Texas Instruments MSP50C6xx, User Manual

Page: 350 / 390

C– – Efficiency
5-54
Descriptions of files that are also in Project 2 have been omitted.
[lcd] Directory holding files for writing to an LCD screen.
lcd.asm Routines for writing to an LCD screen.
lcd.irx Mnemonics used by lcd.asm.
lcd_ram.irx Allocates RAM for lcd.asm.
The only changes to the assembly are in mainasm.asm and in cmm1.asm. In
mainasm.asm, two calls are made to setup and initialize the lcd. To allow this,
the labels for the routines were declared external.
external lcd_setio
external lcd_init
In _goasm, they are then called to initialize the LCD before it is used.
; set up the LCD
call lcd_setio
call lcd_init
In cmm1.asm, simple routines for writing characters and numbers were
added, along with routines to bring the cursor to the beginning of the first and
second row.
_writeNum
mov a0, *r7 – 2
call
lcd_wrbcd2
ret
_writeCharacter
mov a0, *r7 – 2
call
lcdwchr
ret
_rowZero
call lcd_row0
ret
_rowOne
call lcd_row1
ret
_writeNum and _writeCharacter get a value to write from the stack and then
call routines in lcd.asm. _rowZero and _rowOne simply call routines in
lcd.asm.
main.cmm has been modified by the addition of a function, showTime().
/************************************************
/ Display the time on the LCD
************************************************/
cmm_func showTime(){
int temp;
rowZero();
writeNum(time[WIDTH*0+0]); //hours
writeCharacter(’:’);
writeNum(time[WIDTH*0+1]); //minutes