ST ST7 - Page 213

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7 - Debugger and PROM Programmer Tutorial for ST72251
The source code for the main program and for the multitasking kernel follow. First, the main
program:
ST7/
;==================================================================
;= Demonstration of a simplified real-time cooperative kernel =
;==================================================================
; This program performs a voltage to frequency conversion on four
; independent channels.
; Pc0 through Pc3 are the analog inputs,
; Pa0 through Pa3 are the corresponding outputs (blinking led's).
; Declaration of the macro that provides the code for all tasks.
; =================
TASK MACRO Channel
LOCAL TaskLoop,InnerLoop,TaskCont
TaskLoop:
ld A,#{Channel-1} ; Pc0 analog input
call acana ; Convert voltage
ld X, adcdr
ld A, (TimingTable,X) ; Get result of timing function from
table
ld reg&Channel, A
InnerLoop:
ld A, reg&Channel
tnz A
jreq TaskCont ; Yield until timing register = 0
call Yield
jra InnerLoop
TaskCont:
ld A, #{1 SHL {Channel-1}}; When register is zero, toggle output
xor A, padr
ld padr, A
jra TaskLoop ; Continue looping for this task
MEND
#include "Register.inc"
EXTERN StartTasks, Yield, acana
PUBLIC watch, AddrTasks
; Constants
; ==========
cpudiv2.b EQU 0 ; CPU clock ratio 1/2
watch.b EQU $7F ; Watchdog reload value
t_timer.b EQU $14 ; 10 ms timer reload value
; Registers
; =========
Segment 'ram0'
reg1.b DS.B 1 ; Timing register 1
reg2.b DS.B 1 ; Timing register 2
reg3.b DS.B 1 ; Timing register 3
reg4.b DS.B 1 ; Timing register 4
Segment 'rom' ; set in ANACLMAP.ASM to E000h
Words
; Table of start adresses of each task