Here on this unit I've yet to clean off the flux, but is working very well, soldering is very difficult without a metal positioning mask, but is on my to-do list. VCC, the RX an TX serial lines, programming pin (UPDI), I2C bus communication pins (SDA + SCL), and the ground pin are all shown. What makes this "yet another rgb pcb" better than the rest is its fast refresh rate, not using a single data line for all leds, but seven! So each signal line has just five rgb leds on it. In the future I plan on using two of these display boards with an ESP32 C6 system, I will call it the "Radio Badge" project. In the two videos below I have a vertical/horizontal program running, and ALSO an A/D running a level meter with random input, but using the A/D function, so you can see the refresh capabilities.