nopnop2002
178 lines
6.1 KiB
Markdown
178 lines
6.1 KiB
Markdown
# esp-idf-can2http
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CANbus to http bridge using esp32.
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It's purpose is to be a bridge between a CAN-Bus and a HTTP-Server.
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You can visualize CAN-Frame using a visualization library such as Matplotlib.
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I inspired from [here](https://github.com/c3re/can2mqtt).
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# Software requirement
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esp-idf v4.2-dev-2243 or later.
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Use twai(Two-Wire Automotive Interface) driver instead of can driver.
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# Hardware requirements
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1. SN65HVD23x CAN-BUS Transceiver
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|SN65HVD23x||ESP32|ESP32-S2||
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|:-:|:-:|:-:|:-:|:-:|
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|D(CTX)|--|GPIO21|GPIO20|(*1)|
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|GND|--|GND|GND||
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|Vcc|--|3.3V|3.3V||
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|R(CRX)|--|GPIO22|GPIO21|(*1)|
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|Vref|--|N/C|N/C||
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|CANL|--|||To CAN Bus|
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|CANH|--|||To CAN Bus|
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|RS|--|GND|GND|(*2)|
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(*1) You can change using menuconfig.
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(*2) N/C for SN65HVD232
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2. Termination resistance
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I used 150 ohms.
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# Test Circuit
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```
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+-----------+ +-----------+ +-----------+
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| Atmega328 | | Atmega328 | | ESP32 |
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| | | | | |
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| Transmit | | Receive | | 21 22 |
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+-----------+ +-----------+ +-----------+
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| | | | | |
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+-----------+ +-----------+ | |
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| | | | | |
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| MCP2515 | | MCP2515 | | |
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+-----------+ +-----------+ | |
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+-----------+ +-----------+ +-----------+
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| | | | | D R |
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| MCP2551 | | MCP2551 | | VP230 |
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| H L | | H L | | H L |
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+-----------+ +-----------+ +-----------+
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| | | | | |
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+--^^^--+ | | +--^^^--+
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| R1 | | | | R2 |
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|---+-------|-----+-------|-----+-------|---| BackBorn H
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|-----------+-------------+-------------+---| BackBorn L
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+--^^^--+:Terminaror register
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R1:120 ohms
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R2:150 ohms(Not working at 120 ohms)
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```
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__NOTE__
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3V CAN Trasnceviers like VP230 are fully interoperable with 5V CAN trasnceviers like MCP2551.
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Check [here](http://www.ti.com/lit/an/slla337/slla337.pdf).
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# Installation for ESP32
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```
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git clone https://github.com/nopnop2002/esp-idf-can2http
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cd esp-idf-can2http
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idf.py set-target esp32
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idf.py menuconfig
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idf.py flash
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```
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# Installation for ESP32-S2
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```
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git clone https://github.com/nopnop2002/esp-idf-can2http
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cd esp-idf-can2http
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idf.py set-target esp32s2
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idf.py menuconfig
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idf.py flash
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```
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# Configuration
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## CAN Setting
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## WiFi Setting
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## HTTP Server Setting
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# Definition from CANbus to HTTP
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When CANbus data is received, it is sent by HTTP POST according to csv/can2http.csv.
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The file can2http.csv has three columns.
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In the first column you need to specify the CAN Frame type.
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The CAN frame type is either S(Standard frame) or E(Extended frame).
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In the second column you have to specify the CAN-ID as a __hexdecimal number__.
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In the last column you have to specify the HTTP-POST-Path.
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Each CAN-ID and each HTTP-POST-Path is allowed to appear only once in the whole file.
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```
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S,101,/post
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E,101,/post
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S,103,/post
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E,103,/post
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```
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When a Standard CAN frame with ID 0x101 is received, POST with the "/post" PATH.
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When a Extended CAN frame with ID 0x101 is received, POST with the "/post" PATH.
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# HTTP Server Using Tornado
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```
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sudo apt install python3-pip python3-setuptools
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python -m pip install -U pip
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python -m pip install -U wheel
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python -m pip install tornado
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cd tornado
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python can.py
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```
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# HTTP Server Using Flask
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```
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sudo apt install python3-pip python3-setuptools
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python -m pip install -U pip
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python -m pip install -U wheel
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python -m pip install -U Werkzeug
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python -m pip install flask
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cd flask
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python can.py
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```
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# Brows data Using Tornado/Flask
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Open your browser and put the Server's IP in the address bar.
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# Troubleshooting
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There is a module of SN65HVD230 like this.
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There is a __120 ohms__ terminating resistor on the left side.
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I have removed the terminating resistor.
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And I used a external resistance of __150 ohms__.
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A transmission fail is fixed.
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If the transmission fails, these are the possible causes.
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- There is no receiving app on CanBus.
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- The speed does not match the receiver.
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- There is no terminating resistor on the CanBus.
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- There are three terminating resistors on the CanBus.
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- The resistance value of the terminating resistor is incorrect.
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- Stub length in CAN bus is too long. See [here](https://e2e.ti.com/support/interface-group/interface/f/interface-forum/378932/iso1050-can-bus-stub-length).
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# Reference
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https://github.com/nopnop2002/esp-idf-can2mqtt
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