What is the best way to do 3 bits data streaming data using HSDIO 6541

[M_Analog_U]

Hi,

I am trying to capture 2 data bits and 1 clock from a custom interface using HSDIO 6541 [8Mb memory]. Two options are tried but none of them gave needed results.

1. Used clock in the interface as HSDIO strobe in and selected Clock [clock is not present during acquisition initiate. and also happens only in bursts] as External strobe using Win32 data stream API. - This mode is not a all triggering and capture is not occuring.

2.  The second option was to give both data and clock as data lines of HSDIO and use sampling clock as Onboard clock. This option works at the begining, but an error with number of samples that can be fetched is happening. This is dependent on the Onboard clock frequency, but I'm not able to understand the excact relation. Is there an equation for calculating the maximum samples, bits used and sampling frequency.

Thanks

Manu

[ds_1]

Hi Manu,

             I've been playing around with same card quite a bit lately so perhaps I can help, although I don't full understand what you require here.

1. If your clock from interface only occurs in bursts I don't believe it can be used as strobe input to 6541 card.

2. In streaming data you may be gathering a large amount of redundent data between bursts that is filling up the memory. I don't believe there is a calculation based on samples/freq etc as I'd imagine that it is dependent on the operating system etc how fast the memory is streamed and the buffer (i.e. the used portion  8M memory) is cleared.

As I see it, if you take more samples in each "fetch" the time taken to do this gives you more time to get clear the buffer before it fills.

I had done something similar but instead of streaming I used the Multirecord method. I know how many samples are in my data bursts. (you could use your first clock edge to trigger the start of each record as long as you know the expected sample size)

ds1