its_kronos

9/28/25 - FINAL DEVLOG
Yeah soooo i gave up trying to get the ESP part of the devboard working. I honestly have no idea where to debug next, so I decided that it's a lost cause

HOWEVER... there is still the SD card portion, which worked perfectly!

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Learning how to use the SD card and create an SPI interface was pretty interesting, but the compile time for the code was pretty painful (especially when I had to do it over and over again to test.
Anyways, a demo video will be coming soon!
time: 1.5h

Was able to debug everything except the connection between the STM and ESP
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Also managed to unjumble the bootloader ROM message

Was able to start the firmware

the UART route for communication with the ESP32 is

PC->STM->ESP->STM->PC

and I was able to verify that PC->STM, ESP->STM->PC works fine, but i dont know if STM->ESP works

I will have to debug later to find out why I can't make the connection

8/18/25
Got the PCB!!
Took a couple images in RAW format, which I spent quite a bit of time on
Each image was about 100mb, so I'll just share compressed ~10MB versions

GO TO GITHUB JOURNAL.MD TO SEE IMAGES

time: 30m

Since 0.8mm board with multicolor silkscreen adds 32 dollars, I remade the traces to work with 1.6mm (USB traces)

also changed the crystal to not have to be hand-soldered (cheaper to manufacture)

I started to add images to the back of the board, and one thing that was a challenge was how imported images always were bottom-most compared to patterns made natively in easyeda which was a pain to fix and move the shapes/reshape them.
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Eventually I was able to get it looking pretty good after quite a bit of time
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Also turns out that multicolor silkscreen requires a white board, and at 0.8mm board thickness it requires a special surcharge of 32 dollars, so I changed it to 1.6 and redid the USB traces, as board thickness impacts impedence.
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time: ~2h

CHECK JOURNAL.MD IN GITHUB FOR MORE PICTURES

This was a really big session especially due to today being the final day for the YSWS.

To start, I completely finished routing the board, which was really easy due to it pretty much being only straight lines.

After, I proceeded to check over everything in the schematic and the documentation, to make sure that everything would work

Unfortunately, the crystal that I was using for the RTC wouldn't work due to having too much of a load capacitance. This means that I must go with an extended component (which adds 3 dollars to the cost) and also reroute a small amount of the board.

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I also had to end up swapping RX and PB6 here, and the reason for that was that I thought RX (receive) would be sending the signals (I wasn't really thinking about it)
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Now, the only thing left is the art, and I was able to completely finish the top side, which in my opinion, looks really good, but took me a lot of time due to me being pretty bad at art.
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time: ~5h

I then spent quite a bit of time on routing, trying to make sure that it was neat, and when I got to the part where I had to route a second UART to communicate with the ESP32, I realized that Instead of using two GPIOs, I could use one and have a switch that switches between the REPL UART pins to the UART pins one would use for communicating with custom code.
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During this time, I was able to successfully route 50% of the GPIO headers (and there were a few moment where I pretty much boxed myself in really badly)

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This is quite tightly spaced (CHECK JOURNAL.MD IN REPO FOR IMAGE):

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time: 2h45m

Did a lot of the routing for the traces, and GPIO pins, especially the ones at the top of the STM32.
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However, after doing this I noticed that most of the ADC pins (convert Analog signals to binary) would be used for communication with the SD card and the wifi chip, which would be a waste, so I started to restart and better plan this layout, trying to make sure that I would keep in mind which signals aare more important than others (like communication between components > GPIO)
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time: 2h 30m

Did some research about a buck regulator, but turns out they would require way too many extended components, so although it would be less efficient, it would drive up the costs
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Changed up the layout a bit to make it neater as well as finished it, and added headers for debugging (SWDIO), and then started some of the start of routing, especially for important traces like USB and some of the power traces
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time: 2 hours

Started laying out everything and sourced other parts, such as the WIFI module and microSD reader, and then learned about how LDOs (the dropout voltage regulator I chose) would be ineficient, so now I'm trying to find a buck regulator instead
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time: 2 hours

Finished circuits for USB + ESD protection
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Did a lot of research on what type of converter I should use, since I would like for it to be compatable with different types of batteries, but this wasn't the easiest due to trying to make the board as cheap as possible. I was able to find a convertor that would allow for a stable conversion from 4.5 volts to 16 volts, which would be pretty good for things like 9V battery
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time: 1 hour

Ported over everything to easyEDA (without importing, just remade everything)
After, I added a 32.768 KHZ crystal for the RTC of the chip to be more accurate, especially since time tracking is something that can be fundamental for a board based on collecting data.
Finally, I started implementing USBC and esd protection with the USBLC6, but then I learned about how I could use TVS diodes for protection, which would be cheaper, and something I implement during the next session.
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Also, towards the end, I learned about how the specific MCU I'm using requires 1.5k Ohm pull up resistor on USB DP, and after doing some research I decided that the next session I would include an P channel mosfet to control it
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time: 2.5 hours

MORE PICTURES IN THE GITHUB JOURNAL.MD

Started by creating some ideas of what I generally wanted this project to be, and thanks to a few people, I came up with a basic idea.
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After coming up with the basic idea, I started to look at documentation for the STM32 chip I was going to be using, and started creating the schematic, which was pretty easy, but just a bit challenging since I've only been used to the Raspberry Pi documentation for their chips, which were very detailed and easy to follo whwne compared to STM
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Towards the end, I knew that a crystal that works with this chip would be hard to find. I looked at the only basic JLCPCB part (which would avoid a 3 dollar fee for assembly) that resonates at 16 MHZ, and it took about an hour of calculating to determine that it was probably fine. The only thing I wasn't able to calculate was how good the crystal would be over periods of time since I would need to measure how current flows through the crystal, which would be impossible without specific tools (oscilloscope) and the crystal itself.

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Also, I decided that I would be starting over and creating the PCB in easyEDA instead of Kicad since the Twist You Ship We Ship of Hackclub has two possible routes of funding for the PCB. One of them is to use any EDA but track your time, which doesn't include looking at documentation for 5 dollars an hour, or using easyEDA and receiving a grant from JLCPCB instead, with any amount of time

Using easyEDA would mean that I wouldn't have to worry about the PCB budget, especially since most of it isn't even tracked due to how documentation heavy hardware design can be

time: 3 hours

MORE PICTURES IN THE GITHUB JOURNAL.MD

Changed up looks for the website, so now it looks more like a finished product (I wish this took a lot less time than it did, but I'm pretty new to bootstrap and havent done web development for a long time
time: ~2h

• i've decided that my current wants for this project exceeds my current skill level, and i've been going about it the wrong way since the beginning (especially with the differences between how my code compiles and how a more professional language would compile its code)

• Instead, I am tweaking my goal to only include variable references, some built in functions, and printing

• Adding numbers wouldn't work with a + sign, but instead through an inbuilt function for ease of implementation

• Also the code will be a bit messy due to how i've coded the program, and I don't see another way to make it better other than to restart (which is something i really don't want to do, especially as my motivation falls from struggling so much)

• added functions for int() and str()!

• added addition and the ability to chain functions!

• added subtraction, just note that negatives must be defined as sub(0,n) instead of -n due to normal operators (5+5) being not implemented

• added division and multiplication, which supports string multiplication

• fixed \n so it'd actually work while printing

• error handling!

• Took a long while to determine the correct way to handle variables, but now finally have the framework and now I can support variable referencing and \ within strings!

• What I struggled with for this part was overthinking about how I would implement inbuilt functions, such as String(), which led to a lot of time spent wasted. Additionally, the order of the if statements was pretty important in regards to function

• I'm excited to later be able to add support to basic functions, and then be able to use different operations, such as a*50

The bug was indeed not fixed, and doing a string with operators next to eachother would raise an error

Decided to scrap all my current code after trying to fix it and start out with variables and a new token system

added variables!!

update styling a bit

researched and found out about a way to make the code truly run async

added print function and operations with strings, and +,-,*,/

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The most difficult part for sure was getting the order I should check for each operation to ensure that arithmetic errors don't happen
TIME: ~3h 30m

Added javascript code that runs after hitting the button with a good basis for expansion later on
found out that a for loop thats really long could cause the page to freeze, so I'll be trying to fix that next session.
TIME: 45m

Just started making everything look 100x better, which took a LOT of time looking at documentation to figure out how to get a certain look, especially with how long its been since I've done web development
Ended up adding a header navbar and started adding boxes to input code and for the output, however, I will be focusing on the functionality next rather than looks

Realized I don't even need to use flask (and could instead just use JS), but this will be restructured during the next session!
TIME: ~1h45m

Started by brainstorming ideas

Then, I started with doing quite a bit of research on how I would be able to bring my idea to a website, especially since downloading code and running it yourself is pretty annoying, so including a way to run custom code online would drastically improve QoL

I eventually settled on using Flask and React, and through the documentation, I was able to successfully install these two frameworks and get the website working

In order to use API with the backend, I created a page at the address /api/test, which when went to returned:

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Initally when trying to then push this code onto Github, I ran into an issue

After restructuring the repo to have a frontend and backend folder, the node_modules folder was no longer correctly referenced in .gitignore, causing there to be a problem with file sizes being too big

Since I didn't know much about react, I didn't originally know that node_modules was supposed to be in .gitignore, but after asking, I determined that it would be the best possible thing I could try (and it worked)

time: ~2h