I think what you are asking is about just learning basic electronics and the digital protocols that connect different "modules" (and what kind of extra circuitr

I think what you are asking is about just learning basic electronics and the digital protocols that connect different "modules" (and what kind of extra circuitry they need). For most consumer stuff (i.e. if you are not working on cars or industrial robots) you can get a lot done with just knowing about these three protocols: - UART: https://en.wikipedia.org/wiki/Uart https://en.wikipedia.org/wiki/Uart - SPI: https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bu... - I2C (sometimes called TWI - two wire interface): https://en.wikipedia.org/wiki/I%C2%B2C https://en.wikipedia.org/wiki/I%C2%B2C For more links for learning electronics check out my list of resources: https://github.com/monostable/awesome-electronics https://github.com/monostable/awesome-electronics.