@ckuehnel https://github.com/m5stack/meshtastic-firmware/tree/develop go to this repo and build the firmware yourself pin config is at variants/m5stack_corebasic/variants.h

@ckuehnel said in Measuring the Water Temperature: Because I was not satisfied with the information about the water temperature of the Baltic Sea during a past vacation stay, I built a thermometer with M5Stack components and a remote temperature sensor and presented it in a blog post. With the remote DS18B20 temperature sensor, I measured the water temperature at a depth of one meter. Now the vacations are approaching again, and the message from the BSH still shows very cool water at the end of May. I have extended the presented thermometer to follow the water temperature changes and be immune from bigger surprises. Because of the slightly larger display, I replaced the M5StickC with an M5StickC+ and used an M5StickC 18650C to increase the battery capacity. In addition, the thermometer is much easier to handle. To have the readings available on my mobile phone, I use it as a mobile hotspot and send the readings from the M5StickC+ via WiFi to the mobile phone, which then sends the data to the Pushover server. From there, the data is then distributed to the selected end devices. This setup won't affect the water temperature, but I can record it in writing. And if it stays that cold, then I can document my heroism. That's really impressive! Building your own thermometer to monitor the Baltic Sea's water temperature is a unique approach. Upgrading to the M5StickC+ with an M5StickC 18650C for more battery capacity sounds like a smart move. And the data transmission setup using your mobile phone as a hotspot and Pushover server is clever! It may not change the water temperature, but it's great for keeping records. Thanks for sharing, and here's the temperature converter link you mentioned: temperature converter. Good luck with your upcoming vacation and documenting your heroism! 😄🌊🌡️

Hello @ckuehnel could you share some additional information? E.g. which M5Stack core is it connected to? which Groove port are you using? how do you initialize the serial connection? which GPIOs are you using for TX and RX? could you share your UiFlow or Arduino code? Also these SIM7xxx modems take some time to initialize before they react to AT commands. Try sending the AT command a couple of times. Thanks Felix

@twostick FYI; light sleep current pulled out of the battery depend on the battery voltage: <2.7V device wont wake up anymore 2.7V 4.4mA 3.0V 3.9mA 3.7V 3.1mA 4.2V 2.7mA This dependacy is caused by the DC-DC conversion that converts the Lipo voltage first to 5Vdc. (SY7088 chip). The 5Vdc gets also down converted to 3v3 (SY8089 chip) . According to the datasheet, the ESP itself should only use 0.8mA in light sleep. So 2mA gets waisted. What a pitty. dd.07-04-22: The above is not completely true. I'm using the M5GFX lib and when I execute the function display.sleep(); before going to deep sleep (esp_deep_sleep_start();) the sleep current drops to a 1.25mA. Still considerable...

@m5stack It works now as expected.

Hello @ckuehnel I did some experiments with the ATECC608A version in the M5Core2 AWS kit. Using the aforementioned libraries with I2C address 0x35 I can make it wake up and read information from it. However for me it did not show up using an I2C scan, even after waking it. From the full datasheet I understand that 0x35 is the default I2C address which can be modified exactly once to something different. Looks like that has not yet happened with the ATECC608A in my M5Core2 AWS kit. In contrast the M5Stack ID Unit uses the ATECC608B version for which I was not able to find the full datasheet (it looks like it requires an NDA). I assume that either the same mechanism exists regarding I2C address for the B version and 0x60 is the default or it already has been modified from 0x35 to 0x60 by M5Stack. (I don't have the M5Stack ID Unit so I cannot confirm whether it uses 0x35 or 0x60.) Thanks Felix

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.