Bricked two Pro Micro boards, why?

Development Boards Arduino
1

Hi. I had two pro micro boards, and I was using them to test the Hall effect sensors of my motor in following setup as on this picture:

UPDATE: RAW is almost 5V, comes from USB port, probably after a LED that shows that the board is powered on. Boards were 5V/16MHz.

Motor has 8 outputs: 3 for power, they were not connected, and 5 for Hall effect sensors: ground, +5 volt, and 3 for sensors output.

My code was extremely simple:

#include "Arduino.h"
 
void setup()
{
  // initialize serial comms
  Serial.begin(9600); 
}
 
void loop()
{
  // read A0
  int val0 = analogRead(0);
  // read A1
  int val1 = analogRead(1);
  // read A1
  int val2 = analogRead(2);
  // print to serial
  Serial.print(val0);
  Serial.print(" ");
  Serial.print(val1);
  Serial.print(" ");
  Serial.print(val2);
  Serial.print("\n");
  // wait 
  delay(50);
}

On the computer I was reading the serial port and plotting the results.

Both boards worked for some time, and then stopped. Now they are not recognized by my computer at all, by this I mean: I use linux, and there’s nothing in dmesg when I connect the boards.

I wonder what happened. Did I do something wrong? I ordered 5 new boards, and I wouldn’t like to brick them all too…

2

And what is “RAW”?

3

What was the raw voltage ? Were the MCUs 5V/16MHz or 3.3V/8MHz ? What part was the Hall sensor ? There’s nothing absolutely wrong that I see in the above, though if the Hall outputs are open collectors and the raw voltage is 12V …

4

“RAW” is almost +5V, see https://learn.sparkfun.com/tutorials/pr … -pro-micro

my board is blue, but seems to be identical to the one in the link otherwise.

If I understand right, “RAW” gets 5V from USB after a LED that indicates that the board is on.

5

These were 5V/16MHz boards. I don’t know what model the sensors are. They are black with three long legs :slight_smile:

6

Khumarahn:
I don’t know what model the sensors are. They are black with three long legs :slight_smile:

While I'm curious as to the thought process that made you connect the Hall sensors as you did, I don't see any way you could have damaged any thing given the above.

Was this some BLDC motor which you spun by hand to see the Hall outputs ? Is there anyway the motor drive wires could have come into contact with the Hall wires ? Is the power LED on ? What do the Tx and Rx LEDs do immediately after power-up and then after some seconds ?

7

I tried to imitate the scheme in motor’s controller - this is why I connected Hall sensors the way I did.

Yes, this was BLDC motor, spun by hand. I am going to check if there could have been a contact between motor drive wire and Hall wires. It should not have happened, unless there is damage in motor’s cable…

Currently the power LED goes on when I plug usb, but RX and TX never blink.

8

…unless the feedback from the hall effect sensors was pushed straight into the pins of the promicro and fried them…

9

Khumarahn:
Currently the power LED goes on when I plug usb, but RX and TX never blink.

Hmmmm, that sounds pretty bricked, or at least boot-coder boffed. I don't have any good suggestions, nor really any good ideas as to what happened.

:cry:

10

I found the the motor’s cable was damaged, and one hall sensor wire may have come into contact with motor wires… Where might have been 36V at the moment.

Is there a way to check, what exactly was burned on my boards?