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ADS8860: ADS8860 data retrieval and interpretation

he dajiang
Prodigy 196 points
Part Number: ADS8860

I have two questions regarding to 8860 reading

1. According to data sheet, it is a 16-bit ADC. But nowhere can I find info on how to convert 2 bytes to voltage. The following is how I do conversion:

	adc_8860_val = a_SPI1_3_RxBuf[0] * 256 + a_SPI1_3_RxBuf[1];
	adc_8860_val = adc_8860_val * 3.3f / 65536.0f;
Is it the correct way?

2. I use 3-wire CS mode without busy indicator. From CS high to CS low, I delay 1ms, which is very long. However, according to data sheet, as long as it's longer than max-conversion time, it should be OK. Am I right?

  • 0
    Prodigy 196 points

    One more question:

    If my Ref voltage is 2.5v, AINN connected to GND, AINP input cannot be negative, right?

    If AINP is negative, my ADC reading should be 0, isn't it?

  • +1 in reply to he dajiang
    TI__Guru 60156 points

    Hello he dajiang,

    Thank you for your post.

    The ADS8860 is a unipolar, single-ended input device. This means that the negative input (AINN) should be connected to ground, while the positive input (AINP) can range from 0V to VREF.

    The device output format is straight binary. To convert ADC codes to volts, simply convert the ADC conversion value from binary to decimal, then multiply by the LSB size. 1 LSB = VREF / 2^16.

    Regards,

    Ryan