Parallel Interface Port (PIP)
MPC885 PowerQUICC Family Reference Manual, Rev. 2
33-22
Freescale Semiconductor
interrupt is generated when the BD finishes processing. Note that a single received data frame can span
several buffers.
For each transfer, the PIP controller generates ACK and BUSY handshake signals on the Centronics
interface. The ACK pulse width and the timing of BUSY with respect to ACK are determined by the timing
parameter register PTPR.
Figure 33-22
shows the PIP configured as a Centronics receiver. The SELECT, PERROR, and FAULT
signals shown are not automatically generated; they are controlled by software and driven on
general-purpose outputs.
Figure 33-22. PIP as a Centronics Receiver
33.9.2.1
Centronics Rx Errors and the PIPE
The Centronics receiving error is described in
Table 33-14
.
The relevant PIPE event bits for Centronics receiving are CCR, BSY, RCH, and RXB; see
Section 33.4.2,
“PIP Event Register (PIPE).”
For core-controlled receiving, only the character-based RCH interrupt
applies.
Table 33-14. Centronics Rx Error
Error
Description
BD Busy
The current BD to be processed is not empty. PIPE[BSY] is flagged. The channel resumes receiving after
user software prepares the BD.
PB31
PB30
SELECT
BUSY
ACK
STB
PB28
FAULT
PB29
PERROR
Host
MPC885
(Centronics Device)
Data[0:7]
PB[16:23]
PB14
PB15
[*]
[*]
[*]
[*]
[*] – Optional
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