MSP430FR6989: ADC measurement differs from MSP430FR6988

Hi Cameron,

there is no difference in code, I'm using exact the same binary and yes, I'm using TLV to calibrate.

Here is the code :

#define CAL_ADC_20VREF_FACTOR *((unsigned int *)0x1A2A) ///< REF 2.0-V Reference
#define CAL_ADC_GAIN_FACTOR *((unsigned int *)0x1A16) ///< ADC Gain Factor
#define CAL_ADC_OFFSET *((unsigned int *)0x1A18) ///< ADC Offset

TLV-MSP430FR6988 : 0x01A00h : 06 06 23 cd a8 81 30 20 08 0a 8e a5 f4 2b 1c 00 15 00 f8 fe 11 10 fe 7f 00 00 6a 0a 3d 0c 3d 06 56 07 fb 04 db 05 12 06 8f 81 f4 80 04 81 15 10 79 5e 45 66 80 23 83 86 a0 6a b5 ac 48 12 80 bc

TLV-MSP430FR6989 : 0x01A00h : 06 06 ab 7e a7 81 30 20 08 0a 84 da 0c 2c 3a 00 2a 00 f8 fe 11 10 ff 7f 00 00 03 0a dc 0b 00 06 1d 07 cc 04 af 05 12 06 ba 7f e1 7f 0e 80 15 10 49 62 f9 83 9c 89 a6 69 57 3e b9 e9 30 72 39 93

void batterie_Measure(void)
{
unsigned long ulAdcCorrected;


// Turn on ADC & Reference 2.0V 
hw_analog_AdcOn();

// config ADC12 for Vcc/2-Monitor on A31  
BATT_HW_ADC12CTL3 = BATT_HW_ADC12BATMAP;
BATT_HW_ADC12MCTL0 = BATT_HW_ADC12INCH_31 | BATT_HW_ADC12VRSEL_1;

// Start ADC
BATT_HW_ADC12CTL0 |= BATT_HW_ADC12ENC | BATT_HW_ADC12SC;

// Wait for ADC to finish
while(BATT_HW_ADC12CTL0 & BATT_HW_ADC12BUSY);

// Calibrate ADC-Value

// Correct Ref 2.0V
ulAdcCorrected = (unsigned long)BATT_HW_ADC12MEM0 * (unsigned long)CAL_ADC_20VREF_FACTOR;
ulAdcCorrected = (unsigned long)ulAdcCorrected / 32768L;

// Correct ADC-Gain
ulAdcCorrected = (unsigned long)ulAdcCorrected * (unsigned long)CAL_ADC_GAIN_FACTOR;
ulAdcCorrected = (unsigned long)ulAdcCorrected / 32768L;

// Correct ADC-Offset
ulAdcCorrected = (unsigned long)ulAdcCorrected + (unsigned long)CAL_ADC_OFFSET;

// Save ADC-Value
sHWConfiguration.sBattery.wAdcValue = (WORD)ulAdcCorrected;

// Battery Voltage [mV]
sHWConfiguration.sBattery.wVoltageMv = (WORD)(sHWConfiguration.sBattery.wAdcValue * (4000.0/4095.0));

// ADC & Referenz turn off
hw_analog_AdcOff();
}

On a MSP430FR6988 the ADC measures (ADC12MEM0) about 3321 LSB and on a MSP430FR6989 about 3132 LSB for 3,3V Battery voltage.

Both circuits are powered by the MSP-FET with 3.298V. The 6968 shows nearly teh correct voltage, the 9689 measures about 200mV to low.

Any idea why ?

Regards, Bernd

Bernd,
Is this reproducible over multiple devices?

Are you using a launchpad and/or target board, or a custom board to test?

I'm still looking into this, but will get back to you as soon as possible.