micro-wire

This is an attempt at the smallest possible USB compliant device with V-USB. It uses an ATtiny10 to control a single WS2812 LED via USB.

The source started out as an amalganation of micronucleus and littlewire. All excess functionality was cut away.

Update 2014-01-07:

• It actually works on a ATtiny 10 now, yay! It still suffers from AVR-GCCs inability to generate proper 16 bit STS/LDS. Ticket to Atmel was submitted, let's see if they fix it.

Update 2014-03-19:

• I published a more detailed write-up of the project here.
• Custom PCB design is finished and ordered.

Features

• Enumeration.
• Only SETUP-request can be received.
• Responses are limited to strings from flash memory or zero sized replies.
• All SETUP packets that are not system request are forwarded to a WS2812 RGB LED on PB0.

Memory usage

• 1020 bytes Flash - Now down to 988 bytes with STS/LDS workaround.
  • Leaves 36 bytes of flash for addtional functionality!
• SRAM:
  • 28 bytes static variables
  • 2 bytes return stack
  • 2 bytes free
• Uses only regs R16-R31

License

This design is open source hardware shared under GPL V3.

Parts of this design are derived from http://www.littlewire.cc and V-USB.

Please honour the license by publishing the design files of derived designs and attributing the original work by linking back to the original repository.

Test set up