Datasheet

Chapter 13 Serial Communications Interface (S12SCIV2) Block Description
Freescale Semiconductor MC9S12C-Family / MC9S12GC-Family 395
Rev 01.24
13.4.1 Data Format
The SCI uses the standard NRZ mark/space data format illustrated in Figure 13-10 below.
Figure 13-10. SCI Data Formats
Each data character is contained in a frame that includes a start bit, eight or nine data bits, and a stop bit.
Clearing the M bit in SCI control register 1 configures the SCI for 8-bit data characters.A frame with eight
data bits has a total of 10 bits. Setting the M bit configures the SCI for nine-bit data characters. A frame
with nine data bits has a total of 11 bits
When the SCI is configured for 9-bit data characters, 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.
Table 13-9. Example of 9-Bit Data Formats
Table 13-8. Example of 8-Bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
18 0 0 1
17 0 1 1
17 1
(1)
1. The address bit identifies the frame as an address character. See
Section 13.4.4.6, “Receiver Wakeup”.
01
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
19 0 0 1
18 0 1 1
18 1
(1)
1. The address bit identifies the frame as an address character. See
Section 13.4.4.6, “Receiver Wakeup”.
01
BIT 5
START
BIT
BIT 0 BIT 1
NEXT
STOP
BIT
START
BIT
9-BIT DATA FORMAT
BIT 2 BIT 3 BIT 4 BIT 6 BIT 7
PARITY
OR DATA
BIT
PARITY
OR DATA
BIT
BIT M IN SCICR1 SET
8-BIT DATA FORMAT
BIT M IN SCICR1 CLEAR
BIT 5BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 6 BIT 7
BIT 8
STOP
BIT
NEXT
START
BIT
START
BIT