CANBOB

The CAN Break Out Board (or CANBOB) is a module board that enables USB or SPI to CAN communication using the MCP2515. The jobset generated files (i.e. Gerbers and BOM) are in the Releases section of the repository.

For programming the on-board ATmega please see the Programming ATmega.md file and for testing it with a Raspberry Pi see the Raspi CAN Setup.md.

User Guide

CANBOB provides a single switch to switch between MCU Mode or USB Mode (See Figure 1 in the Images section below), indicated by the silkscreen near the slide switch. Use CANBOB in MCU Mode with an external microcontroller, or in USB Mode with a USB connection to a host. See instructions below for more information.

USB Mode

To use CANBOB in USB Mode make sure to slide the switch to the correct position and plug in your micro USB or USB-C cable to CANBOB and the host. See the Output Header section below for where to connect your outputs.

MCU Mode

To use CANBOB with external microcontroller, slide the switch to the MCU Mode position. Connect the appropriate pins to the input header with the pinout below,

Pin Number	Function	Description
1	CLK	SPI Clock Input
2	MOSI	SPI Main Out Sub In
3	MISO	SPI Main In Sub Out
4	CS	SPI Chip Select
5	INT	SPI Interrupt
6	5V	5V Supply
7	GND	Device Ground
8	GND	Device Ground

Facing the connector, the top row has all the odd numbered pins, with the top right pin being pin 1, and the bottom row has all the even numbered pins. See Figure 2 in the Images section below.

Output Header

The output header contains all the necessary CAN outputs like CAN H/L and CAN termination points. It is also used to breakout the remaining pins of the MCP2515 such as the Receive Buffers (RXxBUF) and the Transmit Buffers' RTS (TXxRTS) signals. The ATmega also has some pins broken out there such as 6 GPIOs or ADCs with 2 of them able to be used for I2C communication, and the UART RX/TX lines. Please see the pinout below,

Pin Number	Function	Description
1	ADC3/GPIO3	ATmega ADC/GPIO
2	ADC2/GPIO2	ATmega ADC/GPIO
3	ADC1/GPIO1	ATmega ADC/GPIO
4	ADC0/GPIO0	ATmega ADC/GPIO
5	ADC5/GPIO5/SCL	ATmega ADC/GPIO
6	ADC4/GPIO4/SDA	ATmega ADC/GPIO
7	RX1BUF	MCP2515 Receive Buffer
8	RX0BUF	MCP2515 Receive Buffer
9	TX0RTS	MCP2515 Transmit Buffer RTS
10	TX1RTS	MCP2515 Transmit Buffer RTS
11	TX2RTS	MCP2515 Transmit Buffer RTS
12	CLKOUT	MCP2515 Clock Output
13	TX	ATmega TX
14	RX	ATmega RX
15	CANH	CAN High
16	CANL	CAN Low
17	CAN-JMP	CAN Jumper for termination
18	CAN-JMP	CAN Jumper for termination
19	GND	Device Ground
20	GND	Device Ground

Facing the connector, the top row has all the odd numbered pins, with the top right pin being pin 1, and the bottom row has all the even numbered pins. See Figure 3 in the Images section below.

Images

Figure 1. Showing slide switch

Figure 2. Showing input connectors and pinout

Figure 3. Showing output connector pinout

Licenses

Hardware is located in hardware/PCB/ and is licensed under the CERN-OHL-P v2 License provided in LICENSE-CERN-OHL-P. User guide for the license is provided in cern_ohl_p_v2_howto.pdf.

Firmware located in firmware/arduino-canbus-monitor/ is licensed under the MIT License provided in LICENSE-MIT and more details regarding attribution are in firmware/README.md.

Documentation is licensed under Creative Commons Attribution 4.0 International and is provided in LICENSE-CC-BY.

Unless otherwise noted, all files in each directory are covered by the license listed above and are provided with absolutely NO WARRANTY.

Copyright (c) 2025 Mage Control Systems Ltd