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matthias-bs / BresserWeatherSensorTTN

Bresser 5-in-1/6-in-1/7-in-1 868 MHz Weather Sensor Radio Receiver based on ESP32 and RFM95W/SX1276 - sends data to a LoRaWAN Network (e.g. The Things Network)
MIT License
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Thingpulse ePulse Feather & Adafruit LoRa Radio FeatherWing Battery Power Stability #56

Closed matthias-bs closed 1 year ago

matthias-bs commented 1 year ago

The Thingpulse ePulse Feather & Adafruit LoRa Radio FeatherWing setup works as expected when powered via USB port.

When powered from the battery connector (CN1 in the schematic - net label VBAT), the brownout detection is triggered after initialization of the LoRa radio in case the battery voltage is below ~4.0 V. This is indicated by the message Brownout detector was triggered in the serial console.

Adding a small electrolytic capacitor (0.22 or 2.2µF) to either VBAT, VBUS or 3V3 [with jumper wires] did not solve the issue.

It it is expected that operation from a lithium-ion battery is possible at least down to ~3.6 V.

matthias-bs commented 1 year ago

@marcelstoer Any ideas about how to resolve this?

matthias-bs commented 1 year ago

Solved

The issue was caused by an ampere-meter in-line with the lab power supply. (Old Metex M-3650CR - unfortunately, the impedance is not provided in the manual.)

However, the same setup did not cause any issues with the other ESP32 boards I tested. So, the power supply impedance seems to be more critical in this case. It should not be an issue with a battery directly connected, but might for instance have to be checked with a PV charger's output.