Cool ! I soldered one of these connectors by hand but then I used the hot plate as it was too messy by hand.
I had trouble with the buttons, they needed to be quite perfectly aligned with the PCBÂ border (footprint has been fixed in a recent commit), and they were not on my boards, so they were constantly pushed by the case buttons. When fixing this I lifted a pad of the button from the PCB, but then it was fine with scraping the trace and soldering there.
Ahh yes, unfortunately our FFC connector did go EOL after the first production batch. The footprint is pretty straightforward so fingers crossed you can still find a good part for it. Latest commit in the Tangara hardware repo does use a new (very similar) connector, but obviously this is not much help if you've already got boards made.
Our main approach for hand soldering those FFC connectors has been to use a hotplate for the bulk of the work, then check for any pins that aren't bonded properly and fix them up individually with an iron and a ton of flux. They're a bit of a fuck, but it is doable! And it looks like you're doing really well so far! Best of luck with the rest of the work.
2025-01-24, 09:25 PM (Edited 2025-01-24, 11:40 PM by vurpo.)
It lives! The screens I ordered are taking their sweet time getting here, but by all accounts it looks as if I have a functioning mainboard! I ended up doing a new PCB and just trying the FFC connectors again until I got the hang of it, and I think the mainboard and faceplate are all correctly soldered now.
edit: it plays music successfully, so everything seems good now save for the missing screen!
So I got the screens I ordered and soldered one on, and it works correctly (responding to volume buttons and everything) except for a strip of pixels 1 px along the right edge and 2 px along the bottom edge that appear glitched somehow.
Then I also noticed the touch wheel does not respond, and when inspecting the solder joints, I noticed my touch controller chip is entirely missing pin 10 on the package? If that pin is supposed to be there, then I assume this is the reason the wheel didn't work.
For the small corrupted-looking border, you most likely just have a display with slightly more pixels than the displays we ship. There is some small variance in this specific kind of display! To fix the issue, you can flash a dev build with this line uncommented: https://codeberg.org/cool-tech-zone/tang...m.cpp#L344 Note that your device's screen size is stored in NVS, so once you've flashed such a build once you should be able to return to mainline firmware releases without any ongoing issues.
That missing pin 10 is wild, we've never seen that before! That pin switches the IC from I2C-configured mode to a weird preconfigured 'standalone' mode so it makes complete sense that it not being attached causes issues with touch input.
So when looking closer I noticed the display does have the correct amount of rows and columns, but it was drawing shifted a few pixels up and to the left. From what I read online, ST7735 clones do this sometimes? Anyway as a proof of concept bodge, I got the display shifted into the correct position just by adding 1 and 2 to x1, x2, y1, and y2 here: https://codeberg.org/cool-tech-zone/tang...#L312-L318 but I'm sure there would be a "cleaner" way to do it if correctly supporting clone display drivers was a priority.
