mc68hc08qa24 Freescale Semiconductor, Inc, mc68hc08qa24 Datasheet - Page 214

• Manufacturer Part Number: mc68hc08qa24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Communications Interface (SCI)
17.4.1 Data Format
17.4.2 Transmitter
17.4.3 Character Length
17.4.4 Character Transmission
Technical Data
212
The SCI uses the standard non-return-to-zero (NRZ) mark/space data
format illustrated in
Figure 17-4
The transmitter can accommodate either 8-bit or 9-bit data. The state of
the M bit in SCI control register 1 (SCC1) determines character length.
When transmitting 9-bit data, bit T8 in SCI control register 3 (SCC3) is
the ninth bit (bit 8).
During an SCI transmission, the transmit shift register shifts a character
out to the PTE0/TxD pin. The SCI data register (SCDR) is the write-only
buffer between the internal data bus and the transmit shift register.
To initiate an SCI transmission:
1. Initialize the Tx and Rx rates in the SCI baud register (SCBR)
2. Enable the SCI by writing a logic 1 to ENSCI in SCI control register
START
START
BIT
BIT
($0019). See
1 (SCC1) ($0013).
Serial Communications Interface (SCI)
BIT 0
BIT 0
shows the structure of the SCI transmitter.
BIT 1
BIT 1
BIT 2
BIT 2
Figure 17-3. SCI Data Formats
Figure
17.9.7 SCI Baud Rate
BIT 3
BIT 3
(BIT M IN SCC1 CLEAR)
8-BIT DATA FORMAT
9-BIT DATA FORMAT
(BIT M IN SCC1 SET)
17-3.
BIT 4
BIT 4
BIT 5
BIT 5
BIT 6
BIT 6
Register.
POSSIBLE
PARITY
BIT 7
BIT 7
BIT
POSSIBLE
Freescale Semiconductor
PARITY
STOP
BIT 8
BIT
BIT
START
NEXT
STOP
BIT
BIT
MC68HC08QA24
START
NEXT
BIT