Task-Specific Program Code
C-20
Example C–13. Synchronous Serial Port Continuous Mode Transmission (ssp.asm)
* File: ssp.asm *
* Function: Continuous transmit in CONTINUOUS mode *
* Internal shift clock and frame sync *
* Transmit FIFO level is set to 4 *
.title ”SSP Continuous mode” ; Title
.copy ”init.h” ; Variable and register declaration
.copy ”vector.h” ; Vector label declaration
.text
start: clrc cnf ; Map block B0 to data memory
ldp #0h ; set DP=0
setc INTM ; Disable all interrupts
splk #0000h, 60h ; Set zero wait states
out 60h, wsgr
splk #0cc0ch,60h ; reset the serial port by writing
out 60h, sspcr ; zeros at NOR/RES
splk #0cc3ch,60h ; enable Sync port, 4 word fifo,
out 60h,sspcr ; internal clocks, Continuous mode
; Use sspcr= #0cc3eh for Burst mode
splk #1717h,61h ; dummy data for tx
splk #7171h,63h
splk #0aa55h,64h
splk #55aah,62h ; transmit 55aah on tx
splk #10h,imr ; enable xinit interrupt
clrc intm ; enable INTM
out 62h,sdtr ; Xmit once to start
out 61h,sdtr ; transmit interrupts
out 63h,sdtr
out 64h,sdtr
loop: clrc xf ; clear xf flag
idle
b loop
codtx: setc xf ; set xf bit
out 62h,sdtr ; transmit 0x55aah again
out 61h,sdtr ; transmit 1717h
out 63h,sdtr ; transmit 7171h
out 64h,sdtr ; transmit aa55h
splk #0010h, ifr ; clear ifr flag
clrc intm
ret
codrx: ret
inpt1: ret
inpt23: ret
timer: ret
uart: ret
.end ; Assembler module end directive
; –optional
