LPC47M112_07 SMSC [SMSC Corporation], LPC47M112_07 Datasheet - Page 87

• Manufacturer Part Number: LPC47M112_07
• Description: Enhanced Super I/O Controller with LPC Interface
• Manufacturer: SMSC [SMSC Corporation]

Enhanced Super I/O Controller with LPC Interface
Datasheet
EPP 1.9 Read
The timing for a read operation (data) is shown in timing diagram EPP Read Data cycle. The chip inserts wait states into
the LPC I/O read cycle until it has been determined that the read cycle can complete. The read cycle can complete
under the following circumstances:
1
2.
Read Sequence of Operation
1.
2.
3.
4.
5.
6.
7.
8.
9.
EPP 1.7 OPERATION
When the EPP 1.7 mode is selected in the configuration register, the standard and bi-directional modes are also
available. If no EPP Read, Write or Address cycle is currently executing, then the PDx bus is in the standard or bi-
directional mode, and all output signals (STROBE, AUTOFD, INIT) are as set by the SPP Control Port and direction is
controlled by PCD of the Control port.
In EPP mode, the system timing is closely coupled to the EPP timing. For this reason, a watchdog timer is required to
prevent system lockup. The timer indicates if more than 10usec have elapsed from the start of the EPP cycle to the end
of the cycle. If a time-out occurs, the current EPP cycle is aborted and the time-out condition is indicated in Status bit 0.
Software Constraints
Before an EPP cycle is executed, the software must ensure that the control register bits D0, D1 and D3 are set to zero.
Also, bit D5 (PCD) is a logic "0" for an EPP write or a logic "1" for and EPP read.
EPP 1.7 Write
The timing for a write operation (address or data) is shown in timing diagram EPP 1.7 Write Data or Address cycle. The
chip inserts wait states into the I/O write cycle when nWAIT is active low during the EPP cycle. This can be used to
extend the cycle time. The write cycle can complete when nWAIT is inactive high.
Write Sequence of Operation
1.
2.
3.
4.
5.
6.
7.
EPP 1.7 Read
The timing for a read operation (data) is shown in timing diagram EPP 1.7 Read Data cycle. The chip inserts wait states
into the I/O read cycle when nWAIT is active low during the EPP cycle. This can be used to extend the cycle time. The
read cycle can complete when nWAIT is inactive high.
SMSC DS – LPC47M112
If the EPP bus is not ready (nWAIT is active low) when nDATASTB goes active then the read can complete when
nWAIT goes inactive high.
If the EPP bus is ready (nWAIT is inactive high) then the chip must wait for it to go active low before changing the
state of WRITE or before nDATASTB goes active. The read can complete once nWAIT is determined inactive.
The host initiates an I/O read cycle to the selected EPP register.
The chip tri-states the PData bus and deasserts nWRITE.
Chip asserts nDATASTB or nADDRSTRB indicating that PData bus is tri-stated, PDIR is set and the nWRITE signal
is valid.
Peripheral drives PData bus valid.
Peripheral deasserts nWAIT, indicating that PData is valid and the chip may begin the termination phase of the
cycle.
a)
nADDRSTRB. This marks the beginning of the termination phase.
b)
LAD[3:0] signals, followed by the TAR to complete the read cycle.
Peripheral tri-states the PData bus and asserts nWAIT, indicating to the host that the PData bus is tri-stated.
Chip may modify nWRITE, PDIR and nPDATA in preparation for the next cycle.
The host sets PDIR bit in the control register to a logic "0". This asserts nWRITE.
The host initiates an I/O write cycle to the selected EPP register.
The chip places address or data on PData bus.
Chip asserts nDATASTB or nADDRSTRB indicating that PData bus contains valid information, and the WRITE
signal is valid.
If nWAIT is asserted, the chip inserts wait states into I/O write cycle until the peripheral deasserts nWAIT or a time-
out occurs.
The chip drives the final sync, deasserts nDATASTB or nADDRSTRB and latches the data from the internal data
bus for the PData bus.
Chip may modify nWRITE, PDIR and nPDATA in preparation of the next cycle.
If WAIT is not asserted, the chip must wait until WAIT is asserted.
The chip latches the data from the PData bus for the internal data bus and deasserts nDATASTB or
The chip drives the sync that indicates that no more wait states are required and drives the valid data onto the
DATASHEET
Page 87
Rev. 02-16-07