[ECOS] ADC polling vs. ADC generated interrupt
Peter Huszar
duci750@yahoo.com
Sat Dec 27 21:39:00 GMT 2008
Hi Uwe,
First of all I would like to stress, that I am just starting to find out the capabilities
of the LPC2000, and I am asking questions in the hope of getting a better
understanding.
There are two reasons why I posted the question:
1) If I understand correctly, the burst mode is really a continuous mode,
where conversion is performed continuously. I have a preconception
of using ADC taking a couple of samples in about once a second for
checking some temperature data. From this I would assume that some
tens of thousands of samples will be collected continuously before a read
is made that actually requires the data. Setting the timer to 1/10 sec, turning
the burst mode off, using the hardware start conversion signal, would result
in max 80 reads per second. This would imply to me less time spent
servicing interrupts, less power, less noise etc.. Even if the ADC would be run
on full speed, the above method should not slow it down considerably just
because of the different use of the interrupt. Of course, at full speed, serving
8 interrupt might cost more than 1 interrupt plus polling 8 registers.
2) If this mode is acceptable, maybe a uniform approach could be considered
for the lpc21xx/22xx/24xx driver.
Please correct me if I am wrong in any of my assumptions. I would also welcome
your comments since you have practical experience with the ADC.
Please let me know if this idea is not worth pursuing. I would not like to waste
precious time on some futile attempt as a result of my lack of understanding
of the intricate hardware details.
Regards,
Peter
Original Message ----
From: Uwe Kindler <uwe_kindler@web.de>
To: Peter Last NameHuszar <duci750@yahoo.com>
Cc: ecos-discuss@sourceware.org
Sent: Saturday, December 27, 2008 5:10:00 PM
Subject: Re: [ECOS] ADC polling vs. ADC generated interrupt
Hi Peter,
why would your idea of using timer1 without interrupts and let the ADC generate interrupts after each conversion be more efficient? Please give me some more hints why this method would be more efficient.
Thank you, Uwe
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