MSP430FR2422: Reconfigure an analog pin as Digital pin

Maunik Patel

Hello,

In our application, we need to wake-up the MCU when there is a signal on pin P1.1 & then measure the voltage present on the same pin.

For this, we have followed below approach.

configure Pin P1.1 as digital i/p pin
- enable interrupt for the same
- go to sleep mode (LPM0)
upon wake-up, by interrupt on P1.1, reconfigure this pin as analog i/p channel A1
calculate voltage on P1.1 using ADC & do other tasks
Go to Point - 1

But, it doesn't work.
MCU wakes-up & performs the voltage calculation task, when interrupted on the pin P1.1 for the first time only.
After that, MCU doesn't generate interrupt on pin P1.1.

Can anyone help us to resolve this issue?
If there is an alternate approach to fulfill our application requirement, please share it with us.

Thank You

over 6 years ago

0 Ling Zhu2 over 6 years ago

TI__Genius 9570 points

Hi Maunik,

Make sure P1.1 is reconfigured as digital input pin and enable the interrupt.

Can you share your source code?

Ling

0 Maunik Patel over 6 years ago in reply to Ling Zhu2

Prodigy 40 points

Hi Ling,

Please find the code below.

#include <msp430.h>

void config_wakeup_pin(void);
void config_analog_pin(void);

void main (void)
{
    WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer

    // Configure LED Pin (P2.2) as output pin
    P2DIR |= BIT2;                            // Set P2.2 to output direction
    P2OUT &= ~BIT2;

    // configure IO1 Pin (analog input pin P1.1) as digital input, just before entering sleep mode
    // in active mode we'll configure this pin as analog input pin
    config_wakeup_pin();

    PM5CTL0 &= ~LOCKLPM5;                   // Disable the GPIO power-on default high-impedance mode
    __bis_SR_register(LPM0_bits | GIE);          // Enter LPM0 w/ interrupt

    while(1)
    {
        config_analog_pin();
 
	/*
	*	other operations
	*/

        config_wakeup_pin();
        __bis_SR_register(LPM0_bits | GIE);          // Enter LPM0 w/ interrupt
        __no_operation();                     // Placeholder for while loop (not required)
    }
}

// Port 1 interrupt service routine
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
    switch( __even_in_range( P1IV, P1IV_P1IFG7 )) {
        case P1IV_P1IFG1:                                       // Pin 1.1
            __bic_SR_register_on_exit(LPM0_bits);              // Clear CPUOFF bit from LPM0
            break;
        default:   _never_executed();
    }
}

void config_wakeup_pin(void)
{
    P1REN |= BIT1;                            // Enable P1.1 internal resistance
    P1OUT &= ~BIT1;                            // Set P1.1 as pull-Up resistance
    P1IES &= ~BIT1;                           // P1.1 Lo/Hi edge
    P1IFG &= ~BIT1;                           // P1.1 IFG cleared
    P1IE |= BIT1;                             // P1.1 interrupt enabled
}
void config_analog_pin(void)
{
    // Configure ADC A1 pin
    SYSCFG2 |= ADCPCTL1;
    SYSCFG2 |= ADCPCTL0 | ADCPCTL2;	    // we are using External reference voltage for ADC
    

    // Disable the GPIO power-on default high-impedance mode to activate
    // previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;

    // Configure ADC10
    ADCCTL0 |= ADCSHT_2 | ADCON;                              // ADCON, S&H=16 ADC clks
    ADCCTL1 |= ADCSHP;                                        // ADCCLK = MODOSC; sampling timer
    ADCCTL2 |= ADCRES_1;                                        // 10-bit conversion results
    ADCMCTL0 |= ADCINCH_1;                        // A1 ADC input select
    ADCMCTL0 |= ADCSREF_7;                        // Vref= external voltage

    // Configure reference
    PMMCTL0_H = PMMPW_H;                                      // Unlock the PMM registers
    PMMCTL2 |= EXTREFEN;                                      // Enable external reference
    __delay_cycles(400);                                      // Delay for reference settling
}

0 Ling Zhu2 over 6 years ago in reply to Maunik Patel

TI__Genius 9570 points

#include <msp430.h>

void config_wakeup_pin(void);
void config_analog_pin(void);

void main (void)
{
    WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer

    // Configure LED Pin (P2.2) as output pin
    P2DIR |= BIT2;                            // Set P2.2 to output direction
    P2OUT &= ~BIT2;

    // configure IO1 Pin (analog input pin P1.1) as digital input, just before entering sleep mode
    // in active mode we'll configure this pin as analog input pin
    config_wakeup_pin();

    PM5CTL0 &= ~LOCKLPM5;                   // Disable the GPIO power-on default high-impedance mode
    __bis_SR_register(LPM0_bits | GIE);          // Enter LPM0 w/ interrupt

    while(1)
    {
        config_analog_pin();

        /*
         *   other operations
         */

        config_wakeup_pin();
        __bis_SR_register(LPM0_bits | GIE);          // Enter LPM0 w/ interrupt
        __no_operation();                     // Placeholder for while loop (not required)
    }
}

// Port 1 interrupt service routine
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
    switch( __even_in_range( P1IV, P1IV_P1IFG7 )) {
    case P1IV_P1IFG1:                                       // Pin 1.1
        P2OUT ^= BIT2;                                      //Toggle LED
        __bic_SR_register_on_exit(LPM0_bits);               // Clear CPUOFF bit from LPM0
        break;
    default:   _never_executed();
    }
}

void config_wakeup_pin(void)
{
    PMMCTL0_H = PMMPW_H;                                      // Unlock the PMM registers
    PMMCTL2 &= ~EXTREFEN;                                     // Disable external reference

    SYSCFG2 &= ~ADCPCTL1;

    P1REN |= BIT1;                            // Enable P1.1 internal resistance
    P1OUT &= ~BIT1;                           // Set P1.1 as pull-down resistance
    P1IES &= ~BIT1;                           // P1.1 Lo/Hi edge
    P1IFG &= ~BIT1;                           // P1.1 IFG cleared
    P1IE |= BIT1;                             // P1.1 interrupt enabled

}
void config_analog_pin(void)
{
    // Configure ADC A1 pin
    SYSCFG2 |= ADCPCTL1;
    SYSCFG2 |= ADCPCTL0 | ADCPCTL2;     // we are using External reference voltage for ADC

    // Configure ADC10
    ADCCTL0 |= ADCSHT_2 | ADCON;                                // ADCON, S&H=16 ADC clks
    ADCCTL1 |= ADCSHP;                                          // ADCCLK = MODOSC; sampling timer
    ADCCTL2 |= ADCRES_1;                                        // 10-bit conversion results
    ADCMCTL0 |= ADCINCH_1;                                      // A1 ADC input select
    ADCMCTL0 |= ADCSREF_7;                                      // Vref= external voltage

    // Configure reference
    PMMCTL0_H = PMMPW_H;                                      // Unlock the PMM registers
    PMMCTL2 |= EXTREFEN;                                      // Enable external reference
    __delay_cycles(400);                                    // Delay for reference settling
}

0 Maunik Patel over 6 years ago in reply to Ling Zhu2

Prodigy 40 points

Hi Ling,

You resolved my issue & the code is working fine now.

Thanks for resolving my issue.
Thanks a lot.

Regards,
Maunik Patel

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MSP430FR2422: Reconfigure an analog pin as Digital pin