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For each transfer, the PIP drives the data on the Centronics interface data lines and
generates a strobe pulse, assuming the previous data has been acknowledged and the
minimum setup time requirement is met. Strobe pulse width and setup time parameters are
set in the PIP timing parameters register (PTPR). Note that one data frame can span several
buffers with a maskable interrupt generated after each BD is processed.
Figure 33-21 shows the PIP conÞgured as a Centronics transmitter.
Figure 33-21. PIP as a Centronics Transmitter
33.9.1.1 Centronics Tx Errors and the PIPE
The Centronics transmission errors are described in Table 33-13.
Error
BD Not
The current BD to be processed is not ready. PIPE[TXE] is ßagged. The channel continues sending after
Ready
S/W prepares the BD and sets PIPC[STR].
Printer
The printer is off-line. TxBD[S] and PIPE[TXE] are ßagged. The channel resumes sending after
Off-Line
. Note that SMASK[S] must be set to sense this printer status line when the CP is controlling
TRANSMIT
the transfer.
Printer
The printer has a fault condition. TxBD[F] and PIPE[TXE] are ßagged. The channel resumes sending
Fault
after
RESTART TRANSMIT
controlling the transfer.
Paper Error The printer has an error in its paper path. TxBD[PE] and PIPE[TXE] are ßagged. The channel resumes
sending after
when the CP is controlling the transfer.
The relevant PIPE ßags during Centronics transmission are TXE, TCH, and TXB; see
Section 33.4.2, ÒPIP Event Register (PIPE).Ó For core-controlled transmissions, only the
character-based TCH interrupt applies.
MOTOROLA
MPC860
(Host)
PB[16:23]
PB15
PB14
PB31
PB30
PB29
PB28
[
*
Table 33-13. Centronics Tx Errors
. Note that SMASK[F] must be set to sense this printer status line when the CP is
. Note that SMASK[PE] must be set to sense this printer status line
RESTART TRANSMIT
Chapter 33. Parallel Interface Port
Part V. The Communications Processor Module
Centronics
Data[0:7]
STB
ACK
[
]
*
BUSY
[
]
*
SELECT
[
]
*
PERROR
[
]
*
FAULT
] Ð Optional
Description
Device
RESTART
33-21
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