MMC2107 - Freescale Semiconductor

Freescale Semiconductor, Inc.
Serial Communications Interface Modules (SCI1 and SCI2)
Functional Description
16.8 Functional Description
The SCI allows full-duplex, asynchronous, non-return-to-zero (NRZ)
serial communication between the MCU and remote devices, including
other MCUs. The SCI transmitter and receiver operate independently,
although they use the same baud rate generator. The CPU monitors the
status of the SCI, writes the data to be transmitted, and processes
received data.
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Freescale Semiconductor, I
16.9 Data Format
The SCI uses the standard NRZ mark/space data format shown in
Figure 16-13.
Each frame has a start bit, eight or nine data bits, and one or two stop
bits. Clearing the M bit in SCCR1 configures the SCI for 10-bit frames.
Setting the M bit configures the SCI for 11-bit frames.
When the SCI is configured for 9-bit data, the ninth data bit is the T8 bit
in SCI data register high (SCIDRH). It remains unchanged after
transmission and can be used repeatedly without rewriting it. A frame
with nine data bits has a total of 11 bits.
START
BIT
START
BIT
10-BIT FRAME
M = 1 in SCICR1
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
11-BIT FRAME
M = 1 IN SCICR1
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Figure 16-13. SCI Data Formats
STOP
BIT
BIT 8
NEXT
START
BIT
STOP
BIT
NEXT
START
BIT
MMC2107 – Rev. 2.0
Technical Data
MOTOROLA Serial Communications Interface Modules (SCI1 and SCI2) 349
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