
PARALLEL PORT INTERFACE
S3FB42F
19-12
Register
Address
R/W
Description
Reset Value
PPINTCONH
0x67
R/W
Parallel port interrupt control high register
00h
PPINTPNDH
0x69
R/W
Parallel port interrupt pending high register
00h
[0]
Data received
The bit of PPINTPND is set when data is latched into the PPDATA
register's data field. This occurs during every High-to-Low transition of
nSTROBE when the parallel port data bus enable bit, PPCONL[7], is "0".
An interrupt is also generated if the ECP-with-RLE mode is enabled,
and if a data decompression is in progress.
[1]
Command received
The bit of PPINTPND is set when a command byte is latched into the
PPDATA register data field. If ECP-without-RLE mode is enabled,
the command received interrupt is issued whenever a run-length or
channel address is received. If ECP-with-RLE mode is enabled, the
command received interrupt is issued only when a channel address is
received. This event can be posted only when ECP mode is enabled.
The corresponding enable bit in the PPINTCON register determines
whether or not an interrupt request will be generated when a command
byte is received.
[2]
Invalid transition
The bit of PPINTPND is set when nSLCTIN transitions high-to-low in the
middle of an ECP forward data transfer handshaking sequence.
This interrupt is issued if nSLCTIN is low when nSTROBE is low or when
BUSY is high. This event can be detected only when ECP mode is
enabled and should return to compatibility mode.
[3]
Transmit Data Empty
The bit of PPINTPND is set to one when the transmit data register
(=PPDATA) can be written during an ECP reverse data transfers
PARALLEL PORT ACK WIDTH REGISTER
This register contains the 8-bit nACK pulse width field. This value defines the nACK pulse width whenever the parallel
port interface controller enters Compatibility mode, that is, when the parallel port control register mode bits,
PPCONL[5:4], are set to "01". The nACK pulse width is selectable from 0 to 255 XIN periods.
The nACK pulse width can be modified at any time and with any PPIC operation mode selection, but it can only be
used during a compatibility handshaking cycle. If you change the nACK width near the end of a data transfer (when
nACK is already low), the new pulse width value does not affect the current cycle. The new pulse width value would
be used at the start of the next cycle.
Register
Address
R/W
Description
Reset Value
PPACKD
0x6A
R/W
Parallel port acknowledge width data register
xxh
The value in the 8-bit field defines the nACK pulse width when Compatibility mode is enabled (PPCONL[5:4]=01).
The period of the nACK pulse can range from 0 to 255 XIN with 2 XIN steps.