Going back to electronic after a 20 years break

  This is the prototype board for the Cheap Spot Welder control board. It is a drop-in replacement for the original control board. It is based on a STM32F1 / bluepill board with a SSD1306 Oled screen, a rotary encoder, and a buzzer salvaged from an old 3D printer board. What does it bring ? Not much, it's cheap to make (<10$), it's opensource, it is easy to tune / change and it's massive overkill :) On the othe hand, a bluepill board is very cheap ~ 2$, so no point in trying to make something with a smaller MCU. It even runs freeRTOS. This is very much work in progress, all the building blocks are there, just need to do the magic sauce to glue all of them together.

  For the spot welder replacement board, i wanted to use a DC/DC converter to lower the 12v input voltage to something smaller (5V). The aim is to avoid heat and lower the current consumption, so that there will be no problem when the spot welding happens. The original boards consume about 10 mA, the STM32F1 based one consumes about 50 mA. I happened to have several of those mini 360 DC/DC converters. They are based on MP2307. The bluepill needs about 50 mA at 5v idling. The DC/DC is powered by 12V, outputs 5V  and needs ...70 mA! WTF ? I tested it with no load at all, still ~70 mA Changing the self and/or the output cap and/or the load makes the consumption varies a lot, between 7mA to 80 mA+load. Additionally the output oscillates , +- 0.5v at high frequency. From what i could see with a quick check, it needs a self/cap/... tuned to the input/output/load settings and if you dont have the right ones it will heat up and have a very bad efficiency. So unless you know you are in the good

  Still planning to pimping the cheap handheld console, so i bought a few of these cheap analog sticks. They are pretty simple, just 2 rotary potentiometers, converting the angle to a voltage divider. The voltage is VCC/2*(1+sin(Angle)) With angle from -90 degree to + 90 degree  A simple lookup table will easily invert that, to get the angle from the voltage.

It seems the screen is a fairly standard 16 bits parallel interface driven by ILI9341 style controller. The following annotated picture contains  a lot of guesswork, but this is how it seems to be connected : The main issue is finding how to switch it to 8 bits parallel instead of 16 bits.