The TFT I currently use for my PDAs is an Adafruit 3.5" tft touch screen breakout, which has a 50-pin FPC connector to talk to the actual LCD. But I can't find a screen like this ANYWHERE except by disassembling Adafruit's breakout. No idea where Adafruit gets em.
So I found that 50 pins are rare, 40 pins are more common. But my PCB is designed for a 50 pin, or was.
The new design has a 40 pin. I want to actually build this soon, but I need to be sure I can get the parts and have it actually work.
So... can I design a board that directly communicates with the LCD screen? Will I get the power circuitry right? I usually deal only with 5v or 3.3v logic, where most of the power and programming circuits are handled in a board designed by someone else.
Admittedly, I based the design largely off of referencing existing designs, like Sparkfun's ESP32 Thing or Adafruit's 3.2" TFT Breakout. So I can't take lots of credit for this, I mostly just hope I don't mess anything up. It *looks* good.
This new PDA should be much thinner, more reliable (my others always had wires breaking), and will have an ESP32 WROVER, which has extra SPI RAM built in. 5x Faster charging, and a much cleaner/smaller design.
Battery is working pretty well, but I still want faster charging
Can connect to WiFi and list WiFi networks, but it cannot be configured yet
TV-b-Gone works pretty well
Laser works great Yes my PDA has a Laser.
Primitive, yet clever, locking system.
Even hacks the screen to play music...
Can connect to a camera over WiFi
I won't illustrate all of that in this log, but it does all of those things. But after adding so much, the circuitry has become more complex...
... and error prone. The wires going to the resistive touch plates break regularly, so I have to fix them a lot. So I think I'm going to order a PCB. But when it works (99% of the time), it's quite nice. Here's the home screen:
Also - I have two now. You can also see the wireless program open in this image.
I actually started this project about six moths ago, but my first prototype was a brutal failure. I finally recreated my design last week and ordered parts, and I got everything working yesterday.
The old design was not nearly as good anyway, so I am sorta glad that it didn't work. :D
Here is my current design (no case yet), on my laptop:
I think it looks bigger than it is. I am really surprised about how small I made this thing.
Alright, now down to electronics; What's in this thing?
There are basically three parts: an ESP32, a battery, and a touchscreen. I can also add an SD card when I want to. As you can see, I *cleverly* held it together with tape. NOT recommended, because the Adafruit Feather board there pushes and dents the flex cable beneath it. This is my biggest reason for wanting to make a 3D printed case: I don't want to break the touchscreen.
There are two main issues with the current design: Communication with the display is really slow, and the touchscreen coordinates are off in a nonlinear way. In a new design I want to add a microcontroller just to control the LCD, using the 8-bit bus instead of SPI. This would also save pins on the Feather board, which has less pins than many ESP32 boards. I chose the Feather because the size is perfect, which for this project is very important.
Alright, enough technical stuff, I actually have a story. I took it to school all this week, but today was the first day it was fully working. I would pull it out and play with it for a moment from time to time, which makes people ask questions. This girl in my class asked about it, so I gave a brief explanation and gave it to her. It had Adafruit's paint program running. She played with it for almost half the two hour class, which surprised me because this is not a student who gets distracted often, and is highly intelligent. It made me thrilled that someone took such an interest in my work, so I took a picture of her holding it with her drawing:
I guess it says something when a person other than nerdy me takes an interest :)