SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 132

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
IRQ SELECTED
IRQ SELECTED
OPERATION
Mode Switching/Software Control
Software will execute P1284 negotiation and all operation prior to a data transfer phase under
programmed I/O control (mode 000 or 001). Hardware provides an automatic control line handshake,
moving data between the FIFO and the ECP port only in the data transfer phase (modes 011 or 010).
Setting the mode to 011 or 010 will cause the hardware to initiate data transfer.
If the port is in mode 000 or 001 it may switch to any other mode. If the port is not in mode 000 or
001 it can only be switched into mode 000 or 001. The direction can only be changed in mode 001.
Once in an extended forward mode the software should wait for the FIFO to be empty before switching
back to mode 000 or 001. In this case all control signals will be deasserted before the mode switch.
In an ecp reverse mode the software waits for all the data to be read from the FIFO before changing
back to mode 000 or 001. Since the automatic hardware ecp reverse handshake only cares about
the state of the FIFO it may have acquired extra data which will be discarded. It may in fact be in the
middle of a transfer when the mode is changed back to 000 or 001. In this case the port will deassert
nAutoFd independent of the state of the transfer. The design shall not cause glitches on the handshake
signals if the software meets the constraints above.
All others
All others
15
14
10
11
9
7
5
3
2
1
Table 9.7 Extended Control Register (b)
Table 9.8 Extended Control Register (c)
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
116
CONFIG REG B
CONFIG REG B
BITS 5:3
BITS 5:3
101
100
010
001
000
010
001
000
110
011
111
011
SMSC SCH311X
Datasheet