Intro
The CRT BOY is a simple project that tries to build a Game Boy clone using a small CRT screen. The end result will look like a even more retro Game Boy from the 80ies. The micro controller based on the ESP32 is not so retro is strong enough to emulate consoles from the 90ties.
You should check out the prior relevant projects to have all the details on the esp32 game console componets:
https://bitluni.net/esp32-composite-video/
https://bitluni.net/esp32-composite-audio/
https://bitluni.net/esp32-color-pal/
CRT
The CRT I got from an old intercom is labeled as XG680F . I found similar ones in the google image search and checked the Chinese infos google translated.
https://world.taobao.com/item/39620771319.htm
A similar screen had more specs and info
https://world.taobao.com/item/12491150672.htm
Code
For testing of the first part I have used my Tetris clone https://github.com/bitluni/TetrisSpaceX. It seems to be a bit buggy but I’ll improve the code in the upcoming parts.
Circuit
(updated since part 2)
A one cell LiPo battery is used to power the system. A small usb charging circuit (TP4056) is used to charge the battery. This is the only component that is connected to the battery when the power switch is off. The out pins of the charger are not used since it is only capable of handling 1A of current. A DC-DC step-up converter converts the ~3.7V to ~12V needed by the CRT screen. Since the CRT needs ~600mA the current drawn from the battery at 3.7V will be around 2A. No external voltage regulator is needed anymore between the micro controller board and the battery. The maximum incoming voltage of 4.2V is ok for the microcontroller 5V rail. It is regulated down by the internal 3.3V regulator to power the processor. The 3.3V are also used to power the controller so it works on the same voltage level.
The operational amplifier works as a voltage follower and is powered by the 3.7V to have enough headroom for the maximum audio amplitude of 3.3V coming from the volume trimmer. The trimmer divides the voltage between the maximum amplitude and GND. To get more output current the two op-amps of the LM258 IC are used in parallel with the same input. To prevent the tow outputs to affect each other two 100Ohms resistors are used to output capacitor which converts the DC voltage to an AC voltage needed by the speaker.
Parts
These are the cheapest sources I found and used my self. I created affiliate links so you support my lab by using them. But it should work with other sources, too
ESP32 Mini KIT (~$7.58)
Prototype Boards (~$6.29 20pcs)
JST Connector Set (~$1.90)
Crimp Tool Amzon US UK DE
I don’t have a reliable source for the LM393 and the LM7805 but these are generic parts. You should be able to get from your common supplier.