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MSP430FR5964: Toggle ADC/GPIO functionality

Itay Cohen
Intellectual 585 points
Part Number: MSP430FR5964

Hi,

I need to toggle P1.1 (A1) from ADC to GPIO after every sampling.

When I set P1SELC |= BIT1, just before I set ADC12CTL0 |= ADC12ENC | ADC12SC, the ADC is not working.

It works when I set P1SELC |= BIT1 at the beginning of the code (just before PM5CTL0 &= ~LOCKLPM5. But than I cannot change the GPIO functionality on the fly.

Any ideas?

Thanks,

Itay

  • 0
    Guru 91390 points

    In what way does it not work? The pin is actually always connected to the ADC, but if PSEL != 3 the Schmitt triggers are still engaged so the result is boring [Ref data sheet (SLASE54D) Fig 9-3].

    I count 5x Errata related to ADC operation [Ref Errata sheet (SLAZ682L) Sec 1]. Is it possible some other code (which you haven't shown) is tripping over one of these?

  • +1 in reply to Bruce McKenney47378
    Intellectual 585 points

    Hi,

    The solution was to add small delay between changing the port functional selection and start sampling:

    P1SELC |= BIT1; // Configure P1.1 for ADC
    __delay_cycles(500);
    ADC12CTL0 |= ADC12ENC | ADC12SC; // Start sampling/conversion

    Thanks,

    Itay

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