@ajb2k3 thanks so much for that insight. Do you have an implementation of HV write mode for the Paper display in a different platform (UIflow etc)? Don't worry if not, because it seems that existing shutdown() is able to retain images according to @felmue's example.

As mentioned in the other thread, the missing step is transferring the canvas framebuffer to the EPD.
If your loop function is changed as below, it works as you expect.

void loop() { for (int i=1; i<7; i++) { canvas1.drawString(testString[i],20,20); /* m5epd_err_t UpdateArea(uint16_t x, uint16_t y, uint16_t w, uint16_t h, m5epd_update_mode_t mode); */ M5.EPD.WriteFullGram4bpp((uint8_t*)canvas1.frameBuffer()); M5.EPD.UpdateArea(0,0,100,100,UPDATE_MODE_GL16); delay(1000); } }

Hi @Powersoft please don't double post, and refer to my reply on your other post

I've just started out but it looks like the following shows the voltage and mine maxed out at 4.178V, this gradually decreases and I think below 3.6V isn't really usable. You can use this and some testing to determine the percentage of battery.

#include "M5StickCPlus.h" TFT_eSprite Disbuff = TFT_eSprite(&M5.Lcd); void setup() { M5.begin(); M5.Axp.ScreenBreath(8); M5.Lcd.setRotation(1); Disbuff.createSprite(240, 135); Disbuff.setTextColor(TFT_WHITE); } void loop() { Disbuff.fillRect(0, 0, 240, 135, TFT_BLACK); Disbuff.setCursor(10, 10); Disbuff.printf("BAT_V: %.3fV",M5.Axp.GetBatVoltage()); Disbuff.pushSprite(0,0); }

There are other options power functions that may help in this doc:
AXP192 (Power management)

Good luck.

it's a library to control a sensor, I had already built my custom blocks that worked with that library, but when I updated everything I was unable to make it go.
so do I have to import the library into the / flash root?

and then?

I have achieved quite good results with the Seeed Studio Grove 3-Axis Digital Compass V2.
https://wiki.seeedstudio.com/Grove-3-Axis_Digitial_Compass_v2.0/