Queued Serial Multi-Channel Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
15-51
15.7.6
SCI Pins
The RXD1 and RXD2 pins are the receive data pins for the SCI1 and SCI2, respectively. TXD1 and TXD2
are the transmit data pins for the two SCI modules. The pins and their functions are listed in
15.7.7
SCI Operation
The SCI can operate in polled or interrupt-driven mode. Status flags in SCxSR reflect SCI conditions
regardless of the operating mode chosen. The TIE, TCIE, RIE, and ILIE bits in SCCxR1 enable interrupts
for the conditions indicated by the TDRE, TC, RDRF, and IDLE bits in SCxSR, respectively.
15.7.7.1
Definition of Terms
Bit-time
The time required to transmit or receive one bit of data, which is equal to one cycle
of the baud frequency.
Start bit
One bit-time of logic zero that indicates the beginning of a data frame. A start bit
must begin with a one-to-zero transition and be preceded by at least three receive
time samples of logic one.
Stop bit
One bit-time of logic one that indicates the end of a data frame.
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
Field
—
R8/T8 R7/T7 R6/T6 R5/T5 R4/T4 R3/T3 R2/T2 R1/T1 R0/T0
SRESET
0000_000
Undefined
Addr
0x30 500E
Figure 15-29. SCI Data Register (SCxDR)
Table 15-27. SCxDR Bit Descriptions
Bits
Name
Description
0:6
—
Reserved
7:15
R[8:0]/
T[8:0]
R[7:0]/T[7:0] contain either the eight data bits received when SCxDR is read, or the eight data
bits to be transmitted when SCxDR is written. R8/T8 are used when the SCI is configured for
nine-bit operation (M = 1). When the SCI is configured for 8-bit operation, R8/T8 have no
meaning or effect.
Accesses to the lower byte of SCxDR triggers the mechanism for clearing the status bits or for
initiating transmissions whether byte, half-word, or word accesses are used.
Table 15-28. SCI Pin Functions
Pin Names
Mnemonic
Mode
Function
Receive Data
RXD1, RXD2
Receiver disabled
Receiver enabled
General purpose input
Serial data input to SCI
Transmit Data
TXD1, TXD2
Transmitter disabled
Transmitter enabled
General purpose output
Serial data output from SCI
Summary of Contents for MPC561
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Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
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