mc68hc908mr8 Freescale Semiconductor, Inc, mc68hc908mr8 Datasheet - Page 252

• Manufacturer Part Number: mc68hc908mr8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Communications Interface (SCI)
13.4.2 Transmitter
13.4.2.1 Character Length
13.4.2.2 Character Transmission
Technical Data
252
START
START
BIT
BIT
BIT 0
BIT 0
BIT 1
BIT 1
Figure 13-4
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 PTB1/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. Enable the SCI by writing a logic 1 to the enable SCI bit (ENSCI)
2. Enable the transmitter by writing a logic 1 to the transmitter enable
3. Clear the SCI transmitter empty bit by first reading SCI status
4. Repeat step 3 for each subsequent transmission.
BIT 2
BIT 2
in SCI control register 1 (SCC1).
bit (TE) in SCI control register 2 (SCC2).
register 1 (SCS1) and then writing to the SCDR.
Figure 13-3. SCI Data Formats
Serial Communications Interface (SCI)
BIT 3
BIT 3
shows the structure of the SCI transmitter.
BIT M IN SCC1 CLEAR
8-BIT DATA FORMAT
9-BIT DATA FORMAT
BIT M IN SCC1 SET
BIT 4
BIT 4
BIT 5
BIT 5
BIT 6
BIT 6
POSSIBLE
PARITY
BIT 7
BIT 7
BIT
POSSIBLE
PARITY
STOP
BIT 8
BIT
BIT
MC68HC908MR8 — Rev 4.1
START
NEXT
STOP
BIT
BIT
Freescale Semiconductor
START
NEXT
BIT