MFC2000 Datasheet, PDF (339/426 Pages) List of Unclassifed Manufacturers – Multifunctional Peripheral Controller 2000

Hardware Description
MFC 2000 Multifunctional Peripheral Controller 2000
17.5.2 Nibble Mode Timing
The Nibble mode is the most common way to get reverse channel from printer or peripheral. This mode is usually
combined with the compatibility mode or a proprietary forward channel mode to create a complete bi-direction
channel.
The Nibble Mode Phase transitions:
1. Host signal ability to take data by asserting AUTOFDn low
2. Peripheral responses by placing first nibble on status lines(FAULTn,SLCTOUT,PE and BUSY)
3. Peripheral signals valid nibble by asserting ACKn low
4. Host sets AUTOFDn high to indicate that it has received the nibble and is not ready for another nibble.
5. Peripheral set ACKn high for the second nibble.
AUTOFDn
ACKn
FAULTn
SLCTOUT
PE
BUSY
BITS[1:4]
BITS[5:8]
Figure 17-3. Nibble Mode Data Transfer Cycle
100723A
Conexant
17-17