LED Matrix Controller

Despite appearances this project is not dead! I managed to assemble a complete board on about my fourth attempt!

This time I used a reflow oven and paste - I still had a few blobs to deal with but it was quite a bit easier!

Now I just have a lot of software to write and debug to get it working! It looks like the timing might be a bit off on the display driving code - some rows are brighter than others. I’m hoping this board might actually be powerful enough to use a timer rather than a loop which should make things more consistent.

After some poking around it was sort of working - not entirely surprising since the timing for driving these displays is quite tricky sometimes.

Unfortunately that questionable soldering did turn out to be a problem on some pins - while I think I’m getting the hang of soldering these things now, I’d bent some pins and while I did try to straighten them, it just made more mess and lifted a couple of tracks.

The good news though is that I have enough of a board to try out some other ideas on, and I should be able to assemble one more board properly now I’ve learnt what to avoid!

The STM32F407ZET6 parts come packaged telling you to use a vacuum pen to remove them and they’re fragile - they aren’t kidding about this! I got a cheap vacuum pen from Amazon and from playing around a bit it should make it far easier to not bend pins. 

I’ll get there eventually! 

The last rework attempt - while not entirely successful - did work fairly well until I spotted the bent pins.

after my previous failure to solder down the micro controller correctly, I bought a couple of slightly cheaper ones (I didn’t need all the power in the original anyway) and tried again. After some careful work it seems to turn on!

• I can connect via an STLink v2 interface and openocd 
• I can toggle a pin on and off
• I can connect via USB in DFU mode

I need to write more software to properly put it through its paces, but so far so good - despite the soldering looking a bit questionable in places!

As to where I went wrong last time, I think the answer is too much solder and not enough patience!

After sitting around for months I finally got around to attempting to solder up a board. It was going quite well until I made a complete mess of the qfp-144 stm32f417 which turned into a mess of solder blobs I couldn’t shift. I’m not sure if my iron wasn’t transferring heat properly or I just suck at it, but attempting to drag solder it just didn’t work out - maybe it was because I was using lead free solder but the blob stuck to the first pins and wouldn’t move down as I dragged the iron over it. Anyway I have some breakout boards for smaller parts of a similar pitch on the way and I will try again on those first before trying the led matrix board again