[ECOS] ADC polling vs. ADC generated interrupt

Peter Huszar duci750@yahoo.com
Sat Dec 27 16:10:00 GMT 2008

Hi Uwe,

I have a general question, for which I hope to get some pointers.

I am looking at the LPC21xx/22xx versions with no "01" suffix.
These controllers do not have ADC channel specific registers,
or their own ADINTEN registers, so after converting each selected 
channel, an interrupt will be generated. When reading the general 
purpose data registers, one can find out which channel was converted.

According to UM10114 manual, it is possible to set the start of conversion
to different sources. Of the six hardware sources, two are dependent on pin
(MAT0.2/P0.16 and MAT0.0/P0.22) the others are timer interrupts that need
not be routed to a pin (MAT0.1, MAT0.3, MAT1.0 and MAT1.1).

In eCOS the ARM ADC uses Timer1 interrupt to read the conversion results.
Would it not be more efficient to use a timer (e.g Timer1) with no interrupts enabled
to initiate a burst conversion through one of these hardware ADC conversion 
starting sources, and let ADC generate the interrupt after each conversion?

Is there any drawback? Am I missing some pertinent information?




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