Unifire CAN Bus Cape for Raspberry Pi

Communication Hat with 2x CAN, RS232, I2C and relays.

Technical Overview
The Unifire CAN Cape adds serial networking options to your Raspberry Pi utilizing the GPIO.
The two onboard CAN Bus ports utilize the Microchip MCP2515 CAN controller, accessible per SPI interface, in combination with the Microchip MCP2551 CAN transceiver. 120Ω termination is available by jumper or control over GPIO.
The RS232 port is controlled via the RPi’s UART using the MAX3232 line-driver and receiver.
The I2C is buffered by LTC4313 and the two onboard photoMOS relays allow for simple digital control of external equipment. The IO expander for the I2C bus allows for even further expansions.
Onboard is also a DC/DC transformer allowing the CAN cape to supply the RPi with power. PoCAN (Power over CAN) makes this possible.

The CAN cape is also equipped with six blue LED indicators.

Features

The Unifire CAN Cape adds serial networking options to your Raspberry Pi 2B/3B/3B+ and other units with compatible GPIO specifications.
• Raspberry Pi connectivity, compatible with Raspberry 2B/3B/3B+
• CAN function, two onboard CAN controllers MCP2515 via SPI interface,
with transceivers MCP2551
• RS232 function, controlled via UART, half-duplex communication, line
driver and receiver MAX3232
• Buffered I2C allows for high speed communication
• 8 bit I/O expander for I2C – PCF8574
• 2 photoMOS relays, allows digital control of external equipment

Specifications
• Operating voltage: 8 - 40VDC (PoCAN) or 5V (from RPi)
• 2x CAN controller: MCP2515
• 2x CAN transceiver: MCP2551
• 232 line driver and receiver: MAX2323
• Buffered I2C
• 8 bit I/O expander for I2C – PCF8574
• DC/DC step down voltage regulator, LM2676
• Dimensions: 65mm x 56mm
• Mounting hole size: 2,54mm

Implementation in the Unifire System
The CAN cape is the centerpiece and the physical interface that connects the TARGA™ to the RPi. RS232 is used for programming the boot sector of the TARGA, I2C is used for direct hardware control (full duplex). One CAN interface is used to allow the RPi to take part in the CAN universe – as an active part (slave(s)) and/or as a passive listener (CANmon).

The relays are used to control the USB router and thus allows for remote programming of the TARGA. The IO expander allows for supervision of the different power circuits on the TARGA, thus allowing for remote supervision of internal circuits at all times.