Sometimes, you don't have direct access to the Raspberry Pi running your project. Perhaps it's installed outdoors with no display and keyboard attached. Or maybe it was squeezed into a compact chassis ...

You only really need two data wires to transfer a ton of data. Standards like UART, USB2, I2C, SPI, PS/2, CAN, RS232, SWD (an interface to program MCUs), RS485, DMX, and many others, all are a ...