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Chapter 15 Serial Communication Interface (S12MC9S12XDP512V5)
MC9S12XDP512 Data Sheet, Rev. 2.11
690 Freescale Semiconductor
15.4.3 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 15-15 below.
Figure 15-15. 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.
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 15-14. Example of 8-Bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
18001
17011
17 1
1
1
The address bit identifies the frame as an address
character. See Section 15.4.6.6, “Receiver Wakeup”.
01
Table 15-15. Example of 9-Bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
19001
18011
18 1
1
1
The address bit identifies the frame as an address
character. See Section 15.4.6.6, “Receiver Wakeup”.
01
Bit 5
Start
Bit
Bit 0 Bit 1
Next
STOP
Bit
Start
Bit
8-Bit Data Format
(Bit M in SCICR1 Clear)
Start
Bit
Bit 0
NEXT
STOP
Bit
START
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