Hung-Chi Wang

Rendered this beautiful demo!!!
Cuz the PCB itself is actually kinda chopped so I gotta rendered this demo myself lol
On top of that I also published the files to github hope you guys like it

Spent some time doing the following:

• Added a pull-up resistor for PSYNC
• Added TP pad for PGOOD
• Ran DRC, fixed the pinheader connector
• Ordered the board
  *** btw I gained this time yesterday but I was just too busy to devlog

Just spent an hour doing the following

• Added TP pads (just in case RT6154AGQW fails again)
• Somehow managed to prevent the copper island
• Ordered the board after cleaning up DRC

FINALLY FINISHED ROUTING + DRC CHECK!!
I also rendered this to showcase lol
Routing this time was kinda easy and I really love how straightforward the hardware is, but I think the challenge might be mainly the software side DAMN

Almost finished routing everything!!! This was actually much easier than I thought, might because there were barely any peripherals except the SPI
I alos replaced replaced the buttons to the one i used for the tic tac toe business card, hope it works better lol

Spent almost an hour and a half routing the RP2040 cluster
This time was pretty easy cuz there’s barely any peripherals to route, and the main focus is definitely the screen connector rather than anything else

Spent an hour organizing the crystal cluster cuz it looked kinda ugly and too close to each other which made them kinda hard to solder……anyways here’s the new result

After the failure, just in case it’s bc of any design issue here’s a couple changes I made:

• Removed RUN by simply crossing it out
• Replaced 10uF cap for AP62401WU with ceramic cap
• Removed PSYNC as it occupies GPOI23 and I just wanna get it work so bascially removed some complexity
• Added a couple TP pads just to make sure i wont blow anything up again when testing lol

Just a couple things I did

• Finalized the schematic
• Positioned the PCB
• Designed the card size

GUYSSS I finally got my boards and gave the very first shot!
I gotta be honest popularizing the board is the most boring process, and it took me almost 1 and a half hour……And after spending almost one more hour of repairing I FAILED TRAGICALLY
But anyway here’s the result (look at the picture below
***Note that the hours were recorded the day before but now I finally have time to devlog

Updated my readme and release and ready to ship for the new system!! (btw i just realized that I forgot to post devlog after getting this 1 hour so don be surprised by how I get this hour so fast

Spent some time updating readme and release!!
This is really the best project i’ve ever made, even though it might look a little intimidating!!!!
*** Btw i also rendered this, and this is exactly how the final product will look like

Finished and ordered my custom radio module!

• Cleaned up DRC (pls ignore lots of clearance issues as it was simply bc of the custom antenna
• Sorted out BOM
• Added tons of vias
• Removed solder mask (acc i wanted to test out both with and without solder mask
• Submitted my order
• Rendered the custom board

Spent some time on routing the my radio PCB, checking DRC, and re-arranging the layout
*** Damnn I just realized that I shouldn’t switch 0402 components to 0603 cuz the radio might somehow be detuned……..

Alr just created the bom file and added everything to the cart
Btw I also decided to include all color LEDs just in case lol
On top of that, I also sorted all the parts for my RP2040 custom devboard

3 hours!? DAMNN lapse was kinda tripping when I was working and I thouht it was only 45 minutes……..(no wonder why it felt like forever :)
Anyways here’s what I did

• Reread the document for the NFC chip and realized that a 220nF cap is required
• Polished the PCB layout. including replacing 0.1uF with 1uF for 3V3 and 1V1
• Updated Readme and Created new release
• Re-rendered the new front layer pcb
• Ordered PCB

Time to order the PCB!
This time I decided to print the board double sided, while making the stencils as small as possible
Something i noticed was that top&bottom stencils didnt acc cost more than single only top so why nott
On top of that, I also added all the components to my cart and they’re now ready to order!

Here’s wat I did for the past 1.5 hours

• Updated README and Release
• Rerendered PCB
• Cleaned up DRC and replaced 0.1 uF with 1 uF for 3V3 and 1V1 according to RP2040 hardware design
• Added more vias

Alr finally routing everything. Time to do some clean up and ready to order the gerber!!

• RP2040 cluster
• SD card
• Screen pin holes
• Including all buttons from the original gameboy

Almost done routing the PCB!! Now I only have 10 traces left
*** I also removed RUN cuz I don really mind unplugging the game console lol

Finished routing for the following parts:

• Flash Storage
• Power Supply
• Buttons (except the start and select)
• SD cards

Finished prototyping using my RP2040 custom devboard!!!
This basically validates my design for the PCB as it uses the exact same parts except different PWM pins
*** Note that I haven’t added nrf24l01 in my design as radio is very unpredicatable

Huge progress!! Here’s what i did in the past two hours

• Positioned most parts (except some resistors and capacitors)
• Removed Bootsel and reset buttons with a connector
• Added pull-up resistors and caps

YAYYYYYY this time I prototyped on my RP2040 devboard and DRV8833 even tho I gotta use an Arduino Uno for power supply. I tried to power L298N from my custom board but it didn’t work cuz the current spikes are crazyyyyy. But anyways huge success, next up imma connect it to my radio nrf24l01 and see how it goes

Roughly finished the schematic

• RP2040 (no need GPIO)
• USB-C plug
• Crystal 12MHz
• 2MB flash storage (it’s enough ig)
• MCP73871 (battery charger)

DAMNNN spent so much time on fixing this island…….I tried my best but still had to compromise many traces for the big flash storage

Just added some personal touch

• Added back silkscreen
• Picked purple as the main color
• Began picking up parts from LCSC
  *** Im really trying my best to polish this as much as possible lol

Alr time to wrap this up, I cleaned up all the routing and here were some changes i made:

• Moved the diode to the top right corner instead of clamping with the power regulator
• Moved as many routes to the front as possible to keep the back copper as clean as possible
• Added thicker traces 0.5mm
• Removed two islands on the back copper (it’s sacred!!!)
• Cleaned up the DRC once again

Finally finished routing the entire board and cleaned up the DRC!!
***Imma just add some more final touch before ordering the boards (like cleaning up the silkscreen

Here are some of the things I noticed

• An unwanted island on the back (directly under the flash storage)
• Unconnected GND due to very tight layout
  *** BTW I kinda regret of not switching to 4-layer board…..DAMNNN (but it’s also more expensive so we’ll see lol

Well well well guys this is getting frustrating, how in the world does my SD card module doens’t match those on github………HOWWWWWWW

Just finished routing the RP2040 and most of the stuff!!
** There really isnt too much abt routing just trial and errors ig

Assigned footprints and began routing the PCB!!!
Since this is the very first prototype, I’ll use the screen module and very simple buttons
Btw I also decided to use the 16MB flash storage! Why? Just in case lol

Finished routing the left area, btw I also applied what Ive learned for the past few weeks

• Boot button can easily be routed to a long trace cuz it has very low frequency
• Added tons of wide traces to 3V3 (like 0.5mm if possible or else 0.3mm)
  I mean it’s routing dont really have anything to say lol

Completed routing flash storage and 1uF caps

• The two 1uF caps need to be very close to pin 44 and 45
• This flash storage is much larger than the original one (but it has 4x more storage sooooo :)
• Increased the width of the data lines (idk i heard it’s better lol

Finished routing the power supply parts!!! It was acc much smoother than I thought cuz of the layout ig

AHHHHHHH this is getting kinda frustrating……….
Now I have two options for the charging IC

• MCP73831 (fits better but then I gotta deal with unwanted dicharging and battery protection)
• MCP73871 (very overkill, very unnecessary)

Selected the battery and its associated parts:

• MCP73831 (the charging IC)
• LIR2450 (the battery)
• Keystone 3008 (battery holder)
  *** Still looking for battery protection IC

Assigned footprints (replaced many 0402 with 0603 and 0805) and roughly placed the layout

Completed the schematic!!!
Updated areas:

• Replaced W25Q16JVUXIQ (2MB) with W25Q64JVXGIQ (8MB a huge upgrade :)
• Replaced MCP1700x-330xxTT (linear regulator) with RT6154AGQW (buck converter much more efficient)
• Added Schottky Diode to allow external power supply
• Added a RESET button
• Changed 33pF crystal cap to 15pF to match the crystal I ordered
  Now my custom devboard will become much more powerful and resilient

Routed everything and added some final touch!!

Huge success!!! I finally made two custom RP2040 boards communicate with each other through nrf24l01, and next up imma wires them to my custom board

Just tested out the transmitter, while testing out my RP2040 custom devboard!!! (huge success)
Pins:

• CSN: GP12
• MOSI: GP7
• CE: GP11
• SCK: GP6
• MISO: GP4

Finally finished the schematic!!! Here’s some changes I made

• Upgraded flash storage from 2MB to 16MB
• Pull-up every pin for SD card
• Removed external power-supply cluster
  *** Note that I’ll add battery in V2 but for now let’s just focus on the core functionality

Tested out circuits on Arduino UNO + L298N first!!! Imma try out RP2040 and TB6612 later

Spent some time soldering all the components for prototyping

• RP2040 board (I made it myself!!! :)
• nrf24l01
• TB6612

DAMNNNN I just picked all the parts manually……guys MANUALLY
IT TOOK ME SO MUCH TIME (look at the price :( SO EXPENSIVE
*** BTW I also discovered how I accidentally used 0603 for a 10uF cap, but we got solutions lol

Working on SD schematic and learning SD to SPI translation so that my RP2040 could read games from SD card
*** I didn’t even know there was translation between SD and SPI, so I spent so much time figuring out

Roughly finished the schematic for the game boy console!!!

• RP2040
• USB-C + RT6154AGQW
• LCD Screen

Added NFC feature and imported the footprints!!!

Roughly finished the schematic!!!

• RP2040 cluster
• NFC
• E-paper Screen
• nrf24l01 (not added yet

DAMNNNNNNNN I MESSED UP THE SCHEMATIC!!!! SO I gotta spend the past hour rerouting everything especially for some reason my schematic and PCB layout disconnected :(
Anyway here’s the final result!!!

Completed the routing for the screen module!!! btw I also rendered this

Assigned footprint (and fixed some capacitor issues :) and let’s get start routing our first screen module!!!

YAyyyyyy this time the layout isn’t too bad lol
Just spent an hour figuring out the layout and trying to connect everything

Damn I kinda messed up the reference number and the parts………I didn’t know that I needed to use 0402 lol
Anyways we can finally get into PCB layout and routing!!!

OOOOOOOO finally got to the most exciting part cuz guys radio is very sensitive to any changes!!!
But anyways WE GOT THIS lol
Btw i also picked the cyrstal (YXC Crystal Oscillators X49SD16MSD2SC) from LCSC let’s hope it works

Finished the schematic for the custom nRF24L01 module!!! YAYYYYY

DAMNNNNN easyeda cannot export to kicad for some reason………So I gotta draw a new one myself. Anyways after spending some time here’s the beautiful result

Finally copied RF antenna from the datasheet!!! It was kinda a hassle lol

Spent an hour on designing the schematic for the radio!! Im going build radio module first

Here’s a couple things I changed before moving on to nrf24l01 radio

• Changed 0603 47uF capacitors to 1206 so that it can handle 25V spikes
• Rerouted everything around the two capacitors
• Double checked the schematic and cleaned up the layout

After struggling for 2 hours, finally replaced the two inductors with 4mm x 4mm one!!!
*** You’ll see how much I struggled in lapse lol

NOOOOOOOOO I just noticed that I picked the wrong inductors……….I accidentally picked the 0201 one and that doenst allow enough current (like nowhere close)
*** Look at the highlighted part

Let’s begin our journey towards the chess card!! Well first of all the most important thing here is the screen

• Drew the schematic for the screen module
• Imported symbols from EasyEDA
• Picked FPC-05FB-24PH20

Spent almost an hour updating Readme and planning out V2!!!
Here are some improvements im going to make:

• Larger flash storage (16mb preferably)
• Add two Schottky Diode to allow external power supply
• Replace the original voltage regulator with RT6154AGQW
• Add a reset button
• Increase the resistance of LEDs (my eyes bruh
  *** Look at the highlighted parts and btw I also decided to REROUTE EVERYTHING

WOOOO I spent so much time on fixing and rerouting AP62401WU……

• Added a Schottky diode to prevent current from leaking back feeding to AP62401WU
• Changed the placements of AP62401WU output capacitors as they may generate tons of voltage ripples and malfunction other delicate ICs (look at the highlighted components)

Tested out my XOR gate (the first version) but unfortunately it didn’t work as well as expected

• 4.7k ohm for base resistors
• 1k ohm for pull-up
  *** I did this 2 days ago but I just forgot to log it

Here’s the video demo of my working macropad

After 2 hours of struggle, finally FINISHED THE PROTOTYPE

• SDcard breakout module is now connected and running (I stored Pokemon red version)
• Screen can now display what is inside the sd card
• Users can now press button A (GPIO 7) to enter the game

Tested out all the functions, updated repo/README and rendered this

• Added a professional Release page
• Formatted my README in the way how I did for all the other projects
  *** Btw dont be surprise how I got these 2 hours right after my previous devlog (simply cuz I forgot to log this a month ago lol

the image in the previous devlog is not showing, but it’s fine after doing some tuning and modification to the NFC here’s the beautiful result
*** IDK why the images in the last devlog aren’t showing

Added some design to the front silkscreen!! And I also rendered the board in blender

I spent an hour fixing the NFC and I finally found out the reason!! I FORGOT TO CONNECT THE OTHER ROUTE, that’s simply why lol

GUESS WHAT I began to build V2!!!
This is what im gonna be focusing on

• Fix NFC feature
• Add coin cell battery
• Better Design on both front and back
  btw I spent an hour doing research on how to add battery and learning figma lol

Well well well for the past two hours I was designing my nrf24l01 antenna and trying to implement it into my design
I thought I couldve just imported other people’s designs but HELL NAH
Here are a couple options that I can refer to tho

• AN043
• AN2731
• AN91445
  But ofc i lean towards the first one and im probly gonna copy that too lol

Alr last devlog before ordering!!
Double checked everything including adding more vias and ran DRC twice
One last glance at my beautiful PCB :)

Updated README and added a release!! Btw I also added a little sketch fab model

Rendered my PCB!!! And also made this blueprint style image (see the second image)!!!

I spent some time on reading RP2040’s datasheet again and learned that there’s only two SPI and I2C engines, with 8 slices of PMW

• Read RP2040’s datasheet
• Fixed PMWA and PMWB routing
• Rerouted USB-C cuz I decided to swap it with the 01x04 pin header
  **Now you can see all the parts beside USB-C are rerouted and USB-C is also moved to the top-right corner

Here’s wat i did for the past two hours

• Added a 100uF polarized capacitor to prevent 12V spikes
• Rerouted the 12V connection part AGAIN OMGGG
• Edited RT6154AGQW footprint
• Cleaned up DRC errors

Finally finished routing!!!

• Rerouted “EVERYTHING” for the two voltage converters (you can see it in my lapse
• Reassigned PWMB to GPIO27 so that I could add some more vias
• Routed everything and cleaned up the silkscreen

OMG this is getting frustrated!!! I really should’ve used 4 layer board lol
Cuz now Im having two troubles

• Some GND pins are still unconnected
• There are two pins far apart……but they are blocked by traces from MCU DAMN

After two and a half hour of hard work, I almost finished the routing!!!!

• 0.18mm
• 0.20mm
• 0.30mm
• 0.50mm
• 1.00mm
  There’s really nothing to say about this process, it’s just fun lol

Spent some time roughly wiring up the screen tho it doesn’t work somehow (probly cuz i haven’t soldered my pins

Ok so I finalized my schematic after postponing for a month particularly cuz got a little lazy
Next up imma start routing the full-adder and order it
I also tested out all different cases to make sure I get it right the first shot

I roughly positioned all the main components and changed the number of output pins to allocate for GND and 3V3

• Motor driver at the front, far away from RP2040 chip
• 45mm x 45mm dimension
  *** I would still need to change the order of pin headers to reduce intersections as much as possible

Connected to footprints!!

COMPLETED THE SCHEMATIC!!!! FINALLYYYYY
I tried to make the PCB in a square shape lol
Btw this only includes RP2040 and TB6612FNG motor driver, I’ll add nrf24l01 later

Completed the schematic for AP62401 (12V to 5V) and TBTB6612FNG!!!
Damn and I just realized that TBTB6612FNG is actually the chip itself lol
Any way here’s a little diagram explaining how the power supply works:
12V –> AP62401 (12V to 5V) –> RT6154AGQW (5V to 3V3) –> MCU
–> TBTB6612FNG –> Motors

Spent some time on finding voltage regulator to convert 12V to 5V so that battery can also supply RP2040 (ofc not directly

• Learned and decided to use AP62401
• Created symbol and footprint for AP62401 by referring to the datasheet
  Link to the datasheet: https://www.diodes.com/datasheet/download/AP62400.pdf

I was figuring out how to wire the RT6150AGQW

• Pico schematic uses RT6150B-33GQW but apparently no one is selling it or it’s too expensive
• Ricktek only shows the minimal design so I have to figure the math
  R1 = R2*(Vout/Vfb - 1)
• Imported symbol and footprint for both RT6150AGQW and MBR120VLSFT1G
• Fixed the symbol to stay organized

I roughly completed my schematic while referring to pico schematic
Here are sth I noticed:

• Should use RT6154A instead of MCP1700x-330xxTT for larger current
• Add schottky diodes if external power supply is needed
• Connect GPIO24 and 23 to RT6154A to monitor whether the board is either using battery or USB to switch between PWM and power saving mode

V1 finally done, just spent some time updating my repo and posting the first release!
I also planned out the V2:

• Fix NFC feature, probly redraw the antenna ig
• Add a reset button
• Add a battery
• Add silkscreen, mask design with all my information just like a proper business card
  Just one last glance at my beautiful MCU :)

FINALLY DONE!!!!! I finished the game logic and flashing animation when either of the player won or a tie happened!!

Instruction

• Player 1 is orange, and player 2 is red
• Press left to move to the next grid
• Press right to select the grid
• Just like any tic-tac-toe rules

Well I changed the routing a little bit and removed two capacitors cuz they were kinda in the way and not very important
Anyway I think this might be the last devlog

OMG I just worked 3 hours on this and my tic-tac-toe card and im now just devlogging this after I did for the card

• Created git release
• Rerendered 3D model (this one looks better trust)
• Upload the model to sketchfab
• Added some final touch to my README

For the past two hours I finally made the control system work!!!!

• Press left button for next
• Press right button to select
• The pointer will automatically skip the selected grid
• The pointer will go back to the first grid if it reaches the last grid

• Rendered keyboard using blender
• Watched tutorials on how to simulate metallic textures
• Configured new preferences
• Exported STL using fusion 360
• Learned how to resize file through FBX
  The rendered keyboard is gorgeous!!! Btw the cherry keys are actually not metallic but it looks nice in the render so imma keep it lol

HUGE SUCCESS, I finally got the board and everything except the NFC seems to be working perfectly!!!

• Tested out all the LEDs
• Installed Micropython
• Installed Thonny
• Coded left and right buttons
• Watched Micropython Tutorials

For the past two hours I was learning how to render my PCB board
ik it might not sound very important, but it looks extremely cool!

• Installed pcb2blender
• Watched tutorials
• Imported new models for my USB port
  *** I didn’t even know how to use blender and I learned it along the way

I spent some time testing out all the pins!!! AND THEY ALL WORKED PERFECTLY!!!

• Installed Circuitpython
• Tested out all the pins
• Used multimeter to make sure everything works

I spent some time on soldering the logic gates, including AND, OR, NAND, and NOR gates. However, because I forgot to cut the wires before turning them on, I accidentally burnt the OR and NOR gates……DAMN
Overall, the AND and NAND gates worked pretty well:

• 10k resistors for the base
• Diodes to prevent current from leaking

Learned how to code and access RP2040 processor using XIAO-RP2040 (haven’t yet received the board yet so…….)
Tutorial I followed: https://www.youtube.com/watch?v=07vG-_CcDG0&list=PLWNDWPAClRVoo0Z-QtCkXuM15jdb2Q54N&t=820s

• Installed Thony IDE (originally I was planning to use Micropython
• Swtiched to Circuitpython so that I could use VScode
• Trouble-shot Circuitpython extension (it sucks and I gave up)
• Eventually I noticed that I could simply use serial monitor in vscode (check out my lapse)

Check out the video!! https://hc-cdn.hel1.your-objectstorage.com/s/v3/4d0905c78ba392b4_img_0659.mp4

Here’s what I did for the past two hours:

• Excluded NFC from the copper pour
• Redesigned NFC Antenna
• Chose all the parts and edited BOM file, I repackaged everything thrice
• Triple-checked the 3D viewer
• Tried my best to replaced extended components with basic

PS: it’s 70 USD (89 CAD when I checked my bank account)!!!! SO I SPENT SO MUCH TIME ON CHECKING TO MAKE SURE EVERYTHING GOES RIGHT

• Added silkscreen design to my PCB, including my logo and name
• Chose parts for JLCPCBA (spent so much time on avoiding extended parts…….
• Fixed the 3D model in PCBA viewer (SOOOO IMPORTANT OMG look from image 2 to 3
• Rerouted GPIO24, RUN, and GPIO 25
• Swapped the positions of 3V3 and 1V1 capcitors

I soldered the keys and the board!!!
But for some reason it’s still not working, apparently my Arduino Micro has some issues too cuz it kept disconnecting itself when tried to flash it……

For the past two hours I was trying to add NFC feature to this card!!!

For the past hour I was cleaning up everything, including:

• Swapping 1V1 capacitors with 3V3 (I mean the position) cuz 1V1 is crucial for chip logic supply and more delicate I suppose
• Adding more GND vias
• Rerouting a couple wires to the LEDs to allocate more space for NFC
• Cleaning up references
• Cleaning up DRC warnings and 2 errors

Finished routing everything!!!

• Rearranged the pins
• Added tons of GND vias as usual
• Aligned USB socket with the edge

Almost done wiring the IC components!!! YAYYY
PS: I deleted to capacitors as there are two pairs of 3V3 pins very close to each other

• Finished tic-tac-toe grid positioning
• Replaced 0402 with 0805
• Researching alternative flash storage (the original one is too big)

Roughly positioned the components, mainly searching parts on JLCPCB cuz extended parts are too expensive…….

Completed the schematic and footprints!!!
Part Selections:

• 0402 Capacitors
• 0402 Resistors
• 0402 LEDs
• RP2040
• ABM8-272-T3 12MHZ Crystal (recommended by the official)
• W25Q128JVS Flash Storage
• USB-C

Time to test out all my logic gates!!! For the past hour I was learning how to use V-Cut for my PCBs as they’re all very small so it’s not very wise to put them all on separate boards. Merging AND and OR gates is kinda tedious tbh

Here’s what I did for the past one and a half hours:

• Learned and implemented another type of XOR gate (*This is better as one input can now supply one transistor instead of two)
• Designed isolated AND gate schematic
• Designed isolated OR gate schematic
• Simulated ALU (Adder + Subtractor)

• This time I included base resistors for all the transistors

I spent one and a half hours trying to figure out Subtractor and complete the entire ALU………BUT KICAD is acting so weird……..
4-bit adder acts perfectly but for some reason subtractor just doesn’t want to listen……..AHHHHHHHHH

I moved all the complex circuit into a sub sheet!!! Now it’s officially called the 4-bit adder!!!
BTW I also recorded a little video here:
https://hc-cdn.hel1.your-objectstorage.com/s/v3/226f3b5086f14841_2025-12-31_21-21-35.mkv

(Troubleshooting) GUYS MY 4-BIT ADDER WORKS PERFECTLY!!!!!! Especially after I added buffers to each split!!!! W buffers
Btw I was fixing my 4-bit adder for the whole time cuz apparently Kicad spice doesn’t really recognize GND, so instead you gotta use 0V instead

I spent two hours and a little more learning negative numbers (subtraction) and SR latch (can be easily turned into D latch)
Lemme briefly explain why they’re important

• Negative number (subtraction): I mean obviously subtraction is important lmao…….
• SR latch/ D latch: SR is the acronym of Set and Reset, Set sets the state to 1 while Reset restores the state to 0. And this property can be used to store data!!!

BTW the image only shows how subtractor works, but i promise i’ll be demonstrating through videos of how registers work!!!

Here’s the steps to convert a positive number to a negative number

• Step 1: Invert all the digits (e.g. 7 represented by 0111 becomes 1000)
• Step 2: Add one to the inverse (e.g. 1000 + 1 = 1001)
  AND BOOOM 1001 represents -7, just look at the image

Finished routing the PCB!!! OMG I really really can’t believe how compact this can be……..Cuz it’s so tiny compared to the prototype on breadboards!!!!!!

PS: This is a Full Adder btw

For the past one and a half hour I have been building a 4-bit adder…….but fan-out is definitely my enemy!!!!
As you can see the 5V drops to 4.53V bc of the transistors!!! I was trying to implement two inverters at the end but still didn’t help…….

I finally found out the issue!!!
The issue was that I forgot to add resistors to the base of each transistor. I only added resistors directly after A, B, and Cin, but the bases of transistors in each sheet don’t have their own resistors, so that’s a big issue as they will burn out.

W Resistors :)

Fixed and tested out all the truth tables for my schematic, and not all of them worked……
Even though it seemed like only one of them didn’t work (the one with only Cin on), but for some reason no current was passing through one of the transistors in the XOR gate!!!

SO I gotta spend some time investigate……

PS: All the images are different cases even though they look similar!

YOOO I DIDN’T KNOW KICAD CAN SIMULATE CIRCUITS!!!!!! BIG SUCCESS GUYS
Here’s the truth table I tested out (Input 1, Input 2, Output):

• AND: (0, 0, 0), (1, 0, 0), (0, 0, 1), (1, 1, 1)
• XOR: (0, 0, 0), (1, 0, 1), (0, 1, 1), (1, 1, 0)

W KICAD!!! GUYS btw if you want the spice models for 2N3904:

• 2N3904: https://drive.google.com/file/d/1D6OUzF6kyITwRnlAD-tuOaJGhS3EWNvB/view

I just noticed that I forgot to save the latest version of my PCB design………!!! So I spent a little time fixing them, including adding vias and running DRC to make sure everything works out fine

W DRC :)

Completed the FULL ADDER schematic!!!!!! Btw here’s some of the things I changed:

• Added an inverter to each gate for output
• Added diodes (tbh Im still not sure whether I should use diodes or resistors…….
• Created hierarchy sheets for AND, OR, and XOR gates (SUPER SUPER USEFUL

Completed the PCB design of XOR gate!! I tried to make it as compact as possible

GUESS WHATTT, IT’S TIME TO BUILD A FULL ADDER!!!!!!!!

Finally completed the schematic for an XOR gate. Despite building it on the breadboard, I still struggled with whether I should place a diode or a resistor…….But after doing some research I decided to go with a diode, and here’s the reasons:

• Resistor regulates the current indeed, but it’s based on R=V/I, so the voltage drop is not fixed
• Diode, on the other hand, ensures a 0.7V voltage threshold, preventing current from leaking

Completed the PCB design for the four gates!!! Btw i also ordered the PCB this time!!!

Completed schematic for AND, OR, NAND, and NOR gates!!!! Can’t believe I proceeded that fast lol, but Kicad still made it way easier than prototyping on breadboard trusttt

For the past hour I was learning how to build an XOR gate, it’s basically made of an NAND, AND, and OR

• Learning resource (Ben Eater my GOAT): https://www.youtube.com/watch?v=sTu3LwpF6XI&t=1s
• Took me a little while to figure out the circuit as I didn’t want to just copy and paste

OMG THIS IS SOOOOO FRUSTRATING…………but I finally completed my breadboard prototype for AND and OR gate, btw this is my first time using transistors so it took me quite a fair amount of time

Here are just some things to watch out for:

• Remember to put LED and resistors on the connector side, both to pull up and avoid current not flowing from the base to emitter!!!!
• Remember to put resistors for both transistors and the buttons, I just burnt two of them :(

OK I finally began my journey towards building a fully functional CPU!!!!!
First up ADDER:

• A design that can add two numbers
• How binary is used
• How logic gates are built are used, including AND, OR, NAND, NOR, and XOR

Updated my demo and published everything online including uploading my PCB design and schematic to Kicanvas!!!

Cleaned up and published everything online

Im so done with this but it was mostly finished!!! I will ship this right after some clean-up

For the past two hours I have been routing all the components, reducing ratlines from 200 all the way down to 20

• Connected all columns and rows
• Swapped some pins, such as moving all the column pins to the left
• Added GND vias (still more to add……

For the past hour I was reading TB6612FNG schematic and trying to apply it to my own. But here were the problems:

• I wanted to supply my RP2040 through both USB (5V) and battery (12V)
• What pins should I keep and crossed out cuz I wanted it to be minimal

Before ordering the PCB, here were what I did:

• Double-checked all the routes, including cleaning up some traces
• Change all traces to 0.18mm instead of 0.2mm
• Added LEDs to the following: VBUS (5V), 3V3, and GPIO2 (idk i just randomly chose it)

AHHHH SO FRUSTRATING!!! Apparently, it was not as easy as I thought, so many traffic jams

GUYS am I cooked……?

Here are the changes I decide to make:

• Move USB Port and the Chip to the top
• Replace THT diodes with SMD diodes (ik ik I said THT was better but im taking that back lmao

GUYS IM SO DONE WITH THIS……I was rewiring everything cuz of the stabilizer. I moved all the chips to the back and im SO DONE WITH THIS

Took me an hour to wire mostly everything up. Luckily I have the experience from RP2040 devboard and more space to spread out the components

BUT BUT BUT I just realized that I need some space for space key stabilizer!!!!!! AHHHHH BRO IM COOKED CUZ I GOTTA MOVE EVERYTHING AGAIN AND REWIRE THEM

Here were the things I did for the past two hours:

• Repositioned RP2040, crystal, and flash storage. Eventually, I flipped them to the front cuz it’s just cooler. Imagine if you can see all the internals you’re typing lol
• Move each row of diodes up to avoid unnecessary intersections
• Started routing, connected rows and columns and wired up USB port data traces
• Added copper zones and spread out the components

I finally placed every down in suitable positions (hopefully we’ll see when we get to routing
I also changed all the diodes from SMD to THT so that I don’t need to use via everywhere, and I could literally just trace either horizontally or vertically anyway I want

Question: Should I place USB port on top right corner or bottom right?

AHHHH THE MOST ANNOYING PART, here were the things I was trying to do:

• Place all the components in suitable positions
• Calculate the width of D+ and D- for USB
• Find tutorials to make sure everything is alright

Trust me patience is the secret sauce!!

For the past hour, I have been wiring my keyboard and I gotta be honest it was much easier than an RP2040 dev-board as there was much more space. Enjoy the process!!!

I completed the key layout and also decided to move all the diodes and parts to the back

Completed the schematic and the footprints!!!

Based off the experience from the two previous projects im finally now working on a full-size keyboard with integrated RP2040!! I just copied and pasted my my schematic from RP2040 and made some modifications specifically for keyboard, and I also mapped key switches