1. The Serial Peripheral Interface (SPI)
Lecture L4.5

2. Reference
SPI
Block Guide
V03.06
S12SPIV3.pdf

3. PIM_9C32
Block Diagram
SPI module

7. $DA

10. $D8

11. $D8

14. $D8

15. $D9

16. $D9

17. $DB

18. $DB

19. Liquid Crystal Display

20. Relationship between RS, R/W, and E

22. CLM912C32
LCD PORT
4-bit SPI
Interface
Write only

24. File: spi.asm ; Serial Peripheral Interface SPI0
SPI0CR equ 00D8 ; SPI Control Register 1
SPI0CR equ 00D9 ; SPI Control Register 1
SPI0BR equ 00DA ; SPI Baud Rate Register
SPI0SR equ 00DB ; SPI Status Register
SP0DR equ 00DD ; SPI Data Register
spi_init ; Initialize SPI port
ldaa #$10
staa SPI0CR2 ; enable /SS
clr SPI0BR ; 4 MHz (/2)
ldaa #$52
staa SPI0CR1 ; CPHA = 0, CPO; = 0
rts

25. File: spi.asm (cont.) ; send A out spi send_spi psha ; save A
ss0 ldaa SPI0SR
anda #$20
beq ss0 ; wait for trans. buff empty
pula ; get A
psha ; save it again
staa SP0DR ; send char
ss1 ldaa SPI0SR
anda #$80
beq ss1 ; wait till sent
ldaa SP0DR ; clear SPIF
pula ; restore A
rts

26. SPI0CR1
$D8

27. ; LCD for Axiom CML9S12-C32
#include hex2asc.asm
#include spi.asm
#include ms_delay.asm
; Write 4-bit instruction in A
instr4
psha ;save A
anda #$0f
jsr send_spi ;EN LO, RS LO
oraa #$80 ;EN HI
jsr send_spi
pula ;get A
jsr send_spi ;EN LO
pula ;restore A
rts

28. ; Write 8-bit instruction in A
psha ;save A
lsra
bsr instr4 ;send hi nibble
pula ;get A
bsr instr4 ;send lo nibble
rts

29. ; Write 4-bit data in A
data4
psha ;save A
anda #$0f
oraa #$40 ;EN HI
jsr send_spi ;EN LO, RS HI
pula ;get A
oraa #$C0 ;EN HI
jsr send_spi
psha
oraa #$40
jsr send_spi ;EN LO
pula
pula ;restore A
rts

30. ; Write 8-bit data in A
data8
psha ;save A
lsra
bsr data4 ;send hi nibble
pula ;get A
bsr data4 ;send lo nibble
rts 

31. ; Initialize 4-bit wide
lcd_init
ldy #50
jsr ms_delay
ldaa #3
jsr instr4 ; function set
ldaa #2
ldaa #$2C
jsr instr8 ; 4-bits, 2 lines
ldy #10
ldaa #$06
jsr instr8 ; inc cursor
ldaa #$0f
jsr instr8 ; display on
ldaa #$01
jsr instr8 ; clear display
ldy #20
ldaa #$80
jsr instr8 ; set addr to 0
ldaa #$00
jsr send_spi ; turn off all signals
rts

32. clear_lcd
ldaa #1
jsr instr8
ldy #10
jsr ms_delay
rts
; display hex value in A on LCD 
hex2lcd
jsr hex2asc ;convert to ascii
jsr data8 ;display it
; display asciiz string on LCD
; X -> asciiz string 
type_lcd
ldaa 1,x+ ;get next char
beq done ;if null, quit
jsr data8 ;else display it
ldy #10
jsr ms_delay ; delay 10 ms
bra type_lcd ;and repeat
done rts

33. ; lcdtest.asm
org $800
mess1 db 'Haskell',0
org $4000
main
jsr spi_init
jsr lcd_init
ldx #mess1
jsr type_lcd
swi
#include lcd.asm

34. 1: ; lcdtest.asm 2:
3: = org $800
4: B 65 6C mess1 db 'Haskell',0
0806 6C 00 5:
6: = org $4000 7:
8: main
9: jsr spi_init
10: jsr lcd_init
11: CE ldx #mess1
12: A jsr type_lcd
13: C 3F swi

35. 16 x 1
Hex Keypad