FIRST BIG SUCCESS...
After some try and error I completed Level1
: CLOCK is ALWAYS sent from WRITER.
- a command is sent with preamble 0xA5A5A5A followed by 8 bit COMMAND
- after last bit from command was sent DATA switches directions
- IC sends back 0xAA and 4 bit status (maybe something like this: b0001 = ok, b0000 = error), clock must be supplied by WRITER
This only works with VPP > 5.5 V.
JS
EDIT: 3.3V was used for VDD.