Consequence of tin droplet on the SPIN debugger connector

General
1

Dear OwnTech community,

I’d like to get your diagnostic for this strange accidental situation where a SPIN board received a tin (solder) droplet on its STLINK debugger connector.

Here is a picture:

photo of SPIN microcontroller's debugger connector with tin droplet
photo of SPIN microcontroller's debugger connector with tin droplet1115×943 428 KB

It seems that the 6 bottom pins are electrically connected. Comparing with the SPIN pinout, this translates into 4 pins (2 are not connected):

  • GNDDetect
  • STLINK_RX
  • SWDIO
  • SWDCLOCK

Question: what should be the theoretical consequences of it?

I can only bring the practical consequence I observed: device doesn’t respond on USB port. Is this to be expected?

2

Hello Pierre,

Thank you for your question.
I’m really sorry for the long delay to answer you, I will try my best to keep up with this thread going forward.

When looking at the SPIN schematic and routing as attached:

image
image2045×510 97.9 KB

Your blob is located on the six pins to the right.
These pins are shorted together, which pulls your RST to the ground.
This is exactly how you reset the SPIN :

image
image779×455 20.1 KB

This means your spin is being reset all the time, potentially explaining why you have nothing on the USB.

To test this I made it fail in two ways:

  • I connected an ownverter to my computer, put it in recovery mode and then used an aluminum foil to short the two pins. If there is a reset, the second LED should turn off. It does. Here’s the before and after.

image
image1753×968 240 KB

  • I ran a lsusb command on the terminal and then shorted the pins. If there is a reset state, the board should not be listed. This is exactly what happens to me here:
luiz-villa@hp2-owntech:~$ lsusb
Bus 003 Device 055: ID 2fe3:0100 NordicSemiconductor OWNVERTER_V1_1_0
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
luiz-villa@hp2-owntech:~$ lsusb
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

So, I suppose you will have to clean this before using it again.

1 Like
3

Thanks a lot for the feedback. It’s reassuring that the “theory” of the schematic explain the symptom. Also reassuring is the fact that this short circuit is not in principle a damaging one.

So hopefully once the tin is removed, the board should behave properly. Fingers crossed!