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Re: [ts-7000] Read onboard ADC on ts7370

To: ts <>
Subject: Re: [ts-7000] Read onboard ADC on ts7370
From:
Date: Mon, 15 Nov 2010 18:32:48 -0800
After running the  code found in :
ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7250-linux/samples/ adc_72xx.tar.gz

I have

ts7000:/usr/local/epics/tests/adc/adc# ./adc_7250 
Calibration Values = 
[ 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0  ]
Board has been calibrated by Technologic Systems...
Channel 0: 1.558V
Channel 1: 2.506V
Channel 2: 2.506V
Channel 3: 1.874V
Channel 4: 3.449V

With channel 0 grounded to DIO2 of the 40 pin connector. 
(http://www.embeddedarm.com/about/resource.php?item=409#section5.1)

How come I don't read 0v!!!
Is it common ground for the ADC? It seems to be for the DI (IN_00 ... IN_05).
Is it my calibration? I can't be believe I would be that far off!
Crosstalk? Well, maybe for channel 1 to 4 but not 0 since it is diretly 
grounded.

So what is it?
How come I can't measure 0v?

Also I noted that the ADC range is 0 to 3.3V.
Why not use TTL voltage 0-5v instead? 
Is it because the entire system is powered at 3.3v?

Thank you for your insight,
--
Emmanuel





On 16:45 Mon 15 Nov     ,  wrote:
> 
> Found some code for the 7250 which appears to be compatible...
> ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7200-linux/samples/
> 
> Do I have to read the ts72xx manual for the ts7370 ?!?!?
> I guess so...
> 
> -- 
> Emmanuel
> 
> On 16:03 Mon 15 Nov     ,  wrote:
> > Any sample code?

-- 
Emmanuel


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