Upgrade old boards to revision 3 (experimental)

This section describes how you can patch your old tinyUSBboard into a revision three board in only a few steps.
Roughly spoken there are four major milestones to do:

Soldering is required for the hardware part (step three). Of course the board needs to be switched off during the process.

Basically you first unsolder the cables end at PD7 for the PROGRAM button.
Then you disconnect the corresponding pin header from microcontrollers PIN (PD7). (This ensures an important safety measure: The future USB (D-) line must not be accessable on the outside (i.e. on a breadboard)).
Now also disconnect PIN PD6 from its inner USB D- connection rail. Connect the MCUs PIN PD6 with its corresponding pin header.

Extend the inner USB D- rail and connect it to MCUs PD7. (Its pin header stays disconnected!)
Solder the cable to MCUs PD6, which already should be connected to its pin header.

Done! Now you need to continue with step four...

Finally you may want to install a revision 3 update to get recent bootloader.