CAN FD Hat (40-Pin)

Table of Contents

CAN FD Hat (40-Pin)

1 Overview

1.1 Bill of Materials (BOM)

Manufacturer Part Number	Manufacturer	Description	Quantity
MCP2518FDT-E/QBB	Microchip Technology	CAN FD to SPI Controller	1
TJA1057BTK	NXP USA Inc.	CAN Bus Transceiver	1
JS202011JAQN	C&K	DPDT Slide Switch Right Angle	1
ECS-400-10-37B2-CKY-TR	ECS Inc.	40 MHz crystal	1

2 Board Specifications

2.1 Connectors

Connectors fixed by hardware (PCB traces or the connector itself).

Connector	Ref	Description
`40-pin`	J1	Standard 40-pin (2x20) GPIO pin header
`CAN`	J2	Pin 1: ground, Pin 2: CAN high, Pin 3: CAN low

2.2 Switches & Jumpers

User controllable hardware and/or firmware driven inputs.

Switch/Jumper	Ref	Description
`CAN termination`	SW1	1 + 2 = 120 Ohm termination, 2 + 3 = No termination
`CAN silent`	JP1	Open = normal operation, closed = silent mode

2.3 Linux (Ubuntu) Setup

This setup is for Raspberry Pis running Ubuntu and similar Debian distros.

Install MCP251XFD required drivers (example showing can-utils).
```
sudo apt update
sudo apt install -y can-utils
```

Enable SPI and add the MCP2518FD overlay.

sudo nano /boot/firmware/config.txt

# Add the following lines to config.txt:
dtparam=spi=on
dtoverlay=mcp251xfd,spi0-0,oscillator=40000000,interrupt=22,spimaxfrequency=10000000

Reboot the system.
```
sudo reboot
```

Run CAN.

For CAN classic setup (example for 500 kbps, 87.5% sample point, bus error reporting):

sudo ip link set can0 down 2>/dev/null || true
sudo ip link set can0 type can bitrate 500000 sample-point 0.875 berr-reporting on
sudo ip link set can0 up

For CAN FD setup (example for 1 Mbps nominal rate, 80% sample point, 4 Mbps data phase rate, bus error reporting):

sudo ip link set can0 down
sudo ip link set can0 type can bitrate 1000000 sample-point 0.80 dbitrate 4000000 dsample-point 0.80 fd on berr-reporting on
sudo ip link set can0 up

3 Schematics

Download PDF: can_hat_40_pcb-schematic.pdf.

4 CAD 3D Model

Download PDF: can_hat_40_pcb-3D.step.