Fried my pi


(Stephenb123) #1

I was looking forward to getting started with my Raspberry pi 3B+ and iC880A-SPI, but it all went a bit wrong. After connection, my pi failed to boot even after the concentrator was disconnected, and I burned out two SD cards in debugging it.

So, I grounded myself before taking the concentrator out of its ESD protective bag. I connected the antenna to the concentrator, and then connected the two boards via dual female jumper cables for both the power and SPI connections following the “From Zero to LoRaWAN in one weekend” guide https://github.com/ttn-zh/ic880a-gateway/wiki (There were no boards readily available to connect the two and I was hoping to get the device ready in time to give a demo at a local hack-space). I triple checked the pinouts to make sure they were correct! Only at this point did I power up the pi, got lots of happy lights on the concentrator, but from then on no signs of life from the ACT LED on the pi which indicates SD card activity.

I wanted to see if anyone had any similar experiences or could point out any error I might have made - I’m keen to push ahead but reluctant to either cook another pi or buy a new concentrator if the current one is ok!


#2

so you have a non working RPI … :thinking:


(Stephenb123) #3

Yeah, should have specified that the pi was working fine before the connection, and I used it to set up a fresh Raspbian image, connect to the wirless, and enable SPI before powering down and connecting the concentrator.


(Ryan Walmsley) #4

Sounds like the SOC Has had a gpio pin fried or the voltage regulator is playing up.

If the Pi is reasonably new you could possibly RMA it as it could be another fault with it.

Do you have any pictures of the wiring and such or all taken apart?


(Stephenb123) #5

Thanks. Unfortunately all taken apart - I dismantled it pretty quickly when I realised the pi had a fault and I didn’t want to damage the board if it was still good! The pi had served me well as a retro-pi for a few years (I’m doubly sad that one of the SDs I fried was my retro-pi setup with all the saves!) There are no obvious burn marks on anything, there was a smell of burning hardware but I’m pretty sure that was actually the SD card which got pretty hot.

Checking for shorts and the regulator voltage with a multimeter is probably a good idea!

Current plan is, with either this concentrator or a new one, to run another pi of a lower current-rated power supply, begin with only the ground and Vcc pins of the board connected, then connect the rest of the GPIO pins one at a time monitoring for shorts before enabling SPI on the pi - in the tutorials I’ve seen people connect up their concentrators before enabling SPI so presumably connecting it up in this way can’t do it much harm.


(Amedee) #6

This is indeed unfortunate.

I connected quite a lot of times IC880 to RPi’s and never got issues.

Another test you could do is to power directly the IC880 with a lab power supply (or use an amp-meter) to measure the current drain and ensure there is no short on the IC880 which would damage the RPi…

Since I play with RPi’s, I’ve been lucky to only fry one, and a thunder strike was the culprit:
pic-001


(Ryan Walmsley) #7

It is quite weird. How did you connect the power between the ic880a and the Pi? It sounds either like somehow 5V got into one of the GPIO pins or too much current pulled from 3v3. (I’ve heard this is an issue on the 3B+s


(Stephenb123) #8

Power was supplied by connecting pin 2 on the pi to pin 21 on the ic880, and pin 6 on the pi to pin 22.

The ic880a is brand new too of course so I’ve mailed IMST to see if they can take it back for testing - I suspect each board would be QA’d before coming off the line though!


(Stephenb123) #9

The more I read around, the more it seems like a freak pi error - there’s a bunch of people here who ended up with the same problem during normal operation https://www.raspberrypi.org/forums/viewtopic.php?t=140845

SD card was new so possibly it was dodgy (it was Sandisk Ultra). It did seem weird that a fault through GPIO might be causing the SD cards to burn out! I’ll test the board again once I get another pi in.


(Sandgroper) #10

If you killed a couple of SD cards as well as the Pi then you almist certainly connected 5Volts to the 3.3volts rail.


(Stephenb123) #11

Happy to report I replicated the setup and it’s now working without issue.

The only difference is that the adaptor I’m now using is capable of supplying highercurrent (the previous one was only 1A and therefore incapable of satisfactorally supplying both.) I’m still not sure if this could have caused the board to burn out but we’re into the realms of undefined beahviour here.