ADuC7024 ADC - Misc questions

Hi,


I have a few questions regarding the behaviour of the ADC peripheral on the ADuC7024 that I hope can be commented on:


i) After an ADC conversion has completed (ADCReady = 1) are the contents of bits 0 to 15 in ADCDAT all 0 or other/undefined?


ii) Data sheet Rev C, P44 says that reading ADCDAT clears ADCReady (ADCSTA, Bit 0). Does this also clear the ADC Channel (bit 7) in IRQSIG?


iii) With ADCCON configured for conversion on Timer 1 (bits 2:0 = 001) is it acceptable to read ADCDAT after a previous conversion has been performed (ADCReady = 0) and while a new conversion is in progress (ADCBUSY = 1)? I want to avoid the possibility of reading a value that is neither the result of the previous, or current conversion, such as when the result is being transferred internally to ADCDAT?


iv) What happens if ADCCON is written to/changed, while an ADC conversion is in progress (ADCBusy = 1) - does it affect the conversion in progress?


v) What happens if ADC channel is changed (ADCCP) while an ADC conversion is in progress (ADCBusy = 1) - does it affect the conversion in progress?


Thanks.

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  • 0
    •  Analog Employees 
    on May 1, 2014 3:03 PM

    (iv) Writing to ADCCON when a conversion is under way will cause the current conversion to stop and a new conversion to start.

    (v) Same as (iv)

    I'd like to make a correction to (v)

    I found that writing to ADCCP does in fact not restart the ADC. If I change ADCCP during the conversion phase, the next result I get is from the first channel, and if I change it during the aquisition phase the result I get is from the second channel. Also looking at the ADCBusy pin the timing doesn't change.

    One thing to note in the second case where the result is chagned during the aquisition phase is that the ADC aquires the first channel for some time and then the second channel, so the result will be some convoluted mix of both channels.

    This seems to be the case for ADuC702x parts and ADuC7023 and from talking to people SAR ADCs are normally like this.

    Regards,

    Alex

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  • 0
    •  Analog Employees 
    on May 1, 2014 3:03 PM

    (iv) Writing to ADCCON when a conversion is under way will cause the current conversion to stop and a new conversion to start.

    (v) Same as (iv)

    I'd like to make a correction to (v)

    I found that writing to ADCCP does in fact not restart the ADC. If I change ADCCP during the conversion phase, the next result I get is from the first channel, and if I change it during the aquisition phase the result I get is from the second channel. Also looking at the ADCBusy pin the timing doesn't change.

    One thing to note in the second case where the result is chagned during the aquisition phase is that the ADC aquires the first channel for some time and then the second channel, so the result will be some convoluted mix of both channels.

    This seems to be the case for ADuC702x parts and ADuC7023 and from talking to people SAR ADCs are normally like this.

    Regards,

    Alex

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