Portability Shield screen issues

[bdavidson]

Hi, I’m setting up the RTK postcard and its associated portability shield. I have the shield attached to the postcard with a set of male and female headers. Is there some magic incantation needed to make the screen on the portability shield work? It doesn’t light up at all, and the “Test Screen” option in the serial config menu appears to have no effect either. The power LEDs and SD card appear to be working though.

When I probe the I2C positions on the headers with the boards separated, both SDA and SCL are successfully pulled up to 3.3V on each board. I used a spare ESP32 to scan the I2C bus on the shield only, and it detected devices at addresses 0x20, 0x36, and 0x3D.

Any ideas for further troubleshooting? I’m hesitant to attempt to remove the screen since the flex cable is soldered on.

[PaulZC]

Hi @bdavidson ,

Please check you are mounting the postcard and shield back-to-back. I made the mistake of mounting them front-to-back, and it had me scratching my head for a while…

I hope this helps,
Paul

[sparky]

I used a spare ESP32 to scan the I2C bus on the shield only, and it detected devices at addresses 0x20, 0x36, and 0x3D.

0x3D is the SSD1306 OLED Driver so it’s responding. Perhaps there is an interconnect issue as Paul points out.

[bdavidson]

I did mount the boards together correctly, they are helpfully designed with asymmetric header sizes .

I also checked for continuity between mating header pins (probed the solder joint on each board) and didn’t find any issues there.

[sparky]

Hmm, it’s possible it’s a bad display.

As one last check, can you compile/run the display test sketch? https://github.com/sparkfun/SparkFun_Portability_Shield/blob/main/Firmware/Example3_Display/Example3_Display.ino

[TS-Russell]

It looks like there might be some leftover flux or some other funky stuff going on with the headers’ soldered joints…do you mind taking a close & clear photo that shows them clearly (both sides)?

[bdavidson]

I tried running the display test sketch on an ESP32-Devkitc-v4 board as well as the postcard. Still a black screen. Here’s a sample of the output (with no battery connected):

15:35:25.922 -> OLED + Fuel gauge test
15:35:25.954 -> Begin success
15:35:25.990 -> Voltage: 4.09 V
15:35:25.990 -> Percentage: 102.56 %
15:35:25.990 -> 
15:35:26.973 -> Voltage: 4.16 V
15:35:26.973 -> Percentage: 102.56 %
15:35:26.973 -> 
15:35:27.239 -> Frame rate: 93.68
15:35:27.966 -> Voltage: 4.12 V
15:35:28.012 -> Percentage: 102.56 %
15:35:28.012 -> 

Photos of solder joints:

There’s a bit of flux residue and q-tip fiber strands on there, I tried cleaning it again. No change to the behavior of the screen though.

[sparky]

Something is up with the display. Please contact support for a replacement.

If you’re really savvy and or want to go down the DIY path (we’ll support you with a replacement regardless), you should be able to separate the display from the foam backing and view the solder joint between the OLED ribbon and PCB. Look for obvious shorts between pads.

[TS-Russell]

It also might be worth trying to re-solder these 3 pins; I am very suspicious of that dark brown spot between 5v and GND

[bdavidson]

Thanks for the help, I’ll get a support ticket going. I brushed off the brown crusty stuff (RMA flux residue) and reflowed those joints to no effect.

[bdavidson]

Quick update: Customer support is sending a new board, so I pulled up the screen to take a look at the connector. There was a microscopic piece of dark debris adhered between pins 3 and 4 of the screen connector. Scraping off the debris seems to have fixed it!

[PaulZC]

Hi @bdavidson ,

Many thanks for the update. Glad it’s finally working for you. Apologies for all the hassle. Please keep the extra board with our compliments.

Best wishes,
Paul