ADC (LTC1407a) on Xilinx Spartan 3E starter kit

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 

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
>