Awesome
esp-idf-can2websocket
Brows CAN-Frame using esp-idf.
You can browse the CAN-Frame in real time using the built-in WebSocket server.
Similar to this, but this project uses the WebSocket protocol instead of the HTTP protocol.
ESP32 acts as a WebSocket server.
I used this component.
This component can communicate directly with the browser.
There is an example of using the component here.
It's a great job.
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-can2websocket
cd esp-idf-can2websocket
git clone https://github.com/Molorius/esp32-websocket components/websocket
idf.py set-target {esp32/esp32s2/esp32s3/esp32c3/esp32c6}
idf.py menuconfig
idf.py flash
Configuration
CAN Setting
Display all received frames to STDOUT.
WiFi Setting
You can use Static IP.
You can connect using mDNS name.
Definition CANbus Frame
When CANbus data is received, it is sent by built-in HTTP server according to csv/can2http.csv.
The file can2http.csv has three columns.
In the first column you need to specify the CAN Frame type.
The CAN frame type is either S(Standard frame) or E(Extended frame).
In the second column you have to specify the CAN-ID as a hexdecimal number.
In the last column you have to specify the Frame Name.
A descriptive name for CAN Frame.
S,101,Water Temperature
E,101,Water Pressure
S,103,Gas Temperature
E,103,Gas Pressure
Format conversion
-
Binary
-
Octal
-
Decimal
-
Hexadecimal
Troubleshooting
There is a module of SN65HVD230 like this.
There is a 120 ohms terminating resistor on the left side.
I have removed the terminating resistor.
And I used a external resistance of 150 ohms.
A transmission fail is fixed.
If the transmission fails, these are the possible causes.
- There is no receiving app on CanBus.
- The speed does not match the receiver.
- There is no terminating resistor on the CanBus.
- There are three terminating resistors on the CanBus.
- The resistance value of the terminating resistor is incorrect.
- Stub length in CAN bus is too long. See here.
WEB Page
The WEB page is stored in the html folder.
You can change it as you like.
Task Structure Diagram
Reference
https://github.com/nopnop2002/esp-idf-candump
https://github.com/nopnop2002/esp-idf-can2http
https://github.com/nopnop2002/esp-idf-can2mqtt
https://github.com/nopnop2002/esp-idf-can2usb