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pycom / pycom-micropython-sigfox

A fork of MicroPython with the ESP32 port customized to run on Pycom's IoT multi-network modules.
MIT License
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Is my Lopy4 dead ? #593

Open pjuhen opened 2 years ago

pjuhen commented 2 years ago

Hi,

I have a Lopy4 on an expansion board v3.1.

Up to yesterday, I used it connected to my PC.

Yesterday, I plugged a smartphone external battery instead of the PC, to run it oudoor.

Since then the orange LED doesn't light, and the Lopy4 seems dead.

The expansion board is OK, I was able to do a firmware upgrade.

But I have no echo on the REPL.

When I try a firmware upgrade, here is the result :

sudo ./pycom-fwtool-cli --debug -p /dev/ttyACM0 -s 115200 eraseall Running in PIC mode Erasing the board can take up to 40 seconds. Connecting to ESP32 with baudrate: 115200 Product ID: 152 HW Version: 7 FW Version: 0.0.11 Connecting........____............................................._____ Exception: Failed to connect to ESP32: Timed out waiting for packet header

Is my chip dead ?

Thanks,

Regards,

robert-hh commented 2 years ago

How did you connect your smartphone battery to the LoPy4?

pjuhen commented 2 years ago

With an USB cable through the expansion board.

Le 03/05/2022 à 08:51, Robert Hammelrath a écrit :

How did you connect your smartphone battery to the LoPy4?

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robert-hh commented 2 years ago

That sounds safe. Do you have a voltmeter to check, if the supply voltages 5V and 3.3V are present at the LoPy?

pjuhen commented 2 years ago

It seems I have 5V on Vin but nothing on 3.3V.

Thanks,

Regards

Le 03/05/2022 à 09:12, Robert Hammelrath a écrit :

That sounds safe. Do you have a voltmeter to check, if the supply voltages 5V and 3.3V are present at the LoPy?

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robert-hh commented 2 years ago

Then, the 3.3v regulator is broken, or there is a short in the 3.3V line to GND, either at the LoPy4 or the expansion board. Broken regulators used to happen in the past only when one tried to feed the board through the 3.3V pin (misleading doc), or when the input voltage is too high. Otherwise the regulator is pretty robust and survives shorts and overload. Replacing the regulator is almost impossible. When that happened in the past, people removed the regulator and supplied the board with 3.3V. But for most people that is no way to go.

pjuhen commented 2 years ago

I would say the regulator is dead.

I didn't find my voltmeter, but I did a small controller with a LED and a resistor.

3.3 is OK (lights the LED) on an ESP32 and an Arduino, but not on the Lopy4.

So, seems that my external battery delivered something that killed the regulator.

Is it the expansion board or the Lopy4 ?

Thanks,

Regards,

Le 03/05/2022 à 09:12, Robert Hammelrath a écrit :

That sounds safe. Do you have a voltmeter to check, if the supply voltages 5V and 3.3V are present at the LoPy?

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robert-hh commented 2 years ago

The regulator is on the LoPy4 board. If there is no signal at the 3.3V pin while sitting on the expansion board, the reason could be: a) broken regulator on the board. The regulator dies at 7V input voltage or when reverse voltage > 3.3 V is applied to the output. b) a short to GND either on the LoPy4 or the expansion board. Choice a) is more likely. Choice b) could be tested with a Ohmmeter.

pjuhen commented 2 years ago

I did nothing special exepct pluging a powerbank. Maybe this one has delivered a peak (it's old).

I ordred a multimeter. More tomorrow...

Thanks,

Le 03/05/2022 à 11:56, Robert Hammelrath a écrit :

The regulator is on the LoPy4 board. If there is no signal at the 3.3V pin while sitting on the expansion board, the reason could be: a) broken regulator on the board. The regulator dies at 7V input voltage or when reverse voltage > 3.3 V is applied to the output. b) a short to GND either on the LoPy4 or the expansion board. Choice a) is more likely. Choice b) could be tested with a Ohmmeter.

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pjuhen commented 2 years ago

I think the powerbank was broken and sent a power pulse that killed the regulator. After that, both powerbank and lopy4 were dead.