MSP432P401R: different values on ADC0 and ADC1

Jan Cumps

Part Number: MSP432P401R

I'm running the example ADC Project from the TI-RTOS Driver examples, and with the same dc signal applied to ADC0 (P5.5) and ADC1(P5.4) I get different values (ADC1 approx 35x lower result than ADC0)

A few examples:

Starting the ADC Single Channel example
System provider is set to SysMin.  Halt the target to view any SysMin contents in ROV.
ADC channel 0 initialized
ADC channel 0 convert result: 0x0
ADC channel 1 initialized
ADC channel 1 convert result (0): 0x0

Starting the ADC Single Channel example
System provider is set to SysMin.  Halt the target to view any SysMin contents in ROV.
ADC channel 0 initialized
ADC channel 0 convert result: 0x404
ADC channel 1 initialized
ADC channel 1 convert result (0): 0x15

Starting the ADC Single Channel example
System provider is set to SysMin.  Halt the target to view any SysMin contents in ROV.
ADC channel 0 initialized
ADC channel 0 convert result: 0xb89
ADC channel 1 initialized
ADC channel 1 convert result (0): 0x39

Is there something I'm missing?

over 8 years ago

0 Jan Cumps over 8 years ago

Guru 15740 points

as a heads-up, the board is ok.
I tested the non-TI-RTOS example adc14_multiple_channel_no_repeat, and ADC0 and 1 are ok there.
Is ADC Channel 0 and Channel 1 something different than ADC PIN A0 and A1 ?

0 Jan Cumps over 8 years ago in reply to Jan Cumps

Guru 15740 points

I found it.

They use a different reference in the example's (in their MSP_EXP432P401R.c file)

/* ADC configuration structure */
const ADCMSP432_HWAttrs adcMSP432HWAttrs[MSP_EXP432P401R_ADCCOUNT] = {
    {
        .channel = ADC_INPUT_A0,
        .gpioPort = GPIO_PORT_P5,
        .gpioPin = GPIO_PIN5,
        .gpioMode = GPIO_TERTIARY_MODULE_FUNCTION,
        .refVoltage = REF_A_VREF2_5V,
        .resolution = ADC_14BIT
    },
    {
        .channel = ADC_INPUT_A1,
        .gpioPort = GPIO_PORT_P5,
        .gpioPin = GPIO_PIN4,
        .gpioMode = GPIO_TERTIARY_MODULE_FUNCTION,
        .refVoltage = REF_A_VREF1_45V,
        .resolution = ADC_8BIT
    }
};

0 Ryan Brown1 over 8 years ago in reply to Jan Cumps

TI__Guru**** 217467 points

Thanks for updating the thread with your solution!

Ryan

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MSP432P401R: different values on ADC0 and ADC1