No telemetry on INA260 with LTO.

[spairo1741]

• I built an ESP32 node and programmed it as a DIY ESP32 using a web programmer
  and firmware 2.7.13 FW+ v81 from https://loranet.pl/firmware
• Everything works, except for the telemetry from the LTO battery.
• Below is the device's operation log.
• On the RAK4630 node, telemetry on the INA260 works without any problems.
• Is there a simple way to fix this, or should I just give up on the INA260?

20260127_144525_Rs232SaveLog.zip

[slintak]

Hi @spairo1741, thanks for the log and the details.

I double-checked yesterday and the INA260 emulation in the LTO firmware works on RAK4630, so this really looks like an ESP32-specific issue. In your log I see:

[Wire.cpp:513] requestFrom(): i2cRead returned Error 263
[13348][E][Wire.cpp:499] requestFrom(): i2cWriteReadNonStop returned Error 263

This is from the Arduino I2C implementation on ESP32 (Wire.cpp). I don't have much experience with Meshtastic on ESP32. The LTO firmware was developed and tested first on RP2040 (Raspberry Pi Pico) and later on RAK4630. I have not tested it on ESP32/Arduino yet.

One possible cause is a difference in how the ESP32 master reads registers. The log mentions i2cWriteReadNonStop, which usually means a combined write and read transaction using a repeated start (write the register address, then read the data without a STOP in between). If my I2C slave implementation is not fully compatible with this pattern, the ESP32 side can time out.

When I get some time, I will try to reproduce this on ESP32 and see exactly what the master is doing and where it fails. Could you share a bit more information about your I2C bus wiring, please?

1. What pull-up resistors do you have on SDA and SCL (values and where they are located)?
2. What else is on the same I2C bus besides the LTO BMS (display, sensors, etc.)?

[spairo1741]

• The SDA and SCL resistors are not located on the ESP32's proprietary board.
• The resistors are usually located on the I2C interface boards.
• A Meshtastic board with an ESP32 typically has at least a BME280, INA219, and SH1106 onboard.
• All I2C.