LilyGO T-Echo Lite displaying incorrect battery voltage

[pelgraine]

I have a T-Echo Lite Core (screenless version) flashed with the Meshcore v1.11 companion BLE firmware for the T-Echo Lite. It displays as 6.00v when a battery is connected, and also when no battery is connected and it's on USB C mains power. I'm using the iOS app. This error occurs when I've tried the Makerfocus 3.7v 1100mah battery, a generic li-on 3.7v 2000mah battery, and a Makerhawk 3.7v 3000mah battery.

I've also tried changing the adcvalue in this bit of techoboard.cpp to 0.61 or 0.62 and it still reads as a 6v battery input regardless.

[pelgraine]

Update: Have been trying to fix it with my zero coding experience. I changed PIN_VBAT_READ in TechoBoard.h from 4 to 2, after consulting the LilyGo GitHub docs, and it appears to have improved things somewhat though still isn't reading things correctly. I now get varying voltages at least instead of just 6v when connected to everything/anything, but the readings are still much too high.

[IoTThinks]

It shows 6v for my T-Echo Lite repeater also.
From both battery and usb-c.

[IoTThinks]

Have you checked this?

https://github.com/Xinyuan-LilyGO/T-Echo-Lite/blob/main/examples/T-Echo-Lite/Battery_Measurement/Battery_Measurement.ino

[andywilliamsuk]

That's okay. My Heltec v3 says 16V!

[IoTThinks]

@andywilliamsuk Likely faulty HeltecV3 board.

[pelgraine]

Have you checked this?

https://github.com/Xinyuan-LilyGO/T-Echo-Lite/blob/main/examples/T-Echo-Lite/Battery_Measurement/Battery_Measurement.ino

Yes. That is how I figured out I needed to change it from pin 4 to pin 2. Other than that I don't know what to do with the rest of that information so was hoping a developer might be able to take a look.

[IoTThinks]

I asked the Lilygo guys.

Let me try and fix.
Xinyuan-LilyGO/T-Echo-Lite#9 (comment)

[IoTThinks]

@pelgraine I have attempted to fix it.
Tested the fix with power meter.

You may try it and let me know if it works for you.
If you want a pre-compiled bin file, let me know if you are using T-Echo Lite companion or T-Echo repeater.
#1198

[pelgraine]

@pelgraine I have attempted to fix it. Tested the fix with power meter.

You may try it and let me know if it works for you. If you want a pre-compiled bin file, let me know if you are using T-Echo Lite companion or T-Echo repeater. #1198

Thanks so much for giving it a go! I copied the code in 1198 and amended it into VSCode, and it appears to have entirely disabled Bluetooth in the companion BLE firmware version. So I compiled the repeater version as well and that reads as 100% 4.2v regardless of whether I plug in a full 3.7v lipo battery, a half-flat 3.7v lipo battery, or usb power.

I probably did something wrong - would you mind compiling the Companion BLE version for me, please?

[IoTThinks]

Ok, I will compile and test it with my T-Echo companion today.

[IoTThinks]

Try this uf2.
To enter DFU, press and hold RESET button until the BLUE led flash, then release RESET.
Then quicly press and release RESET.
It will open a drive for you to put in the uf2.

https://github.com/IoTThinks/EasySkyMesh/blob/main/firmware/Testing/companion-techo-lite-v1.11.0-fixed-batteryreading.uf2

This is my testing.
Remember: To take out the usb cable to measure and to use the battery only. Else it will display 4.2v all the way.
If I set the voltage around 3.3v, the reading is around 3.2v, then the code will shutdown the companion to avoid deep discharge.
This is expected.

[pelgraine]

Try this uf2.
To enter DFU, press and hold RESET button until the BLUE led flash, then release RESET.
Then quicly press and release RESET.
It will open a drive for you to put in the uf2.

https://github.com/IoTThinks/EasySkyMesh/blob/main/firmware/Testing/companion-techo-lite-v1.11.0-fixed-batteryreading.uf2

This is my testing.
Remember: To take out the usb cable to measure and to use the battery only. Else it will display 4.2v all the way.
If I set the voltage around 3.3v, the reading is around 3.2v, then the code will shutdown the companion to avoid deep discharge.
This is expected.

Thanks for that. Tested that this morning with my existing TEcho Lite and it shows 100% 4.2v which is incorrect for that particular battery. Battery should be closer to 50% as it's been on for a few days. Didn't have time to test further or flash my other Lite nodes but will try again later today.

If you're testing with a T-Echo I wonder if the pins/measurement etc are different with the Lite? I have the screenless 915mhz version. Thinking this firmware is just copied from the T-Echo firmware and we might actually need a new/fresh firmware build for the Lite.

[IoTThinks]

@pelgraine By right yes, T-echo and t-echo lite should have the same Pin mapping.
However, in Lilygo github, it seems that the pin mapping is different for T-echo and T-echo lite.
One reads from GIPIO2 and one reads from GPIO4.
Lite needs to enable Measure GIPO to read while T-echo doest.

Are you sure that you unplugged the USB-C for T-echo lite while testing?
If you put in USB-C, it will always show 4.2v which is expected and correct.

[pelgraine]

@pelgraine By right yes, T-echo and t-echo lite should have the same Pin mapping.
However, in Lilygo github, it seems that the pin mapping is different for T-echo and T-echo lite.
One reads from GIPIO2 and one reads from GPIO2.
Lite needs to enable Measure GIPO to read while T-echo doest.

Are you sure that you unplugged the USB-C for T-echo lite while testing?
If you put in USB-C, it will always show 4.2v which is expected and correct.

Yes, absolutely was unplugged from USB.