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ADC acquisition speed

Posted: 11 May 2009, 12:49 PM
by pjc30943
Has anyone reduced the ADC sampling time on a native mode 1280 or 1281? 220us is too slow for this app by about a factor four.

Just curious what side-effects or issues you've come across when manually changing the registers per the ATmega datasheet (from the default) to get a shorter integration time.

EDIT: I might consider an external ADC for higher speeds, but the board is already running a few SPI DACs at high rates, so that resource is tied up much of the time.

Re: ADC acquisition speed

Posted: 12 May 2009, 7:12 AM
by dkinzer
pjc30943 wrote:Has anyone reduced the ADC sampling time on a native mode 1280 or 1281?
You'll want to check the datasheet to confirm but I believe that the GetADC() functions uses the smallest possible prescaler (thus yielding the fastest ADC clock allowable) given the processor speed. You may be able to configure it for a faster conversion time if a lower resolution is acceptable.