I have a Particle Electron board which I am using for a project and after leaving it powered on last night with battery+power supply @ 9V (using VIN pin) I cannot get it to boot.
The firmware led does not come on, only the small RED led next to lipo.
The LED does not come on when I use USB or battery (which might be dead) or both.
Only when I power the VIN pin does the red led come on:
Pressing reset button and/or mode does nothing and the firmware LED does not turn on so I do not think it is booting at all.
I think maybe the PMIC is damaged?
Is there anything else I can try?
Is the blue LED next to D7 on dimly? That usually indicates a corrupted flash and the bootloader cannot be run.
The charge LED is driven by the PMIC, so it’s at least partly working and the USB port has power.
If you have a voltmeter, you can check the voltage on 3V3. Also check pin D7.
To make sure the firmware isn’t putting the device asleep really quickly, hold down MODE and tap RESET. That’s probably not the case because the status LED usually blinks white briefly before going back to sleep.
If you haven’t done so, disconnect both the battery and USB power and let the device sit for 30 seconds so it’s completely discharged before plugging in the USB power. With USB powered but the battery disconnected the charge LED should flicker.
3V3 has no output at all until I put power on VIN, but it is only reading 0.213V on the voltmeter.
D7 is 0V in all cases.
RESET+MODE is not responsive.
If I don’t use VIN pin, there are no LEDs powered on so I am not sure that USB is providing any power.
Could the battery dying while connected cause a problem?
I guess it’s probably the 3.3V regulator (TPS62291), not the PMIC (bq24195), but it could be either. Running the battery down won’t affect either of those chips, but it could cause the Dim D7 issue, which is not the problem you are seeing. In any case, it’s most likely a hardware failure that’s not easily fixable, unfortunately.
That sucks.
I already ordered a PCB with this on it.
I guess I could try replacing those parts - but I could (and probably would) damage something else in the process.
Is there a way I can mail it in for a replacement?
could this electron be suffering from this problem from a long time ago?
One theory could be that the usb cable is broken, it did not provide power during the night this was ON and the Electron discharged the battery, leading to this.
I probed some test points and the 3V3 is measuring 0.3V. I scoped the output of the IC (see below) and I think it looks ok. Then I thought it could be the 10uF cap so I checked that and it is good - so that leads me to think it could be a problem with the inductor. I tried to check its resistance to see if there’s any issues there but I couldn’t really get to the pads. I might need to lift it off the PCB to test it - I’ll try that when I get more time to work on it.
I can see in the datasheet that they part from the reference implementation by not including the resistors and small cap.
Here is the circuit in question:
If you have a 3.3V bench supply, try briefly powering the device via the 3V3 pin. This is not recommended as it can damage the regulator, however there’s a good chance the regulator is already damaged. If the status LED turns on (probably white to start), then that is a good indication that the STM32 is still OK. Don’t leave it powered for long, and the device will not fully start up without the 3V8 power supply anyway.
