MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-44
14.8.1 SCI Registers
The SCI programming model includes the QSMCM global and pin control registers
and the DSCI registers.
The DSCI registers, listed in
, consist of five control registers, three status
registers, and 34 data registers. All registers may be read or written at any time by the
CPU. Rewriting the same value to any DSCI register does not disrupt operation; how-
ever, writing a different value into a DSCI register when the DSCI is running may dis-
rupt operation. To change register values, the receiver and transmitter should be
disabled with the transmitter allowed to finish first. The status flags in register SCxSR
can be cleared at any time.
*Reads access the RDRx; writes access the TDRx.
During SCIx initialization, two bits in the SCCxR1 should be written last: the transmitter
enable (TE) and receiver enable (RE) bits, which enable SCIx. Registers SCCxR0 and
SCCxR1 should both be initialized at the same time or before TE and RE are asserted.
A single half-word write to SCCxR1 can be used to initialize SCIx and enable the trans-
mitter and receiver.
Table 14-22 SCI Registers
Address
Name
Usage
0x30 5008
SCC1R0
SCI1 Control Register 0
See
for bit descriptions.
0x30 500A
SCC1R1
SCI1 Control Register 1
See
for bit descriptions.
0x30 500C
SC1SR
SCI1 Status Register
See
for bit descriptions.
0x30 500E
(non-queue mode only)
SC1DR
SCI1 Data Register
Transmit Data Register (TDR1)*
Receive Data Register (RDR1)*
See
for bit descriptions.
0x30 5020
SCC2R0
SCI2 Control Register 0
0x30 5022
SCC2R1
SCI2 Control Register 1
0x30 5024
SC2SR
SCI2 Status Register
0x30 5026
SC2DR
SCI2 Data Register
Transmit Data Register (TDR2)*
Receive Data Register (RDR2)*
0x30 5028
QSCI1CR
QSCI1 Control Register
Interrupts, wrap, queue size and enables
for receive and transmit, QTPNT.
See
for bit descriptions.
0x30 502A
QSCI1SR
QSCI1 Status Register
OverRun error flag, queue status flags,
QRPNT, and QPEND.
See
for bit descriptions.
0x30 502C — 0x30
504A
QSCI1 Transmit Queue
Memory Area
QSCI1 Transmit Queue Data locations (on
half-word boundary)
0x30 504C-6A
QSCI1 Receive Queue
Memory Area
QSCI1 Receive Queue Data locations (on
half-word boundary)
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Freescale Semiconductor, Inc.
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