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Task-Specific Program Code
C-18
Example C–12. Testing and Using Asynchronous Serial Port Delta Interrupts (bitio.asm)
* File: bitio.asm *
* Function: Delta interrupt test code *
* Accepts delta interrupt on IO pins 3 and 2 *
* If bit level changes on bit 7, send character ’c’ *
* through UART & toggle xf pin. *
* If bit level changes on bit 6, send character ’i’ *
* through UART & toggle xf pin. *
* The delta bits are cleared after interrupt service *
.title ”BIT IO Interrupt Test” ; 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
* UART initialization *
splk #0ffffh,ifr ; clear interrupts
splk #0000h,60h
out 60h, wsgr ; Set zero wait states
splk #0c200h,61h ; reset the UART by writing 0
out 61h, aspcr ; 1 stop bit, Delta interrupt,
; input i/o
splk #0e200h,61h
out 61h,aspcr
splk #4fffh,62h
out 62h,iosr ; disable auto baud
splk #0411h, 63h ; set baud rate =1200 @ 20-MHz CLKOUT1
out 63h, brd
splk #20h,imr ; enable UART interrupt
splk #0063h,65h ; transmit value = 0063h =’c’
splk #0069h,67h ; transmit value = 0063h =’i’
mar *,ar1
lar ar1,#rxbuf
* Load data at DM300 *
lar ar1,#rxbuf
lar ar0, #size ; load buffer size
mar *,ar1 ; load data pointer
clrc intm ; disable interrupts for polling
wait:
idle
b wait