I am building a sensor that works when it is connected to my laptop through the USB. the LED lights up and I can record the sensor changes over time, however, when I disconnect the USB and connect it via a 9 V battery power supply, the LED indicator and essentially the circuit stops working. I tried switching the power supply off, and the LED flickers for only a fraction of a second when I do that. I am using a NodeMCU. Confused about what to do since I have tried checking for loose connections or wrong connections.
What 9V battery? Like the below one which is totally not suitable for use in the microcontroller world?
Which exact NodeMCU? ESP8266 or ESP32 based?
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How is OP connecting their battery?
Schematic please.
Try a brand new unused battery.
Push the reset button
3 reasons why not to use classic 9V battery with your board:
Nodemcu is designed for 5V on VIN, while it probably can handle more, it's not suggested.
Cheap/used 9V battery might not be able to give current Esp8266 needs at peak.
Battery-life is bad, 2/3 of the capacity is waisted to convert voltage to 3.3V
3-4 AA batteries would work much better.
Yes, unfortunately, that is the only power supply I have on me right now since it came along with the kit. It's an ESP8266-based NodeMCU.
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