Re: [ts-7000] Problem polling A/D's once per second

[Jeff Cunningham <>]

Were you going to attach your sampling code for us to look at?

-Jeff



Kevin Cozens wrote:
>
> Greetings, all.
>
> Four more days have passed and I'm still no closer to figuring out 
> what is
> wrong with the routines which are reading the A/D converters. I've 
> minimized
> the differences between use of the routines as a test program vs. use 
> in my
> application.
>
> When the test program polls once per second the voltages are stable. 
> When my
> application runs, I get about 1 good reading out of every 5 (the 0.382 
> 0.382
> readings). See sample runs of the test program and my application 
> below. ALl
> readings are printed from inside the routines which read the A/D 
> inputs so I
> don't see it as a case of memory getting inadvertently over written.
>
> With the client hoping I can deliver the product at the end of the 
> month and
> my being stuck on this problem for the last week and having no idea 
> what is
> going wrong here, all I can do now is to cheat.
>
> I'll have to modify my application to read the first two channels 
> about 10
> times per second, throw out any negative readings, readings greater 
> than 3.3V,
> and any readings where the two channels differ by more than 10mV. It 
> isn't
> something I really want to do but it seems I have no other option unles
> someone has any explanation as to what's going on.
>
> $ ./adc_7250 |grep readings
> A/D readings: -0.242V -0.241V 0.185V 0.105V 0.104V
> A/D readings: -0.243V -0.242V 0.185V 0.105V 0.103V
> A/D readings: -0.241V -0.241V 0.185V 0.105V 0.104V
> A/D readings: -0.239V -0.238V 0.186V 0.105V 0.103V
> A/D readings: -0.242V -0.240V 0.185V 0.105V 0.103V
> A/D readings: -0.242V -0.242V 0.185V 0.105V 0.103V
> A/D readings: -0.242V -0.242V 0.185V 0.105V 0.103V
> A/D readings: -0.240V -0.242V 0.185V 0.105V 0.103V
> A/D readings: -0.240V -0.239V 0.186V 0.105V 0.103V
> A/D readings: -0.242V -0.242V 0.185V 0.105V 0.103V
>
> $ ./myapp |grep readings
> A/D readings: 0.382 0.382 0.185 0.105 0.103
> A/D readings: 0.382 0.382 0.186 0.105 0.103
> A/D readings: -0.108 -0.167 0.185 0.105 0.103
> A/D readings: -0.244 -0.244 0.185 0.105 0.103
> A/D readings: -0.244 -0.244 0.185 0.105 0.103
> A/D readings: 0.002 0.130 0.185 0.105 0.103
> A/D readings: 0.383 0.382 0.186 0.105 0.103
> A/D readings: 0.117 -0.028 0.185 0.105 0.099
> A/D readings: -0.243 -0.243 0.185 0.105 0.103
> A/D readings: -0.244 -0.244 0.185 0.105 0.103
> A/D readings: 0.001 0.129 0.185 0.105 0.103
> A/D readings: 0.383 0.382 0.186 0.105 0.103
> A/D readings: 0.116 -0.028 0.185 0.105 0.103
> A/D readings: -0.244 -0.244 0.185 0.105 0.103
> A/D readings: -0.244 -0.244 0.185 0.105 0.103
>
> -- 
> Cheers!
>
> Kevin.
>



 
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