It's a New Year - How about a USB Topic

Welcome to 2013! I hope you had a great 2012 and enjoyed your holidays.  I took some time off and I am now feeling refreshed and energized to start 2013.  I was made aware by a friend today of a bit-banged USB implementation on an MSP430.  This is very exciting because the only options of doing this in low cost designs is to add an additional translation chip, usually a USB to uart bridge. For those of you interested in going right to the content, check out this link.

I did want to give a little background on why someone would want a bit-banged USB implementation on a microcontroller.  Today USB is the most ubiquitous interface available in the market.  The connector was largely driven by the consumer space but has started to adapt quite well to markets I am more familiar with, medical and industrial.  Although USB is widely used, it is not the easiest thing to understand.  There are numerous profiles that have to be coded in software and different configurations that have to be accounted for in hardware.

Traditionally if a user wants to a add a USB connection they either have to get a processor with a USB controller or they have to insert a USB to UART bridge chip in between their microcontroller and the USB port.  There are numerous suppliers with USB to UART bridge chips and the most popular is probably FTDI.

There are numerous open source projects that I am aware of that are starting to implement the bit-banged USB implementation without a bridge chip in between.  A very popular implementation is the one for the AVR micros called V-USB - link.

Here is the schematic required to add a USB connection for the V-USB implementation, pretty simple: