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16.7.5.6.2 SIRP Indication When RDM = 01. For the receiver, RxPTR is used, depending
on the portion of the serial interface RX RAM that is currently active. For the transmitter,
TxPTR is used, depending on the portion of the serial interface TX RAM that is currently
active. If the corresponding VTx or VRx bit is set, then:
• RAPTR contains the address of the currently active RX RAM entry. The serial interface
RAM receive address block that is used is 0–63 and the CRORA bit is set to 0 in the
SISTR.
• RBPTR contains the address of the currently active RX RAM entry. The serial interface
RAM receive address block that is used is 64–127 and the CRORA bit is set to 1 in the
SISTR.
• TAPTR contains the address of the currently active TX RAM entry. The serial interface
RAM transmit address block that is used is 128–191 and the CROTA bit is set to 0 in
the SISTR.
• TBPTR contains the address of the currently active TX RAM entry. The serial interface
RAM transmit address block that is used is 192–255 and the CROTA bit is set to 1 in
the SISTR.
16.7.5.6.3 SIRP When RDM = 10. This is the simplest case, since each pointer is used
continuously and only has one function.
• RAPTR contains the address of the currently active RXA entry.
• RBPTR contains the address of the currently active RXB entry.
• TAPTR contains the address of the currently active TXA entry.
• TBPTR contains the address of the currently active TXB entry.
16.7.5.6.4 SIRP When RDM = 11. In this case, each pointer is used continuously, but
points to different sections of the SI RAM, depending on whether the pointer's value is in the
first half (0–15) or the second half (16–31).
• RAPTR contains the address of the currently active RXB entry. If the pointer has a value
from 0–15, the current-route RAM is SI RAM address block 0–31 and the CRORB bit is
set to 0 in the SISTR. If the pointer has a value from 16–31, the current-route RAM is
SI RAM address block 32–63 and CRORB is set to 1 in the SISTR.
• RBPTR contains the address of the currently active RXB entry. If the pointer has a value
from 0–15, the current-route RAM is SI RAM address block 64–95 and the CRORB bit
is set to 0 in the SISTR. If the pointer has a value from 16–31, the current-route RAM
is SI RAM address block 96–127 and CRORB is set to 1 in the SISTR.
• TAPTR contains the address of the currently active TXA entry. If the pointer has a value
from 0–15, the current-route RAM is SI RAM address block 128–159 and the CROTA
bit is set to 0 in the SISTR. If the pointer has a value from 16–31, the current-route RAM
is SI RAM address block 160–191 and CROTA is set to 1 in the SISTR.
MOTOROLA
MPC823e REFERENCE MANUAL
Communication Processor Module
16-143
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