Introduction

Here is an in-depth comprehension of the Warthog's LED Boards. This page mainly focuses on the master iteration of the boards, as the slave is nothing but a shell incorporating only the LED control current sinks.

Photo Reference

View of the chip side of the boards and port side.

Official Warthog Reference

See the LED board's wiring configuration here, and below is a referenced photo of the MCU PCB.

PCB Details

An in-depth analysis of the physical characteristics of the PCB.

Port Details

An overview of each connection's use and interaction with the PCB.

Sevcon

The Sevcon only interacts with the K1 relays to complete its 48V loop. The CAN Bus data lines never impact the operation of the boards in any way.

Main

Loops back to the MCU to communicate the state of the connected security devices.

I²C/CAN

Linked to the embedded boards, this connection provides the differential I²C to be converted, as well as the CAN Bus data lines, which don't interact with any components as they are simply diverted to the Sevcon port.

Pump / E-Stop

These two ports each serve as an enable line to the Main connector when they are respectively enabled. As the pump activates, the 24V signal is read by the MCU, and when the E-Stop loop is opened by a user, the MCU can detect the change to cut the enable motor line to the K1 relay.

Rear

Links to the slave PCB on the back end of the robot to communicate its RGB state on three independent data lines, in addition to providing power and ground reference.

48V / GND

Power supply and earth reference.

Chip Details

The Clearpath LED boards' main chips and their datasheets are provided here:

• PCA9685
• PCA9615
• MPU9250
• G5LE-1-VDDC12

Following are the details of each of the main chips' roles on the PCB.

G5LE-1-VDDC12

As seen in the PCB schematics here, this relay is necessary to complete the loop for the 48V supply to the Sevcon motor controller. Its enable pin is controlled by the motor's input signal linked to the Clearpath custom MCU-PCB, seen in the Warthog's official documentation here. Without this motor-enable 12V signal, the Sevcon's 48V CAN Bus isn't active, preventing the robot from moving.

PCA9615

The PCA9615 is widely used in differential I²C communication for its two-way conversion application. See below for the usual configuration. As seen in the detailed view of the PCB, the configuration used is of a receiver to convert the differential signal received from the MCU PCB.

PCA9685

The PCA9685 is a 16-channel I²C-addressed PWM controller. It serves here to control the intensity of each RGB component of the LED board on the front and rear of each side of the Warthog.

MPU9250

The MPU9250 is a 9-axis accelerometer. Its use isn't clear, but the leading theory is that it serves as a transform publisher for the swiveling of each side of the Warthog.

Logic Details

LED control

As seen in the PCB schematics here, the PWM controller can be controlled via differential I²C. It controls the MOSFETs' current sinks linked to each RGB component of every LED. This setup allows full control over the brightness and color for the front and back sides.

E-stop

When the E-stop chain is broken the direct power to the sevcon unit is cut but to ensure proper Can-bus shutdown a second logic layer is implemented via the G5LE-1-VDDC12 relay. When the E-stop loop is broken the 12 motor enable signal is cut via the mcu which in turn will power of the Can-bus' 48v power supply and start the blinking lights.