The Serial Communication Interface (SCI) MC9S12-C32

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The Serial Communication Interface
(SCI)MC9S12-C32

• Lecture L4.9

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Reference
HCS12 Serial Communications Interface (SCI) Block
Guide V02.08
S12SCIV2.pdf
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PIM_9C32 Block Diagram
SCI module
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SCI

• Asynchronous Serial I/O
• The 68HCS12 SCI Interface
• Programming the SCI
• SCI Interface Using Interrupts

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SCI

• Asynchronous Serial I/O
• The 68HCS12 SCI Interface
• Programming the SCI
• SCI Interface Using Interrupts

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SCI

• Asynchronous Serial I/O
• The 68HCS12 SCI Interface
• Programming the SCI
• SCI Interface Using Interrupts

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sci.asm
SCI0 SC0BDH EQU C8 baud rate
control SC0CR1 EQU CA SCI control reg
1 SC0CR2 EQU CB SCI control reg
2 SC0SR1 EQU CC SCI status reg SC0DRL
EQU CF SCI data reg RDRF EQU 20
SCSR mask INITIALIZE SCI sci0_init
CLR SC0CR1 8 bit LDD
52 STD SC0BDH 9600 baud LDAA
0C STAA SC0CR2 enable tx rx
RTS
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INPUT BYTE FROM SERIAL PORT INTO
A INCHAR LDAA SC0SR1 check
status ANDA RDRF check rdrf BEQ
INCHAR wait for char LDAA SC0DRL
get char in A RTS OUTPUT BYTE
IN A TO SERIAL PORT OUTPUT TST
SC0SR1 BPL OUTPUT loop until
tdre STAA SC0DRL send A RTS
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Communicating with a PC
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sciecho.asm
echo char to PC org 4000 sci_echo bsr sci0_i
nit se1 bsr inchar bsr output bra se1 include
sci.asm
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SCI

• Asynchronous Serial I/O
• The 68HCS12 SCI Interface
• Programming the SCI
• SCI Interface Using Interrupts

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SCI Interface using interrupts File
SCIINT.WHP display characters from PC keyboard
on LCD display SC0BDH EQU C8 baud
rate control SC0CR1 EQU CA SCI
control reg 1 SC0CR2 EQU CB SCI
control reg 2 SC0SR1 EQU CC SCI
status reg SC0DRL EQU CF SCI data
reg RDRF EQU 20 SCSR
mask SCI0.IVEC EQU 0FD8 SCI0 user vector
address 2 ORG 4000 main jsr spi_init initia
lize spi jsr lcd_init initialize
lcd jsr initq initialize queue jsr sci0_init
initialize sci mn1 jsr checkq if queue is
empty bcs mn1 wait jsr data8 store char
on LCD ldy 3 jsr ms_delay delay 10
ms bra mn1
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INITIALIZE SCI sci0_init SEI
disable interrupts CLR SC0CR1 8
bit LDD 52 STD SC0BDH 9600
baud LDAA 2C STAA SC0CR2
enable tx rx, RX INT LDD SCI_INTSER STD
SCI0.IVEC set sci int vector CLI
enable interrupts RTS
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Interrupt service routine get char and store
in queue  SCI_INTSER LDAA SC0SR1 ANDA RDRF
BEQ SI1 if RDRF set LDAA SC0DRL read data
(clears RDRF flag) JSR QSTORE and store it in
queue SI1 RTI INCLUDE QUEUE.ASM INCLUDE
LCD.ASM