Analog-to-Digital Converter - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 623

unsigned int quo,rem,frem;

long temp;

char *ptr,fdigit;

delayby100ms(2); /* wait for LCD kit to self-initialize */

openlcd(); /* configure LCD kit */

openAD0(); /* configure AD0 module */

cmd2lcd(0x80); /* set cursor to upper left corner */

puts2lcd(msg1); /* output the message “humidity 5 ” */

while(1) {

ATD0CTL5 5 0x87; /* start a conversion with result right-justified */

while(!(ATD0STAT0&SCF)); /* wait until conversion is done */

temp 5 (long)ATD0DR0 * 100; /* force compiler to use 32-bit to represent the product */

quo 5 temp/1023; /* integer part of temperature */

rem 5 temp % 1023; /* remainder part */

if (quo 55 100)

rem 5 0; /* force highest humidity to 100% only */

fdigit 5 (rem * 10)/1023; /* compute the fractional digit */

frem 5 (rem * 10) % 1023;

if (frem . 511)

fdigit 11 ;

if (fdigit 55 10) { /* round off the fractional digit */

fdigit 5 0;

quo 11 ;

}

ptr 5 &buf[0];

int2alpha(quo,ptr); /* convert the integer part to ASCII string */

ptr 5 &buf[0];

while(*ptr) /* find the end of the integer string */

ptr 11 ;

*ptr 11 5 '.'; /* decimal point */

*ptr 11 5 fdigit 1 0x30; /* fractional digit */

*ptr 11 5 '%';

*ptr 5 0; /* terminate the humidity string */

cmd2lcd(0xC0); /* move cursor to 2nd row */

puts2lcd(blanks); /* clear the 2nd row */

cmd2lcd(0xC5); /* set cursor to column 5 row 2 */

puts2lcd(&buf[0]); /* output the humidity */

delayby100ms(2); /* wait for 0.2 s */

}
}
void openAD0(void)
{
ATD0CTL2 5 0xE0; /* enable AD0, fast ATD flag clear, power-down on wait */

ATD0CTL3 5 0x0A; /* perform one ATD conversion */

ATD0CTL4 5 0x25; /* prescaler set to 12, select four cycles sample time */

delayby10us(2);
}

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