Add USB Host Support To Your MCU Design

The Maxim MAX3421E allows you to add a USB Host port to any microprocessor with an SPI interface.  This IC has recently returned to active production after being listed as not recommended for new designs.  It is offered as an Arduino shield (daughter board) from Circuits@Home and the code library for the USB Host Shield is on github.  You can find many articles on the design and use of the USB shield on the Circuits@Home blog.  The design is open hardware and you can order it from Batch-PCB as well.

For commercial projects, the MAX3421E is supported by USB Stacks from HCC-Embedded and Micro Digital.  HCC-Embedded also has an SD card module to add a USB Host to any board with an SPI capable SD card socket.  The schematics and layout are a free download from the website.

The MAX3421EVKIT-1 from Maxim can also be used for developing a USB stack for individual devices.  It can be ordered directly from Maxim ($57) or from Digikey ($62).  You can start with the MAX3421E EVKIT-1 Software and User Guide to develop your own driver for targeted devices.  I have been working with the MAX3421E with an ARM processor board and have added support for a mouse, keyboard, and hub to the design.