esp-idf-candump

Example code for CAN receive using ESP-IDF.

The ESP32 intregates a CAN controller which is compatible with the NXP SJA1000 CAN controller.
Thus, it is CAN 2.0B specification compliant and supports two message formats:

• Base frame format (11-bit ID)
• Extended frame format (29-bit ID)

ESP-IDF contains three example for TWAI, but you need two ESP32s running master and slave, or master and listen_only at the same time.
So, I made a reception-only tool with Raspberry or Arduino as the sender.

Software requirement

ESP-IDF V5.0 or later.
ESP-IDF V4.4 release branch reached EOL in July 2024.
ESP-IDF V5.1 is required when using ESP32-C6.

Hardware requirements

• SN65HVD23x CAN-BUS Transceiver
  SN65HVD23x series has 230/231/232.
  They differ in standby/sleep mode functionality.
  Other features are the same.

• Termination resistance
  I used 150 ohms.

Wireing

SN65HVD23x		ESP32	ESP32-S2/S3	ESP32-C3/C6
D(CTX)	--	GPIO21	GPIO17	GPIO0	(*1)
GND	--	GND	GND	GND
Vcc	--	3.3V	3.3V	3.3V
R(CRX)	--	GPIO22	GPIO18	GPIO1	(*1)
Vref	--	N/C	N/C	N/C
CANL	--				To CAN Bus
CANH	--				To CAN Bus
RS	--	GND	GND	GND	(*2)

(*1) You can change using menuconfig. But it may not work with other GPIOs.

(*2) N/C for SN65HVD232

Test Circuit

   +-----------+   +-----------+   +-----------+ 
   | Atmega328 |   | Atmega328 |   |   ESP32   | 
   |           |   |           |   |           | 
   | Transmit  |   | Receive   |   | 21    22  | 
   +-----------+   +-----------+   +-----------+ 
     |       |       |       |       |       |   
   +-----------+   +-----------+     |       |   
   |           |   |           |     |       |   
   |  MCP2515  |   |  MCP2515  |     |       |   
   |           |   |           |     |       |   
   +-----------+   +-----------+     |       |   
     |       |       |       |       |       |   
   +-----------+   +-----------+   +-----------+ 
   |           |   |           |   | D       R | 
   |  MCP2551  |   |  MCP2551  |   |   VP230   | 
   | H      L  |   | H      L  |   | H       L | 
   +-----------+   +-----------+   +-----------+ 
     |       |       |       |       |       |   
     +--^^^--+       |       |       +--^^^--+
     |   R1  |       |       |       |   R2  |   
 |---+-------|-------+-------|-------+-------|---| BackBorn H
             |               |               |
             |               |               |
             |               |               |
 |-----------+---------------+---------------+---| BackBorn L

      +--^^^--+:Terminaror register
      R1:120 ohms
      R2:150 ohms(Not working at 120 ohms)

NOTE
3V CAN Trasnceviers like VP230 are fully interoperable with 5V CAN trasnceviers like MCP2551.
Check here.

Installation

git clone https://github.com/nopnop2002/esp-idf-candump
cd esp-idf-candump/stdout
idf.py set-target {esp32/esp32s2/esp32s3/esp32c3/esp32c6}
idf.py menuconfig
idf.py flash

Configuration

You have to set this config value with menuconfig.

• CAN Bitrate
• CTX GPIO number
• CRX GPIO number

ScreenShot

Acceptance Filter

The explanation about the acceptance filter is available here.
There are diagrams of Bit layout of single filter mode and Bit layout of dual filter mode, but they are described in Right side MSBit.
I've never seen a Right side MSBit before, so I thought it was a Left side MSBit.
I was very confused.

Reference

https://github.com/nopnop2002/esp-idf-can2http

https://github.com/nopnop2002/esp-idf-can2mqtt

https://github.com/nopnop2002/esp-idf-can2usb

https://github.com/nopnop2002/esp-idf-can2websocket

https://github.com/nopnop2002/esp-idf-can2socket

https://github.com/nopnop2002/esp-idf-CANBus-Monitor