I got the ESP32RET-firmware working on the (low cost) LILYGO T-CAN485 board

[floeplala]

I got the ESP32RET firmware working on the LILYGO T-CAN485 board. This is a low cost ($12) ESP32-based board with a built-in CANbus interface, so you don't need any soldering: https://lilygo.cc/products/t-can485. No changes in the firmware are needed, all you have to do is adjust some i/o-ports since the canbus (and the led) is connected on different I/O-ports

Howto:

• Go to https://github.com/collin80/ESP32RET and click on the green 'Code'-button and choose 'Download ZIP' in the submenu
• Extract the downloaded zip-file, rename it from 'ESP32RET-master' to 'ESP32RET' and place it in your Arduino folder.
• Open the file config.h and edit these two lines:

   69  #define A0_LED_PIN 2   --> define A0_LED_PIN 4   // io-port for the led on the t-can485
   73  #define BRIGHTNESS 190 --> #define BRIGHTNESS 20 // the led is quite bright, we liked it a bit dimmed

• Open the file ESP32RET.ino:
  The board will be detected as Macchina A0, so will we go to that section:
  On line 104, you should find the line: 'Logger::console("Running on Macchina A0");'
  Some lines below that, in the same section, edit these two lines to set the correct port for the (probably) speed mode:

   124 pinMode(13, OUTPUT);   --> pinMode(23, OUTPUT);
   125 digitalWrite(13, LOW); --> digitalWrite(23, LOW);

Then set the correct ports for the canbus by editing this line:

   133 CAN0.setCANPins(GPIO_NUM_4, GPIO_NUM_5); --> CAN0.setCANPins(GPIO_NUM_26, GPIO_NUM_27);

• In your Arduino IDE Sketch, select board: 'LilyGo T-Display'. On first selection of the board it will ask to install 'esp32', click yes and let it install.
• You need the FastLED library. Go to Tools -> Library Manager en search for 'FastLED'. You should then find 'FastLED by Daniel Garcia'. Install this one.
• You also need three libraries from the same github-page as the ESP32RET firmware:
  Visit https://github.com/collin80/esp32_can and click on the green 'Code'-button and choose 'Download ZIP' in the submenu
  Visit https://github.com/collin80/can_common and click on the green 'Code'-button and choose 'Download ZIP' in the submenu
  Visit https://github.com/collin80/esp32_mcp2517fd and click on the green 'Code'-button and choose 'Download ZIP' in the submenu
  Extract all the zip-files, remove the 'master'-suffix, and move the content to the libraries-folder. In the end your directory structure should look like this:

 └── Documents/
     │
     └── Arduino/
         │	
         ├── ESP32RET/
         │   ├── can_manager.cpp
         │   ├── can_manager.h
         │   ├── ..
         │   ├── config.h
         │   ├── ESP32RET.ino
         │   ├── ..
         │   ├── wifi_manager.cpp
         │   └── wifi_manager.h
         │
         └── libraries/
             ├── can_common/
             ├── esp32_can/
             ├── esp32_mcp2517fd/
             └── FastLED/

• Next step is to compile and upload the sketch. The compiling may take some time on slower computers with a new Arduine installation (up to 30 minutes)
  If the compilings succeeds and the uploading is finished, the built-in led of the board will turn green.
• In SavvyCAN, Go to Connection -> Open Connection Window, click 'Add New Device Connection', pick the first option 'Serial Connection (GVRET)'. The Serial Port will autodetect. Click 'Create New Connection', and you should be all set.

[nagup]

Hi thank you for creating this guide, for me it works for the most part, I have it conencted in savvycan with a green light however I dont see any can frames coming through, did you get any frames to appear? If so what version of savvycan were you using and do you also connect the GND of the CAN terminal to the can network GND?

Do you do any other tests or checks to verify that the lilygo tcan485 is working correctly?

At first I was thinking maybe the CAN transceiver is not working but pin 23 is being pulled low in the code so it should all be ok.

If you still have access to the complete firmware file would you mind sharing that too just in case there is a difference that got overlooked?

Thank you for your time

[floeplala]

Hi Nagup, nice you see you are interested. I don't remember which version of savvycan I used, probably the newest at that time. I connected it to the canbus of my car and I did also connect the ground of the can-bus to the ground of the card. Troubleshooting is a bit of a problem, it doesn't work till it does. I almost borrowed a oscilloscope to check the signals, but I got it working just before that. About the firmware-file: In Arduino IDE, I tried Sketch -> Export Compiled Binary, but that results in an error. Is that what you mean? I can send you a zipped file of my Arduino-folder. Did you check if you have the right termination for your canbus? I believe the board has a built in termination resistor. If the board is an endpoint that is ok but if you just tap the bus somewhere (like a T), you don't want a resistor. In that case you might be lucky when you extend the wires a little.

[nagup]

Thank you a lot for getting back to me.

Yes a zipped file of the project will be perfect, then I can look for any differences in mine vs yours and hopefully I find something missing in mine so I have something to explain why it wasn't working.

Since you were using it as a T, I may have to try that as well. So far ive had it directly connected to an arduino Uno with can shield, also has a resistor so its all properly terminated afaik. The arduino is sending a message every 500ms.

Roughly how long ago were you doing this? I'll try different versions from that time and read the release notes maybe something has changed, which I should also see when comparing your project vs mine.

Do you remember anything about the device console? You can see it in the device connection menu, on mine i get repeated 4 bit messages, and sometimes when a message is sent from the shield, the console shows a huge message of up to 64 bits, sometimes random data and sometimes mostly 0's so i am going to do more testing with speeds maybe its to do with that.

[floeplala]

Hi, when the termination is ok I guess you don't have to try the T-setup. I temporarily placed the file in my https://github.com/floeplala/BMW-F20-KOMBI-Cluster-Bench-testing repository (Arduino - kopie - temp). The file has libraries for my other projects as well, you can ignore those. About the device console: I got immediate overloaded with data once connected, but that is because the canbus of the car is quite busy. This was in May/June 2025.

[hmeier9999]

hi Nagup, Is possible to get also a zipped file of your Arduino-folder?

[floeplala]

The zip-file was too large to upload, but I removed one library that belongs to another project, and now it fits. See: https://github.com/floeplala/BMW-F20-KOMBI-Cluster-Bench-testing/blob/main/Arduino%20-%20kopie.zip

[nagup]

Hi,I made a small guide here #1002 (comment) let me know if it works for you On 29 Oct 2025, at 08:29, hmeier9999 ***@***.***> wrote: hi Nagup, Is possible to get also a zipped file of your Arduino-folder? —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you commented.Message ID: ***@***.***>

[hmeier9999]

Hi floeplala, I would like to test it with LILYGO T-CAN485 board and I don't get it running with the version to be compiled. However, a tried the precompiled version (https://www.savvycan.com/ESP32RET_Updater.zip) and is connecting properly, no issues.
The challenge is now to get the correct setup for LILYGO T-CAN485 board with the change you well have descripted it. Thx for that.
Is it possible to get you compiling folder zipped?

[floeplala]

I uploaded my Arduino-folder to: https://github.com/floeplala/BMW-F20-KOMBI-Cluster-Bench-testing/blob/main/Arduino%20-%20kopie.zip
I hope this is helpful. You can ignore some of the libraries, they belong to other projects,

[hmeier9999]

Thank you very much for your support. I’ve tested it, but unfortunately it’s still not working.

When trying to connect to the SavvyCan software, I get the following output:
Connecting to GVRET Device!
Write to serial -> e7 e7 f1 c f1 6 f1 7 f1 1 f1 9
Failed to connect to GVRET at that com port

This is the same issue I’ve encountered during my previous attempts. With the precompiled version this is working ... very special!!!

[gconlon]

Thanks for the guide. Am I missing something? There is no ESP32RET.ino in the ESP32RET-Master.ZIP file that I downloaded