
Chapter 11 Serial Communication Interface (S12SCIV5)
MC9S12XDP512 Data Sheet, Rev. 2.17
Freescale Semiconductor
495
11.4.3
Data Format
The SCI uses the standard NRZ mark/space data format. When Infrared is enabled, the SCI uses RZI data
format where zeroes are represented by light pulses and ones remain low. See
Figure 11-15
below.
Figure 11-15. 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.
ClearingtheMbitinSCIcontrolregister1configurestheSCIfor8-bitdatacharacters.Aframewitheight
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 11-13. Example of 8-Bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
1
1
1
8
7
7
0
0
1
1
0
1
0
1
1
1
1
The address bit identifies the frame as an address
character. See
Section 11.4.6.6, “Receiver Wakeup”
.
Table 11-14. Example of 9-Bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
1
1
1
9
8
8
0
0
1
1
0
1
0
1
1
1
Bit 5
Start
Bit
Bit 0
Bit 1
Next
Start
Bit
STOP
Bit
8-Bit Data Format
(Bit M in SCICR1 Clear)
Start
Bit
Bit 0
NEXT
START
Bit
STOP
Bit
9-Bit Data Format
(Bit M in SCICR1 Set)
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
Bit 2
Bit 3
Bit 4
Bit 6
Bit 7
POSSIBLE
PARITY
Bit
Possible
Parity
Bit
Standard
SCI Data
Infrared
SCI Data
Standard
SCI Data
Infrared
SCI Data