Part Number:MSP430F6736
Hi
i am using the ADC10 to monitor the voltage from a battery on AuxVcc3.
So long as the battery voltage is above about 1.6V i get a reading.
However, once i start dropping the battery voltage (the 'battery' is a variable power supply) below 1.6V the conversion doesn't happen and the watchdog timer is triggered.
Its almost as if the ADC10 itself is being powered from the AuxVcc3 line.....is it???
These are my settings:
AUXADCCTL |= AUXADCSEL_3 | AUXADCR_0 ; // select auxVcc3 as input to ADC10. 18Kohm load resistance
AUXADCCTL |= AUXADC; // switch on the aux supply input to ADC10
use internal ADC osc with pulse sample mode
use 32clks for sample & hold time
single conversion
get result in interrupt.
ADC10CTL0 = ADC10SHT_3 | ADC10ON; // S&H=32 ADC clks, Enable ADC10 but keep ADC10ENC = 0
ADC10CTL1 = 0 | ADC10SHP | 0 | 0 | ADC10SSEL_0 | ADC10CONSEQ_0; // s/w trig, pulse sample mode, no inversion, no clk div, modclk, single ch/conv
ADC10CTL2 = ADC10RES; // no predivision, 10-bit conversion results, unsigned result, no reduction in sampling rate
ADC10MCTL0 = ADC10SREF_0 | ADC10INCH_12; // Ref=AVcc & AVss, channel 12 is Aux supply input...NOT 11!
ADC10IE |= ADC10IE0 | ADC10TOVIE; // Enable ADC conversion complete interrupt
ADC10CTL0 |= ADC10ENC | ADC10SC; // Sampling and conversion start
what am i doing wrong??
thanks in advance.