I found the problems come from other SPI devices on board, which should be 
disabled but I didn't.

"Ju, Jian" <eejju@polyu.edu.hk> &#1076;&#4294967295;&#4294967295;&#4294967295;&#4294967295;&#994;&#4294967295;&#4294967295;&#4294967295;&#4294967295;:1160991548.300849@nsserver1.polyu.edu.hk...
> Hi all,
>
> I'm trying to run the ADC chip LTC1407a on the spartan 3e starter kit. 
> Both the function and timing simulation is validated and the signal 
> AD_CONV and SPI_SCK is just as wanted when I use an oscilloscope to 
> observed the board signal. In other words, 34 SPI_SCK after 1 clock period 
> of AD_CONV. However, the data output is always 0x3FFF when a 10kHz sine 
> wave is applied on both channel.
>
> Firstly I used a 50M clock and as it can't work properly, I lower the 
> clock using the internal DCM to 10MHz and use the chipscope to get the 
> signals out. I found the signal SPI_MISO, which is the output serial data 
> from the ADC, is always '1'. But the signal on board observed by 
> oscilloscope keeps changing '0'/'1'.
>
> Any suggestions?
>
> Thanks,
> JJ
> 

Hi all,

I'm trying to run the ADC chip LTC1407a on the spartan 3e starter kit. Both 
the function and timing simulation is validated and the signal AD_CONV and 
SPI_SCK is just as wanted when I use an oscilloscope to observed the board 
signal. In other words, 34 SPI_SCK after 1 clock period of AD_CONV. However, 
the data output is always 0x3FFF when a 10kHz sine wave is applied on both 
channel.

Firstly I used a 50M clock and as it can't work properly, I lower the clock 
using the internal DCM to 10MHz and use the chipscope to get the signals 
out. I found the signal SPI_MISO, which is the output serial data from the 
ADC, is always '1'. But the signal on board observed by oscilloscope keeps 
changing '0'/'1'.

Any suggestions?

Thanks,
JJ