DiyBms controller comms not working correctly

Hardware diyBMS
1

I am currently trying to put together an all in one 16s board and controller for a battery project I have going on. I have the controller and 16s boards built. When I connect the 16s module to the controller the two do not seem to communicate. The controller says waiting for modules. After verifying that the cables were connected correctly I hooked a logic analyzer to the comm cable. I could see both the output to the module and the response back.

After I verified that there is data flowing between the controller and the module I checked the ESP32, pins IO32 (TX) and IO2 (RX). Both pins had data on them. I took a look at the controller code and enabled some printouts, I can see in the serial output of the ESP32 that the module is sending messages and the LED on the module board is blinking in time to those sends. And I know data is flowing back to the controller but I am not seeing any receives in the console log. I am guessing that something is not configured right but am not sure what.

Controller

  • FW: main branch commit f909d31 (started using Compiled_Firmware_2025-03-30-15-36)
  • PCB: revision a7527b7

Module

  • FW: module_fw_V490_AUTOBAUD_VREF4500_genericSTM32F030K6T6

Any help would be appreciated.

2

have you changed the settings?

image
image526×273 12.8 KB

3

Got it working!!

TLDR: Q4 was bad

I was trouble shooting the board looking at the data that was coming back on IO2 trying to decode the message to the module and the response from the module. I noticed that the data on IO2 did not look as nice as the data on IO32

ControllerDataSnip
ControllerDataSnip542×391 1.94 KB

It wouldn’t decode with my Logic analyzer either, not nicely anyway. So I checked the data coming into the controller board and it looked fine. So the problem was between the data connector and the ESP32, I soldered in some hookup wire and checked the signal on the other components to the communication circuit and the output of Q4 was where the signal went bad.

ControllerSetup
ControllerSetup1712×1289 445 KB

Replaced Q4 and everything worked. I don’t think that I could have found the problem without some sort O-scope/Logic Analyzer. Now on to the next step of hooking up the current shunt and setting up a test system to play around with.

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