1. The Serial Communication Interface (SCI) MC9S12-C32
Lecture L4.9

2. HCS12 Serial Communications Interface
Reference
HCS12 Serial Communications Interface
(SCI)
Block Guide
V02.08
S12SCIV2.pdf

3. PIM_9C32
Block Diagram
SCI module

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

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

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

16. 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 $ ;SCSR mask
; INITIALIZE SCI
sci0_init
CLR SC0CR ;8 bit
LDD #52
STD SC0BDH ;9600 baud
LDAA #$0C
STAA SC0CR ;enable tx & rx
RTS

17. ; INPUT BYTE FROM SERIAL PORT INTO A
INCHAR
LDAA SC0SR ;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

18. Communicating with a PC

19. sciecho.asm ; echo char to PC org $4000 sci_echo bsr sci0_init
se1 bsr inchar
bsr output
bra se1
#include sci.asm

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

21. ; 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 $ ;SCSR mask
SCI0.IVEC EQU $0FD8 ;SCI0 user vector address + 2
ORG $4000
main
jsr spi_init ;initialize 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

22. ; INITIALIZE SCI
sci0_init
SEI ;disable interrupts
CLR SC0CR ;8 bit
LDD #52
STD SC0BDH ;9600 baud
LDAA #$2C
STAA SC0CR ;enable tx & rx, RX INT
LDD #SCI_INTSER
STD SCI0.IVEC ;set sci int vector
CLI ;enable interrupts
RTS

23. ; 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