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Parallel Interface Port (PIP)
MC68360 USER’S MANUAL
7.13.7.2 PIP CONFIGURATION REGISTER (PIPC). The PIPC is a 16-bit read-write regis-
ter that is cleared at reset. The PIPC determines all PIP options.
STR —Start (Valid for a Transmitter Only)
This bit is valid only when the T/R bit is set to 1 (transmitter). Setting this bit to 1 causes
the RISC controller to poll the Tx BD. Thus, the user should prepare a Tx BD and set its
R- bit before setting STR. STR is cleared after one system clock.
Bits 14–12—Reserved
SACK—Set Acknowledge
When set, this bit will assert the receiver’s ACK output (low voltage), regardless of the re-
ceiver’s state. SACK should be used when implementing the IEEE P1284 Bidirectional
Centronics protocol.
CBSY—Clear BUSY
This bit is used by host software to force the BUSY signal low for a Centronics receiver.
When CBSY is set, the BUSY signal will output at 0 (low voltage). CBSY is cleared after
the PIP negates the BUSY signal.
NOTE
The T/R bit should be set to 0 (receiver) if CBSY is used.
SBSY—Set BUSY
This bit is used by host software to force the BUSY signal high for a Centronics receiver.
When SBSY is set, the BUSY signal will output a 1 (high voltage). SBSY is cleared after
the PIP asserts the BUSY signal.
NOTE
The T/R bit should be set to 0 (receiver) if SBSY is used. Also,
EBSY would normally be set by the user before SBSY is set. (If
EBSY is cleared, the PIP ignores the STB signal until CBSY is
set in software.)
EBSY—Enable BUSY (Receiver)
This bit has a different definition depending on whether T/R is set to receiver or transmit-
ter.
When T/R = 0 (PIP is a receiver), the definition is as follows:
0 = Disable BUSY signal generation on PB0 for the receiver.
1 = Enable the BUSY output signal on PB0. EBSY will only take effect if bit 0 of PBPAR
is 0 to configure this pin to belong to the PIP and bit 0 of PBDIR is 1 to make this
pin an output.
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14
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STR
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SACK
CBSY
SBSY
EBSY
TMOD
MODL
MODH
HSC
T/R
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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