Problem on reducing the SPI communication time delay with HSDIO

[Miraclestar]

I am working on implementing SPI commands into LabVIEW to use PXIe6555 (HSDIO) to test a chip. Now the vi I designed could work, but it doesn't meet the time requirement, between each byte of MOSI signal, there should be a less than 2us SCK hold time.  

The problem is that for each byte of MOSI signal, there should be a MISO acknowledgment to determine the next step.

For example, I have a command to do ADC reading. The first MOSI byte command is to check the register whether the data is available. And if it is available it will do the ADC reading command. But the oscilloscope shows the time between these two bytes is around 3ms. That might be the time for HSDIO read the register's status and send it back to LabVIEW on my computer, which makes a judgement and then send the next byte to HSDIO.

I also tried the hardware compare but the delay is still ms. Because even though the hardware still can not do the determination for next step.

Does anyone have any idea to solve this problem? Please help. Thank you!

P.S.

I have attached the prototype vi of 'reset' command with two bytes MOSI. 

I also referred the examples in the following.

SPI Digital Waveform Reference Library

http://www.ni.com/example/31163/en/

 Serial Protocol Communication Reference Design for Digital Waveform Devices

http://www.ni.com/example/31200/en/

[AwakeTheField]

Hi Miraclestar,

I can do my best to look into information to help you with this issue, but you will likely find more expertise on this topic by reposting on this forum thread: 

http://forums.ni.com/t5/Components/SPI-Digital-Waveform-Library/m-p/866346

[Miraclestar]

Thank for your reply Alex.

I have looked through that forum thread before. But there were no similar questions and the NI Engineer who designed the library hadn't replied on that forum thread for years... If there are no other replies I would try NI supports or other ways.

Regards,

Star

[AwakeTheField]

Hi Star,

I wanted to let you know that I have spoken with some engineers here in our Systems group to try to find the expertise on this API. The expertise on this area have transitioned some recently, but I am continuing to work to get some answers for you here.

Do you mind elaborating some on your higher level application? There might be some other ways to achieve the same functionality with some higher supported methods.