Add USB to Anything

Abstract: The MAX3420E makes it easy to design a USB peripheral using a general-purpose microcontroller. After introducing the MAX3420E, this article focuses on the device's SPI interface. The article demonstrates how to access the device either by using a hardwired SPI unit or by bit-banging general-purpose I/O pins. Example C code is given for a USB design that uses the MAXQ2000 microcontroller.