On Feb 19, 2008, at 7:54 AM, Dave Cramer wrote:
>
> On 19-Feb-08, at 1:37 AM, Kevin Cozens wrote:
>
>> Dave Cramer wrote:
>>> Using the sample program adc_7250. I get the following output on
>> my 7260
>>>
>>> ./adc_7250
>>> Calibration Values =
>>> [ 0xffff 0xffff 0xffff 0xffff 0xffff 0xffff 0xffff 0xffff 0xffff
>>> 0xffff ]
>>> No calibration values found...
>> [snip]
>>> 1) I gather it's not been calibrated, are any of them ?
>>
>> So far, I've only seen three 7250 boards. Only one was calibrated.
>>
>
> Interesting, do you recall if the calibrated one measured properly ?
> And if so how does it measure > 5v ?
I have only seen the one 7260 I have, and it has not been calibrated
either. I'm glad to see at least one was - first I've heard of it.
On the 7260 schematic, you can see a resistor-divider giving
0.0625*Vin to the ADC (1% resistors).
The on-board ADC is a little "funny", and the adc_7250 program has
been nothing but trouble for me.
Try ADCpoll.c, which can be found in sources/busybox-1.00-rc2/
coreutils/ADCpoll.c on the linux CD (or on the ftp site).
This may be available as a busybox command depending on how your
system is configured (it was not set up on the stock busybox shipped
with my board).
-Ilya
>>
>>
>> --
>> Cheers!
>>
>> Kevin.
>>
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