Texas Instruments MSC1210 manual Burnout Current Sources, Msb

Burnout Current Sources

12.4 Burnout Current Sources

When the Burnout bit (BOD) is set in the ADC control register (ADCON0.6), two current sources are enabled that source approximately 2∝A.

This allows for the detection of an open circuit (full-scale reading) or short-cir- cuit (0V differential reading) on the selected input differential pair.

The following program illustrates a simple open-circuit and short-circuit detec- tion routine.

#include <REG1210.H> #include <stdio.h> #include <stdlib.h> #include <math.h> #define LSB 298.0232e−9 extern void autobaud(void); extern long bipolar(void); void main(void)

{

float sample, decimation = 1728; CKCON = 0; // 0 MOVX cycle stretch autobaud();

printf(”Brown−Out Detection\n”); //Timer Setup

USEC= 10; // 11MHz Clock

ACLK = 9; // ACLK = 11,0592,000/10 = 1,105,920 Hz

//modclock = 1,105,920/64 = 17,280 Hz

//Setup ADC

PDCON &= 0x0f7; //turn on adc

ADMUX = 0x01;

ADCON0 = 0x70; // Vref On, Vref Hi, Buff off, BOD on, PGA=1

ADCON2	= decimation & 0xFF;	//	LSB	of	decimation
ADCON3	=(decimation>>8) & 0x07;	//	MSB	of	decimation

ADCON1 = 0x01; // bipolar, auto, self calibration, offset, gain while(1)

{

while (!(AIE & 0x20));

sample = bipolar() * LSB; // This read clears ADCIRQ printf (”Sample=%f”, sample);

if(sample < 0.01)

printf(” Short Circuit\n”); else if(sample > 2.4)

printf(” Open Circuit\n”); else

printf(“Normal Sensor Range\n”); while(!RI);

RI = 0;

}// while } //main

Analog-to-Digital Converter 12-7