Hardware Reference
In-Depth Information
rem
5
temp % 753;
/* remainder part */
fdigit
5
(rem * 10)/753;
/* compute the fractional digit */
frem
5
(rem * 10) % 753;
if (frem
.
377)
fdigit
11
;
if (fdigit
55
10) {
/* round off the fractional digit */
fdigit
5
0;
quo
11
;
}
ptr
5
&buf[0];
quo
5
quo
1
948;
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
'.';
*ptr
11
5
fdigit
1
0x30;
*ptr
11
5
0x20;
*ptr
11
5
'm';
*ptr
11
5
'b';
*ptr
11
5
'a';
*ptr
11
5
'r';
*ptr
5
0;
/* terminate the barometric pressure 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 pressure */
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);
}
▲
A data acquisition system consists of four major components: a transducer, a signal-
conditioning circuit, an ADC, and a computer. The transducer converts a nonelectric quantity
into a voltage. The transducer output may not be appropriate for processing by the ADC. The
signal-conditioning circuit shifts and scales the output from a transducer to a range that can
take advantage of the full capability of the ADC. The ADC converts an electric voltage into a
digital value that will be further processed by the computer.
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