAN bus using a Pixhawk standard 4 pin JST GH cable. For more information, refer to the CAN Wiring instructions.

Multiple sensors can be connected by plugging additional sensors into the ARK Flow's second CAN connector.

Mounting

The recommended mounting orientation is with the connectors on the board pointing towards back of vehicle, as shown in the following picture.

ARK Flow align with Pixhawk

3D Model and Case

File	Contents
ARK_Flow_Rev_2_3D_Model.step	Board, rev 2
ARK_Flow_Rev_2_3D_Model_With_FOV.step	Board, rev 2, with the sensor field of view
Top_Case_Rev_1.stl	Case top, rev 1
Bottom_Case_Rev_1.stl	Case bottom, rev 1

All files: ARK_Flow in ark-hardware

Schematic and BOM

File	Contents
ARK_Flow_Rev_2_Schematic.pdf	Schematic, rev 2
ARK_Flow_Rev_2_BOM.xlsx	Bill of materials, rev 2