Day 1: Brainstroming (May 25)
I knew that I had wanted to create a custom devboard that would both beat every devboard on planet earth in value and features. My first step was choosing a micro-controller. As I had already designed devboard around the weaker rp2040, I decided to step things up with an RP2350B.
This would have some 48 GPIO, which should be ample for any maker. As mentioned previously, I wanted every featuer that I could afford to put into the board, and with a budget of $150 USD, I felt I definetly could get a lot done. After much contemplation, I decided that I wanted to add the following featuers:
1. WIFI
2. A built-in OLED
3. GPS
4. an IMU
5. Built in battery holder
6. BUilt in battery charger
7. A 5V output line
8. A 3.3V line
9. USB-C and USB-micro input ports
10. USB-A / USB-C output ports (for phone-charging, etc.)
11. D2 - A MicroSD card reader
12. D3 - An H-Bridge
And hopefully more to come, though I don't really know
Anyways, after getting my goal sort of set. I decided to get ChatGPT to help with some more brainstorming, as I was pretty uncertain about the programmablity, as I would love to have a high-performance board that anyone could use easily. This was probably my biggest mistake The way ChatGPT explained the WIFI stuff was with basically no detail, and no matter how much I prompted it, it gave me nothing useful. What a waist of an hour.
I decided upon using a 4 layer PCB, using easyEDA to make it as quite frankly Kicad is one of the most annoying peices of software I have used (That's probably because I'm used to using easyEDA) The layers would be like this 1. Signals 2. Ground 3. Power 4. Signals
So then, after bothering with all of this I finally set out to start the desing of the board. I looked through those datasheets, and immidiately found my first problem, the power supply. It uses some weird switching super-sensitve powersupply, and as of now I am still working upon a solution.
2 hrs later
Finally found a half solution, though I don't know if it will really work. It is an absolutely essential part of the board. IDK what to do.
HOURS COMPLETED: 6 (TOTAL:6)
Day 2: Starting Power and WIFI (May 26)
Ok so there is this weird inductor that the rp2350 uses, so I took a deep dive into the schematic pages and the guidlines, and I think that my current design will, in fact, work.
On the other hand, getting wifi and stuff to work seems like it is going to be the biggest challenge. Getting wifi is honestly the most stupedest and hardest thing I have worked on so far. What, after like an hour of datasheet diving, I found out that to get the official stuff to work it is going to be way to hard, so I am going to add another board onto the thing, an esp32 board, making this have 2 CPUs: you can chose either one to work with, or both. This is going to make power delivery and stuff more complicated, and it is going to require more USB ports to be able to program this effectively, not to mention that as WIFI is so hard to get working it is going to require some very complicated wiring. With those weird things, I think I will have to use a 4-layer pcb, especially as USB can be very finiky with a ground that is far away.
Also, I added a Micro-SD card reaader as a feature I wanted. After seeing how complex wifi is, and how long it took to get working, not to mention the fact that I now have two processors to take care of and make everything work, I am thinking of expanding my budget to the $350 that the advanced projects have availible. Just as the advanced projects page said, I saw that my previous experience was really helpful.
Ok I have gotten everything started, and progress is slow but steady. I have finished the 3.3V to 1.1V switching converter, a big headache in and of itself. Then, I finished the buttons.
The switching converter is what I was talking about the problem yesterday, and not only is it painful with the schematic, but as there are so many things so densly packed, it is hard to get all the wires doing things even with all of these layers.
HOURS COMPLETED:4.5 (TOTAL:10.5)
Day 3: A bit of studying (May 27)
Just a did some studying of the schematics of the rp2350. I also thought of adding an H-bridge, so that you don't have to worry about external wiring. I also did some pcb desing, mainly with the flash.
HOURS COMPLETED: 1 (TOTAL:11.5)
Day 4: WHY WIFI????????????????????????? (May 28)
I'm a be honest: wifi might not work. One after and other after another, the problems keep coming. The ESP32 that I was going to use has no real way of connecting it to a USB port, but the other one that I could use requires JLCPCB Standard Assembly. I honestly don't know what to do, as Standard cost $25 vs Economic at $8 for the setup costs. See below for the image of the ESP32 that I was going to use.
I want to use:
But I don't want to spend an extra $18 to use it 😿
On the other front, it seems like the rp2350B part of the board should come along pretty well, as my desing looks close enough to the recomended design.
HOURS COMPLETED:1.5 (TOTAL:13)