Custom ESP32-S3 development board — professionally manufactured by JLCPCB. A far cry from where it all started. It Started in a School Science Lab — Around 1998 Most people who get into electronics start with a kit, a tutorial, maybe a breadboard and some LEDs. I started by sneaking ferric chloride out of a school science lab to etch my first PCB. That was around 1998. I was living in the Maldives — a small island nation in the Indian Ocean — where there was no electronics supply chain, no maker community, no local PCB fab. Just a chemistry cabinet at school, a copper-clad board from somewhere, and a lot of curiosity. This post is about what the next 25+ years of PCB prototyping looked like from there. The early wins with proper chemicals, the years of improvisation when those chemicals disappeared, the real injuries, the failed boards, and finally — the moment JLCPCB changed ever...
When you use microcontrollers and you are out of PIN's to connect some LED's for status or when you want to drive a binary clock with few pins left in microcontroller, there is a way that can solve this issue. Its called charlieplexing and if you know multiplexing you will have some idea of how it works. I will do an example using Arduino for demonstration. Charlieplexing is a method to drive multiple LED's with few pins available in your microcontroller. Here is the formula to calculate how many LEDs can be drive from N number of pins. Number of LED's = No. of PINS available ( No. of PINS available - 1) For example you have only 3 pins left in Arduino and you want to know how many LED's can be drive. Number of LED's = 3(3-1) Number of LED's = 3(2) Number of LED's = 6 So from 3 PINS you can drive 6 LED's. Since arduino have tri-state output (INPUT, HIGH and LOW) its easy to drive the LED's using this method. how leds are connect...