2/14/2026 7 PM - made the schematic

summary: the title, basically

background

this was my first time using kicad, but i've used easyeda to design pcbs before, but not ones that were so complicated

making the schematic

At first, the tools felt janky since I wasn’t familiar, but it got easier over time. I didn’t have too much trouble with the schematic itself, but the global labels were a little confusing at first. It was also weird not importing specific parts like in easyeda, instead using general placeholders (like 0402 100uF capacitors). The opening menu was kind of annoying since it took forever to load each time.

Keyboard shortcuts helped a lot—for like "a" to search parts, but it got confusing fast with others like “W” to draw wires. Overall, the process went faster than I expected. I double-checked everything at the end to make sure there weren’t mistakes.

Also, sometimes I just wasn't able to find the proper button, like when I was trying to turn my schematic into a pcb lol

Honestly, I think I did well. The only thing I’d do differently next time is copy more repetitive things, like each global label, and use more keyboard shortcuts to speed up the workflow.

footprints

so this was new to me - having to assign footprints manually. I followed the tutorial and it worked out fine, just new

2/14/2026 8 PM - the actual pcb

putting parts down

so after i got all the parts in properly from my schematic, the first thing i did was to follow the tutorial and make the board outline.
then, like in the tutorial, i aligned the large parts like the usb-c port and gpio pins

realization

finally, i made my first real design choice. in the tutorial, they changed their flash memory to a smaller version (both sizewise and memorywise). they also changed their LDO to a smaller footprint. I didn't see any problem with the LDO - since they had the same functionality. but with the memory, i thought to myself - "i would rather have 16mb of flash memory than 2mb."
-a beautiful quote by me

So, I changed the LDO to a small version, but I kept the large ass flash.
Now, this in itself introduced some new challenges. ts was like 4x as big as the old flash, so i had way less space up there. to mitigate this issue, i decided to shift the main RP2040 chip down more than it already was shifted by 1.5mm, which doesn't sound like a lot - but it is.

flash

anyways, i followed the tutorial, but routing the flash was a lot harder, since i wanted to avoid using vias for it was very high speed. anyways, i got it done, but the traces took up a lot of space
also: while i was doing this, kicad was being very annoying, not letting me route to the rp2040's traces. this was because the spacing was too near, so i changed it to use 0.1mm min spacing instead

usb

that worked, and i got back on track to routing
then, while i was routing the d+, d- traces, i had an awful realization: those two resistors didn't fit so i turned them on their side

clock

i wired the clock :) very nice and ez but i was afraid i would somehow wire it incorrectly so i like triple checked. also i tried to keep the traces very short

power stuff

Then, after the D+/D- traces, i moved on to wiring power, which wasn't too bad - in fact probably the easiest thing so far! - my only problem was to figure out how thick the traces should be. i settled on 0.4mm, which was more than enough probably and it fit fine so..

decoupling caps

then i started slapping decoupling capacitors onto the rp2040, which was probably the hardest fucking thing yo i could not fit any of those on for my life after adding that thick ass flash and so many traces
well after like a hour i wired them all up. i really dont know what else to write in this section except that it was fucking annoyng

gpio

so after that - it was time for the gpio pins
i take what i said about the decoupling caps back - the gpio was was way fucking worse
the bottom seciton was relatively easy since there wasn't much there, but the FATASS flash took up all the space, and on the right side of the rp2040 was the huge ass group of decoupling caps i couldn't get around, so i had to squeeze in like 100 vias to use the backside.

huge ass glob of decoupling caps on the right

fatass flash on the left

pain

and so i finished that shit, put in the ground pour,
then i was like: yo im done bro, i can get this in person
then i check the drc, and i get like 50 errors
and so i manually check them one by one to fix them - most of them honestly was just ground not being connected to it

but some of them were bad:

• so i just realized i had to connect all the 3v3 and 1v1 lines together outside the chip, which i didn't notice in the tutorial but kicad was screaming at me so that was very bad and took up all my space on the backside
• 1 missing 0.1uf decoupling capacitor no fucking clue where that goes - i deleted it from my schematic
  • more info: i'm 100% sure it was for a 3v3pin, i'm pretty sure it went on the top, but as i said before, my fat ass flash blocked it, so i doubled up on 3v3 pins (2 of them on 1 100nF cap) - bad but works ig
• a lot of random issues with silkscreen - to fix i deleted all unnessary silkscreen
• lots of unconnected ground issues - which is super annoying since i have barely any space to route, but i managed to resolve all of them - although some routes are hella chopped (*cough cough pin 8 on both sides)
• honestly after this i just spent a lot of time optimizing my pcb, like making sure d+/d- was length matched, as well as flash and, like route distance optimizations as well as some route thickness + part placements...

my own stuff

so as i said before, i'm using the large ass flash, not the small flash
also, i decided i wanted 2 onboard led's:

• one for power
• one for gpio25 that was unused.
• this didn't take long to wire and schematic

also i wrote up the silkscreen labels which helped looks a lot

FINAL 3D RENDER

2/15/2026 7 AM - more research

i was trying to find a few more things i could add onto my devboard

power

i did a lot of research on power ic's since i feel that the ldo rn is very inefficient and doens't have enough current capacity. also a little lcsc search shows that the ldo is 1 whole dollar is is out of stock so i will have to find an alternative anyways. rn after a lot of research, i'm thinking on the TI TPS63070RNMR - 1.2dollars or the RT6150 (60 centsthe one the pi pico uses), it requires a lot of external components and space i don't have

one thing is fs: i definitely need a larger power supply since this one is only 250mA, i probably need upwards of 500

silkscreen

this one took forever, i just could not, for the life of me, figure out how to put a silkscreen on with the image thing, since the footprints were very confusing. then i had to figure out how to scale it, which took so much time

2/15/2026 2 PM - battery support

battery support

so i wanted my pico to have at least a little support for battery, so i took a look at the official pico datasheet.
i realized that i had to give up at least 1 pin for battery input
easy choice, screw adc3
i replaced that pin with VBAT, which will take in input from battery, then send it through a schotkey diode, which will OR with another schotkey diode from the usb, so that if both are plugged in, nothing bad will happen.

awful importing

so there was no footprint for the part i needed to use (FUXINSEMI FMBR120VLSFT1G). that meant i had to import it myself. i had 0 clue how to, and after doing tons of research, i found the impart plugin which could download stuff from easyEDA. this seemed perfect, but i could just not get it to work. it took a good 2 hours of my life to try and set it up and configure it before i could even download 1 model.
after that, it was much easier, and i was able to download the footprint + 3d model of the diode (as sell as the new ldo)

repurposing the adc3

Now, i didn't want to just "waste" the adc3, so i made the read the internal vsys voltage (after the diodes, before the ldo. I used a resistor divider system i found in the pico datasheet to lower voltage by 3x so that voltages up to 9.9v will work (i'm still considering whether i should switch it to a ratio).

Note: after further research, to support the full 18V of the LDO, the values will have to 470kOhm and 100kohm, but it's probably worthless since there is just far too much heat, so i'm capping it at 9.9v

better ldo + research

Then, I also decided to switch the LDO to a more powerful version that supports up to 500mA and 18V (TPSPX3819M5-L-3-3). I was also researchign a lot of buck boost converters (TPMP1470GJ-Z) but they were just too complicated for me.

2/15/2026 7 PM - reset button

reset button

i wanted to use 100% of the space in the board so i added a reset button
its really simple, it just pulls the reset pin to gnd when the button is down

in the pcb, i had to move it to the very bottom, where there was the last bit of space left, and i had to move quite a few gpio wires for this, which was very annoying
i also moved my logo silkscreen off to the side for this though

vsys pad

also, without an exposed vsys, i just made a small pad just for testing.

2/15/2026 8 PM - final product

i dont see what else i can add to this board that would be useful to "most" people, so I'm going to leave it here.

Of course, I can't just leave it here, so I'm going to add some more art to the bland backside.
And of course, I spent a good hour labelling each pin and painstakingly aligning them

I'm very happy about how this turned out, and I've used almost all of the board to its full potential

Final product (back):

Final product (front):

pcb

side note i put everything i did onto github - the images, gerbers, the 3d files, as well as all the manufacturing files

future steps:

• buck boost power input - this would reduce heat significantly and allow a much wider range of power
• exposed vsys - would just be nice i guess
• 3v3_en - useful for low power applications

3/10/2026 12:05 PM - got the parts + testing

today morning the parts got here!!

the first thing i did was plug them in, and I saw the power LED light up, and guess what, IT EVEN OPENED THE BOOTLOADER first try!!

so I uploaded the firmware on the github, AND IT WORKED! like the day was going so great!!
then i had to figure out how to use circuitpython, but it wasn't that hard, and after editing code.py with my blinky code, it worked (first try too!!)

then i tried to read the ADC3 (internal vsys voltage) that i added to the board.
at this point in time, i realized that i had no clue how to see the serial monitor.

i tried to download circuitpython on vscode, but whenever i tried to open the serial monitor, it would error out. i was trying to make this work for so long, like an hour even, but i couldn't get it.
but i still managed to get it to work by opening up arduino ide, and the serial monitor would read the right voltages.
and guess what the internal resistor divider worked! it read 4.9v from the usb!!
i even checked the built in cpu temp, and it worked great too.

then i tested the reset button, and it worked perfectly. even the bootsel button works!!

i was checking the ldo to make sure it wasn't getting too hot, and it seems fine :)

after additional testing, i even managed to confirm that there was 16 MB of space being recognized !! (15310.0 KB)

I even overclocked it and it worked fine :)

Blinky picture:

3/10/2026 12:06 PM - soldering headers

and it was going so great, so i began to solder on the headers.

for the first board, i was soldering it, but one of the headers came out a bit tilted :(. also, i realized i used wayy to much solder
oh well, not a big deal

after soldering the first board, i went to go flash the second board, but without looking, i set my fucking hand down on the fucking iron and that shit stung but whatever

so for the second board, i put the headers completely in the breadboard before soldering it, and tried to use less solder, but it was still a bit too much.

GP0 blinky (on board #2) w/ soldered headers: