Time was when chip makers’ processor evaluation boards were well beyond the reach of ordinary mortals. That didn’t matter, of course: ordinary mortals weren’t interested in small, nude motherboards designed to help designers of embedded systems judge a microprocessor’s suitability for the application they were working on.
When it comes to hacking hardware there’s an easy way and there’s a hard way.
The hard way involves connecting peripherals direct to one of the standard buses supported by your Raspberry Pi, Arduino, Beaglebone or whatever. Buses like I²C, SPI, UART and 1-Wire. You’ll need to take care with your wiring: have you got the right pull-up or pull-down resistor? Is there too much capacitance in the line?