Is my Lopy4 dead ?

[pjuhen]

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 erase_all
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]

How did you connect your smartphone battery to the LoPy4?

[pjuhen]

With an USB cable through the expansion board. Le 03/05/2022 à 08:51, Robert Hammelrath a écrit :

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How did you connect your smartphone battery to the LoPy4? — Reply to this email directly, view it on GitHub <#593 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AKKQX6QES6YVZE7PIHY5X6DVIDEGHANCNFSM5U56SGVQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[robert-hh]

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

[pjuhen]

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 :

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That sounds safe. Do you have a voltmeter to check, if the supply voltages 5V and 3.3V are present at the LoPy? — Reply to this email directly, view it on GitHub <#593 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AKKQX6QVROH5VPFD44GBDYDVIDGUJANCNFSM5U56SGVQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[robert-hh]

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]

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? — Reply to this email directly, view it on GitHub <#593 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AKKQX6QVROH5VPFD44GBDYDVIDGUJANCNFSM5U56SGVQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[robert-hh]

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]

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 :

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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. — Reply to this email directly, view it on GitHub <#593 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AKKQX6QVSJB732LTHTA7BM3VIDZ5DANCNFSM5U56SGVQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[pjuhen]

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