~ Glow ~

Week 9: Output Devices

ESP's and tiny traces are the bane of my existance

Closer Inspection

I was experienceing issues with how tiny the ADXL343 accelerometer was, and how the initial tracing and seperation setting in kicad made it difficult to route tracks. I did notice that Neil was able to make a track run through the little SMD package, and that the pads were as large as the traces. I managed to mpdfy the settings in kicad to allow for closer together traces and was able to keep using the 1/64" end mill rather than having to swap to an even smaller one.

I also noticed extra components (capacitors and resistors) on the example accelerometer board, which caught my interest. I was able to ctrl-F "capacitor" on the ADXL343 datasheet to find out why, and added them to my board as well. Thank Neil!

Investigated due to observing Neil's board.
Datasheet on accelerometer.

Back to the drawing board

Get it? Since routing a pcb is like *drawing* a **board**?
hahaha... Alright here's a re-do.
ESP32Accel-FrontTrace.png (Using 1/64 in end mill)
ESP32Accel-FrontHoles.png (Using 1/32 in end mill)
ESP32Accel-FrontOutline.png (Using 1/32 in end mill)
ESP32Accel-BackTrace.png (Using 1/64 in end mill

Final pcb routes
Routing is a lot more condensed

Milling

Milling went a lot smoother than before. The mods trick of pretending the end mill is .015 instead of .0156 helps a lot in ensuring everything is seperated. Otherwise I would have to come in with an exacto afterwards.
Another tip us to always take a picture of your origin point in case you have to reset the machine.
remembering my origin!
preview with the trick-mods-with-a-smaller-endmill tactic

Stuffing and Soldering

Was a mess. I think I shorted some of the ESP32 pins, and it would not accept code. Since I messed up my first board and was away from lab, I decided to scavange components to populate a new milled board (which I did have on hand).

I added an on-board LED for blink tests. Deciding the polarity of an LED was a bit tricky, but this site helped:
SMD LED polarity (https://lighthouseleds.com/blog/polarity-guide-of-0402-0603-0805-1206-and-most-all-smd-leds.html)
Alternatively, other say I could've used a multimeter
tiny components.
I had two boards and did indeed need to steal from one to populate the other.

Beautifully janky

It's a mess of a board, but it actually programs!
I gave it a neopixel example, and it lit up an adressable (meaning each "pixel" can be controlled individually) LED strip!

Another useful tool Anhad introduced me to:
https://falstad.com/circuit/ - A circuit simulator, to help understand and visualize what is going on.
I used it to look at things in my design, most notably the logic level converter, which I was so sure should have worked.

UPDATE: Turns out even though the theory and circuit does work, sourcing components was part of the issue since the mosfet I was using may not be fast enough to relay signals to the adressable LEDs.
finished.
On board LEDs look lovely
There they go.