Msp430f5438a: adc12 problem

>This message appeara when the program is running and i connect the voltage to the pin.
Please specify voltage and impedance of the source.

In a first moment, I connected an arduino pin to the adc port directly without impedance.
After, a variable source 0-3.3 volts from a pointer of 10 k potentiometer.

Hi Miguel!

I'm not 100% sure about the following because I never used an Arduino, but doesn't the Arduino work with 5V? If you connected 5V to the MSP430 without having any resistance in between, then maybe you already killed the pin by overvoltage and the resulting excessive current through the protection diode?

Dennis

First of all, Thanks for the help.

I don't know the reason, but now it works correctly with the same performance. 

Other quick question, do you know why the ADCMEM0 register is different to 0 if there is not any voltage at this pin in the beginning?

My code is the following:

#include <msp430.h>
int temp=0;
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
ADC12CTL0 = ADC12SHT02 + ADC12ON; // Sampling time, ADC12 on
ADC12CTL1 = ADC12SHP; // Use sampling timer
ADC12IE = 0x01; // Enable interrupt
ADC12MCTL0 |= ADC12INCH_7;
ADC12CTL0 |= ADC12ENC;

P6SEL |= 0x80; // P7.4 ADC option select
P1DIR |= BIT0; // P1.0 output

__delay_cycles(10000);

while (1)
{
ADC12CTL0 |= ADC12SC; // Start sampling/conversion

__bis_SR_register(LPM0_bits + GIE); // LPM0, ADC12_ISR will force exit
__no_operation(); // For debugger
}
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = ADC12_VECTOR
__interrupt void ADC12_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(ADC12_VECTOR))) ADC12_ISR (void)
#else
#error Compiler not supported!
#endif
{
switch(__even_in_range(ADC12IV,34))
{
case 0: break; // Vector 0: No interrupt
case 2: break; // Vector 2: ADC overflow
case 4: break; // Vector 4: ADC timing overflow
case 6: // Vector 6: ADC12IFG0
temp = ADC12MEM0;
if (ADC12MEM0 >= 0x7ff) // ADC12MEM = A0 > 0.5AVcc?
P1OUT |= BIT0; // P1.0 = 1
else
P1OUT &= ~BIT0; // P1.0 = 0

__bic_SR_register_on_exit(LPM0_bits); // Exit active CPU

break;
case 8: break; // Vector 8: ADC12IFG1
case 10: break; // Vector 10: ADC12IFG2
case 12: break; // Vector 12: ADC12IFG3
case 14: break; // Vector 14: ADC12IFG4
case 16: break; // Vector 16: ADC12IFG5
case 18: break; // Vector 18: ADC12IFG6
case 20: // Vector 20: ADC12IFG7
break;
case 22: break; // Vector 22: ADC12IFG8
case 24: break; // Vector 24: ADC12IFG9
case 26: break; // Vector 26: ADC12IFG10
case 28: break; // Vector 28: ADC12IFG11
case 30: break; // Vector 30: ADC12IFG12
case 32: break; // Vector 32: ADC12IFG13
case 34: break; // Vector 34: ADC12IFG14
default: break;
}
}

It is an example from texas.

Thanks