The MHVBoard is an Arduino clone kit, which does away with a second chip for USB comms, and instead uses V-USB to talk directly to the main microcontroller.
The kit has been designed to run soldering workshops, and is completely hand-solderable, even by complete newbies (all through hole components except for 1 large pin soltage regulator).
Programming is done via the USBAspLoader bootloader, which presents itself to the computer as a USB ASP programmer, which AVRDude knows how to talk to. Patches for the Arduino environment to teach it about this board are also included.
Since the chip directly has USB support, projects can easily emulate low-speed USB devices using the V-USB library. I have integrated USB Keyboard support into our MHVLib runtime library, and others have written similar libraries for the Arduino environment.
The MHVBoard also has a prototying area available, and our members have successfully used this for various interfaces (displays, nunchucks, etc). I have also built a software controllered 3V->5V boost regulator (using the MHVlib driver) in the proto-area so I can run off LiPos, but that is another project
Other unique features include a 20MHz clock (instead of 16MHz on other Arduino boards), as well as breadboard compatibility. A right angle connector can be mounted along the edge, allowing the whole board to be installed (standing vertically) into a breadboard, with all pins broken out.
MHVBoard – an Arduino Clone - [Link]
Here’s an article I wrote about reusing a cheap ($6) USBasp programmer for another project by flashing new code on to it. It’s a decent alternative to a more expensive USB dev board if you have a simple project that doesn’t require any pins or you can make do with the four SPI pins. The article discusses how to download new code using an external programmer or USBaspLoader. It also explains how to make it work with the Arduino IDE. At the end are a couple of evil demo programs showing how to use it as a USB HID keyboard.
Reflashing a betemcu USBasp Programmer - [Link]