RapideUSB

How to use this? USB without Arduino
Alternate version for SNES joypad adapter: SNES pad USB adapter
Alternate version for ATtiny2313 and better with some fixed RapideUSBII

Summary

• You go with the Zener diodes approach: your mCU runs on 5v, life is easy. For the small downsides see V-USB hardware documentation.
• You plan to use pins D2 and D4 for your connectivity. You can use other pins though, you'll have to not solder the jumpers and wire D+/D- to the pins you want
• You plan to use ATtiny 2313 DIP or ATmegaxx8 SMD family

Self-criticizing and possible improvements

• [High] Add holes for D+/D- to plug a USB cable directly instead of a micro/mini plug
• [High] OTG connection as a client? Maybe with a solder jump or allow to solder these special connectors? (ie: to be able to connect a smartphone)
• [Medium] Make those lines that carry power (VCC & GND) bigger, it's just signal size now, no way it can draw more than a few tens of mA)
• [Medium] Put a solder mask on the bottom for the power rail! Hard to figure where is gnd/vcc...
• [low] Add a V-USB logo
• [low] The power rail have solder mask on top (bottom is ok)... how did I do this miracle? Replace with regular ones
• [low] Provision for external power + USB connection, like a self powered hub or allow the connected smartphone to connect and charge

Schematics

README ! Things to know

• The board has 2 solder jumpers labelled D+=D2 and D-=D4: if you use D2 (as D+) and D4 (as D-) as default, just solder close these jumpers. If not, let them open and join the solder pad to the pin you're using.
  • Corollary: if you don't solder these pads but use my default pins, nothing will work.
• PORT D is common to both mCU, PORT C is only available for ATmega328 and PORT B is implemented separately. Reason is that the ISP wiring on both mCU go to PORT B but the pins are different: MISO is PB6 on the tiny and PB4 on the mega. It would result in a big mess shorting pins. I could have put solder jumpers but I had space so...
• For all the ports the pin 0 is the square 口 pad. Count up from there, farthest is number 7.
• Board is a default 5cm x 5cm
  • You can cut the board at the level of the 3rd free row (where there's the "cut ok" top silk message). You board will become a 5cm x 3.3cm in case you need space.

Setting the fuses

# Set the fuses
avrdude -pt2313 -cavrispmkII -u  -Ulfuse:w:0xce:m -Uhfuse:w:0xdf:m -Uefuse:w:0xff:m

BOM

Code

Pictures