PSN-L Email List Message

Subject: RE: AD7142 ?
From: "James Hannon" jmhannon@.........
Date: Thu, 13 Apr 2006 13:50:15 -0500

I basically agree with your analysis of the delays needed. The functions needed for implementing a PID feedback loop can all be done in one sample time. So if the sample rate is high enough it should work fine. If you can balance a scooter with 8 bit microcontrollers I see no reason why a DSP could not close a loop on a siesmograph with a natural period around 1 second or even 0.1 second.

Jim Hannon

---------- Original Message ----------------------------------
From: Brett Nordgren 
Reply-To: psn-l@..............
Date:  Thu, 13 Apr 2006 14:29:25 -0400

>I second Jack's concern.  I'd pretty much written off the possiblilty of 
>doing DSP feedback at anything but very low frequency.  I'd calculate that 
>an absolute maximum for the DSP delay (assuming 37Hz gain crossover) would 
>be about 13ms.  7ms or a bit more would probably be quite tolerable.  Is 
>there any way to do that?

Jim Hannon

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