Topics created by ckuehnel

Hello @ckuehnel glad to hear and thanks for letting me know. Thanks Felix

Hello @ckuehnel Without opening M5CoreInk you probably cannot measure battery voltage with a multimeter. However you can use GPIO35 to read the battery voltage. Check out float getBatVoltage() here. BTW: I've opened my M5CoreInk today and added some photos to my page (link below). Measuring power consumption in light sleep, deep sleep and shutdown will be next. Cheers Felix

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Thanks for posting that info, djhopkins2, it's hard to come across! I have found that this function keeps the board from shutting off after a few seconds, but I only started using an hour ago; I don't know if it has any adverse effects on the hardware yet: void disable_shutoff() { return M5.I2C.writeByte(0x75, 0x02, 0x00); } Also, here are the corrected voltage and current functions alluded to above; I don't think the voltage can go negative, but the current certainly does, and displays meaningless values without this correction: int16_t readBatV(uint8_t Reg) { uint8_t dataV[2] = {0, 0}; M5.I2C.readBytes(0x75, Reg, 2, dataV); if(dataV[1] & 0x20) dataV[1] |= 0xC0; // 14 bit 2's complement to 16 bit return (dataV[1]<<8) | dataV[0]; } int16_t readBatI(uint8_t Reg) { uint8_t dataI[2] = {0, 0}; M5.I2C.readBytes(0x75, Reg, 2, dataI); if(dataI[1] & 0x20) dataI[1] |= 0xC0; // 14 bit 2's complement to 16 bit return (dataI[1]<<8) | dataI[0]; }

@ckuehnel Did you ever figure this out? I just got my 18650 hat. I took it apart and also don't see any control circuitry. I'm now guessing that the USB connector on the hat simply feeds into the 5V input of the M5StickC, and the AXP192 inside the M5StickC controls the charge of the 18650 cell. There is some info in the AXP192 data sheet about a back-up battery, but it's been a while since I read it, and I'm not sure it's relevant. One interesting thing ... I'm working on a project where I turn the display off after a few seconds if the M5StickC is not plugged in. Either by shrewd design or by my dumb luck, that works when the M5StickC is on the hat. ("It works" means the display turns off after a few seconds.)

@grelm I think (but i could be wrong) 10mA should be ok.