Brownout on battery --> starting bluetooth

lemmingDev commented 6 years ago

Hi

If I start my board on battery power it keeps restarting when I call:

BLEDevice::init("ESP32"); // start bluetooth

If I start the sketch with USB cable in, it works fine If I start it on battery power, it will bootloop due to brownout, but then if I plug the USB in, it will start working fine.

I put some debugging messages to the OLED, and it happens as soon as I call BLEDevice::init("ESP32"); , and when I check the reset cause, it returns 12 --> SW_CPU_RESET --> which a brownout

The strange thing is, if I remove the USB cable after the sketch is running fine, it will work just fine on battery power. Battery is a 1500mAh 18650 Li-ion

This happens on TTGO LORA32 V2 - I have 2 boards and both exhibit this behaviour

On TTGO LORA V1, it works fine starting on battery and I have no issues - I have 2 boards and both are fine

Can someone please offer help?

lemmingDev commented 6 years ago

Just checked - same issue occurs on starting wifi --> WiFi.scanNetworks();

Does having the USB cable in for a short time charge up some kind of capacitor that prevents brownout occurring?

lemmingDev commented 5 years ago

Hardware design error?

corck commented 5 years ago

I've the same problem as you describe, actually haven't found out whats causing it.

lemmingDev commented 5 years ago

Doesn't look like they're willing to make a comment okn the issue...

lyusupov commented 5 years ago

@lemmingDev : see if this workaround (1000uF electrolitic capacitor on 3.3V power rails) can help you.

LilyGO / TTGO-LORA32

Brownout on battery --> starting bluetooth #18