Adafruit CAN Bus BFF Add-On for QT Py

The QT Py boards are perfect for compact microcontroller projects that deliver impressive performance. Now, with our new Adafruit CAN Bus BFF Add-On, you can transform multiple QT Py boards into highly efficient and compact CAN bus devices.

This small-scale networking standard, known as CAN Bus, was initially designed for use in cars and buses. However, it is now utilized in various robotics and sensor networks that require improved range and addressing capabilities compared to I2C. Due to its 2-wire differential setup, CAN is suitable for noisy environments and long-distance communication, making it a valuable tool for devices without the capabilities to communicate through Ethernet.

The CAN Bus BFF Add-On for QT Py allows for quick and simple attachment of new nodes to the shared network. With a set frequency and address for each node, messages are sent at a consistent 1Mbps rate, ensuring efficient communication. Additionally, the clever data encoding allows for detection of message collisions and retransmission at a later time. All nodes have the ability to listen in on messages specifically for them, creating a seamless and effective network. 

The Adafruit CAN Bus BFF Add-On for QT Py allows for easy connection to a CAN Bus, compatible with all boards and utilizing a straightforward SPI interface. This add-on utilizes the MCP26525 - also referred to as the MCP2515 controller and MCP2551 transceiver - a widely-used and supported chipset with drivers available in both Arduino and CircuitPython. It only requires an SPI port and 1 chip-select pin, plus an optional IRQ pin, and can handle message transmission and reception in standard or extended format at speeds up to 1 Mbps.

We've added a few nice extras to this BFF to make it useful in many common CAN scenarios:

• JST PH socket - Plug in one of our JST PH 3-pn cables (not included!) for fast wiring and connection/disconnection. Black wire is ground, Red wire is CAN H, White wire is CAN L.
• 120 ohm termination resistor on board, you can remove the termination easily by cutting the jumper on the top of the board.
• Pre-connected CS pin to A3. There's also jumpers if you want to connect the IRQ, Reset and Silent pins.

We include some header that you can solder to your QT Py. You can also pick up an Itsy Bitsy short female header kit to make it removable but compact, you'll just need to trim down the headers to 7 pins long. Works with any QT Py or Xiao-shaped board that has the SPI port and A3 pin available.

QT Py and JST PH 3-Pin cable is not included.