open-LIN/open-LIN-c implementation in ESP32.

This project implements hardware abstraction APIs of open-LIN-c in ESP32 based on CW-B-W/ESP32-SoftwareLIN.

Besides of the implementation, there are simple examples to illustrate how to use open-LIN-c.

• Send / Receive LIN bus frames on both LIN master and LIN slave
• Autobaud detection is supported by LIN slave

1. Use VS Code with extension PlatformIO to open the project folder
2. Build and upload the ESP32 firmware with PlatformIO
   • If this device is acting as a LIN master, copy the examples/master.cpp to src/
   • If this device is acting as a LIN slave, copy the examples/slave.cpp to src/
3. Connect the UART pins of the ESP32 LIN master and ESP32 LIN slave

In examples/master.cpp, master_frame_table is used to store the periodic frames information. open-LIN-c keeps iterating through the table and send each frame itme.
Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/master.cpp#L44-L47

In examples/master.cpp, frame_slot is used to store the periodic frames information.
When a framed is received, open-LIN-c searches the received frame PID in the frame_slot and return the frame information if found.
Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/slave.cpp#L54-L57

In examples/master.cpp, function open_lin_master_dl_rx_callback is used to handle the frames received. Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/master.cpp#L84-L91

In examples/master.cpp, function open_lin_error_handler is used to handle the errors. Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/master.cpp#L93-L153

In examples/slave.cpp, function open_lin_on_rx_frame is used to handle the frames received. Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/slave.cpp#L115-L122

In examples/slave.cpp, function open_lin_error_handler is used to handle the errors. Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/slave.cpp#L124-L185

In examples/slave.cpp, if LIN_AUTOBAUD is defined, autobaud is enabled, otherwise autobaud is disabled. Refer to https://github.com/CW-B-W/ESP32-openLIN/blob/677470aaf2609fb12ef86f3ba0c760aa747735f0/examples/slave.cpp#L35

This project was tested with Microchip LIN Serial Analyzer and NXP TJA1021 module.
(Sleep was not used in this test)

1. Use examples/master.cpp to do this test.
2. Open LIN Serial Analyzer Debug Tool
3. Hold ESP32 reset button (Don't release now)
4. Connect Debug Tool with LIN Serial Analyzer
5. Choose to use Enhanced Checksum Type in Debug Tool
6. Setup Slave Response in Debug Tool
7. Select the responses and click Add Slave Response Buffer
8. Release ESP32 reset button
9. LIN frames should be detected and shown on the screen

Compared with the result in logic analyzer

1. Use examples/slave.cpp to do this test.
2. Open LIN Serial Analyzer Debug Tool
3. Connect Debug Tool with LIN Serial Analyzer
4. Choose to use Enhanced Checksum Type in Debug Tool
5. Setup Master frames in Debug Tool
6. Select the two frames and click Send Continuous
7. LIN frames should be detected and shown on the screen

Compared with the result in logic analyzer

This project was also tested with VN1611.
We can take advantages of Vector XL Driver Library to test it with VN1611.