As I have way too much free time currently (I'm available if you'd like some help to tame a wild code base), I started a new clock project that is in the back of my mind since I reorganized my desk earlier this year.
The idea is to replace the word clock by a led matrix that could display time and fit on the shelf under the screen.
The gap between the two shelves is only 52mm. If I want to make it a full led matrix (that I could write text on), I'm going to need to go small on that one to fit the 11 lines required (to handle french accented letters :)
I was not sure the laser cutter (and the wood) could deliver on that size. So I cut some tests with different thickness between cells.
I was expecting the 0.8mm thick to fail (either being to fragile, or just burning). But it did not. And I'm really happy, this is quite promising.
My plan is to use ws2812b led in 2020 package (2x2mm).
They are ridiculously small. They're going to stress my soldering skills :)
This is quite compact pcb :)
Obivously freerouting did not successfully create a routing, but I can't really blame it.
I'll do it by hand tomorrow.
I ended making a smaller version, to lower the cost of a prototype I'm not completely confident I'll be able to build.
Also that version is symmetrical, I like it better :)
Next step in 3 weeks, when it'll come back from the manufacturer :)
pcb arrived \o/
Damn that's compact.
I knew it (I designed them) but seeing them is something else. That's way smaller than everything I've made before.
So, it's soldering time !
So this is an epic fail :)
The footprint I used for the leds does not match their actual layout.
By rotating the leds by 90°, they match the footprint's pinout so I was hoping I could still make it work.
But pads are too short and leds won't align correctly with them, so it fails :(
The good thing from this is that I'm quite confident I'll be able to solder them properly (once I'll get the proper footprint :).
Let's try again :)
Here we go again. With the correct layout this time (I hope :)
Pcb arrived this morning so I took the afternoon off to solder and play :)
Soldering went fine,, but I'm glad I invested in a small hot plate few months ago.
Apparently, only 1 faulty led, I have to fix.
I change the failing led, and some other but I still had some bad 'twinkling'.
I suspected (and hoped) the cause was bad leds as I had salvaged them from the previous prototype, they might have suffered.
So I solder another one with new leds, and no more twinkling. It works just fine!
(there is some brightness difference, but is because there is two kind of chips, the newer are brighter).
I'm really happy with this. I'm going to write some code to display stuff then It'll be time to think about the real version :)
I ended soldering the last pcb with leds from the same batch.
As expected, no more brightness discrepancy. It was worth it \o/
The code will wait :)
#LedMatrix #ws2182b #esp8266 #pcb
And we have clock ! \o/
This means I will most likely design the definitive pcb during the week end :)
I did not realize when I posted that the video was that bad (it was late).
So, I made a (I think) better one.
I think I'm done with this prototype, I'll start working one the bigger version, maybe 11x50.
The pcbs arrived this morning.
They're quite intimidating.
I have some other (paying:) work early afternoon then I'll be free to work on it.
Hopefully, I'll have it done for by the end of the day :)
First, I made a jig to align the pcb and the stencil reliably while applying the solder paste.
90 min later, half of the leds are in place. That's 324.
And 324 leds to go :)
Only an hour to finish the placing of the leds.
I'm getting better :)
It's ready for the soldering on the hot plate.
So I added a connector, plugged it to a controller and nothing happened.
I had a moment of doubt, maybe the whole thing was faulty.
Then I look closely at the first led of the chain, and one of the pin wasn't correctly soldered.
I fixed it, plugged it again, and boom ! \o/
I designed the case, but it's too late to start the laser cutter. It'll wait tomorrow.
Instead, I quickly adapted the code I wrote for the prototype :)
A case, and a piece of paper as a diffuser and looks so much better :)
I love it!
I still have some finishing touch, some features to code and a lot of cleaning :)
Antoine - Software therapist
Amélie