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MSP430G2553: MSP430 ADC

MUKHRAMUDDIN MOHAMMED
Prodigy 200 points
Part Number: MSP430G2553
Other Parts Discussed in Thread: MSP430G2253, , MSP430WARE

Hello,

     My project has two Analog outputs. I am using MSP430G2253 Microcontroller to do two ADC conversions. I am not getting correct ADC conversion values . Will you Please help me.

Code:

void main()

{

xxxxxxxxxx

xxxxxxxx

xxxxxxxxx

while(1)

{

adc_temp();

calc_temp();

__delay_cycles(50000);

adc_signal();

calc_value();

__delay_cycles(50000);

}

}

void adc_temp()
{
ADC10CTL0 &= ~ENC;
ADC10CTL0 = ADC10ON + ADC10SR + ADC10SHT_0 + SREF_0;
ADC10CTL1 = CONSEQ_0 + ADC10SSEL_0 + ADC10DIV_0 + SHS_0 + INCH_4;
ADC10CTL0 |= ENC;
}

void adc_signal()
{
ADC10CTL0 &= ~ENC;
ADC10CTL0 = ADC10ON + ADC10SR + ADC10SHT_0 + SREF_0;
ADC10CTL1 = CONSEQ_0 + ADC10SSEL_0 + ADC10DIV_0 + SHS_0 + INCH_5;
ADC10CTL0 |= ENC;
}

calc_temp()

{

ADC10CTL0 |= ENC + ADC10SC;
temp_value = ADC10MEM;
__delay_cycles(5000);

xxxxxxxxx;

xxxxxxxxx

xxxxxxxxx

}

calc_value()

{

ADC10CTL0 |= ENC + ADC10SC;
signal_value = ADC10MEM;
__delay_cycles(5000);

xxxxxxxxx;

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}

  • 0
    TI__Guru 56685 points
    Hello Mukhramuddin,

    You may have to increase your sample and hold time for correct results. We do have example code available on how to sample the internal temp sensor using the ADC. Navigate to the TI Resource Explorer -> Software -> MSP430Ware -> Devices -> MSP430G2xx -> MSP430G2553 -> Peripheral Examples -> Register Level -> msp430g2x33_adc10_temp.c . TI Resource Explorer can be found within CCS or at dev.ti.com .
  • 0 in reply to Jace H
    Prodigy 200 points

    Hello Jace,

                  Thanks for the reply. I want to use two external ADC (may be three ADC in future).

     

  • 0 in reply to Jace H
    Prodigy 200 points
    Hello Jace,

    Thanks for the reply.

    P1.1 and P1.2 used for UART communincation

    P1.3, P1.4 and P1.5 for ADC conversions.


    Will you please let me know the mistakes in the code.

    Thanks.
  • 0 in reply to MUKHRAMUDDIN MOHAMMED
    Genius 4090 points

    In your functions,

    You are starting the ADC conversion, but reading the sample values even before the sampling & conversion is done.

    For a valid sampling & conversion either you have to use a busy wait loop or use ADC10 interrupt(ADC10IE).

    calc_temp() & calc_value(),

    follow as below,

    Busy wait Loop:

    calc_temp(){

ADC10CTL0 |= ENC + ADC10SC;

while (ADC10CTL1 & ADC10BUSY);

temp_value = ADC10MEM;

__delay_cycles(5000); //This is not necessary unless you are using it for something else than ADC purpose

}

    Or

    Interrupt:

    init(){

;

;

ADC10CTL1 |= <ADC input channel>;

ADC10AE0 |= <Analog enable>

;

;

}

calc_temp(){

ADC10CTL0 |= ADC10IE;//enable ADC interrupt

ADC10CTL0 |= ENC + ADC10SC;

<CPU sleep>

}

__interrupt void ADC10_ISR(void)

{

temp_value = ADC10MEM;

<wakeup CPU>

}

    About your comment "P1.1 and P1.2 used for UART communincation",

    You can reconfigure these channels through PxSEL & PxSEL2 registers.

  • 0 in reply to chethu gowda
    Prodigy 200 points
    Hi Chethu,

    Thanks for the reply and information. I will try this today. Thank you.

    Thanks and Regards,
    M.Mohammed

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