Texas Instruments MSP50C6xx - Manual (Page 359)

Initializing the MSP50C6xx
6-5 Applications
6.2.1 File init.asm
;****************************************************************
; INIT.ASM
;
; Revision 1.04
;
; Modified from revision 1.03: if not CRO, we check port 0x2F
; to distinguish between P and
; C parts.
;
; Turn off TIMER 2 rather than leave it running.
;
; Modified to cope with 6 bit trim value. Top 5 bits go to bits
; 15–11 in ClkSpdCtrl, LSB of trim goes to bit 9 in ClkSpdCtrl.
;
; A fairly basic but compact initialization routine for the 614.
; This sets the 614 to run at 8 MHz, 10 bit DAC at 8 kHz.
;
; Geoff Martindale, BP
; May 2000
;****************************************************************
;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
;!!!!!!!!!!!!!!!!!!!!!! WARNING !!!!!!!!!!!!!!!!!!!!!!!!!!!
;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
;! FOR RESISTOR TRIM USERS:
;! DO NOT WRITE TO PORT G PRIOR TO READING THE RTRIM VALUE!
;! THIS PRESERVES THE ZERO VALUE AT PORT 0x2F WHEN READING THE
;! TRIM VALUE (should be zero if P part, should be non–zero if
;! C part).
;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
;!!!!!!!!!!!!!!!!!!!!!! WARNING !!!!!!!!!!!!!!!!!!!!!!!!!!!
;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
;****************************************************************
; Start off by clearing all the RAM (and tags) and then zero
; every register. The status register (STAT) must be cleared
; immediately upon power up.
;****************************************************************
init614
zac a0 ;clear a0
mov *0x001,a0 ;clear second RAM location, leave first for C––
mov STAT,*0x001 ;clear status register
mov STR,32–2 ;set string register to loop 32 times
zacs a0 ;clear all accumulators
out IFR,a0 ;clear pending interrupts
out IntGenCtrl,a0 ;clear all interrupt mask bits, disable timers
mov r0,0x000 ;point to beginning of RAM
mov r4,RAM_SIZE – 2 ;do a loop RAM_SIZE times
BEGLOOP
rtag
*r0 ;reset tag
mov *r0++,a0 ;clear the RAM
ENDLOOP
mov STR,0 ;clear string register