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Using NI-USB-8451 SPI interface to communicate with ADS1298

Francesc Xavier Pastor
Prodigy 90 points
Other Parts Discussed in Thread: ADS1298, ADS8345

Hi!

 

I'm trying to communicate ADS1298 with NI-USB-8451 interface in order to get data using LabView. I'm beginning with a simple program just trying to read one register. I connect Ni-USB-8451 directly to the SPI interface of ADS1298. So, I tie RESET and PWRDOWN to high level, I use internal clock putting CLKSEL pin high and I set up the interface according to the datasheet (CPOL=0 and CPHA=1) using 4MHZ clock rate for SCLK. Also I tied both grounds, PCB & NI-USB-8451.

 

As I managed to make the interface run successfully with ADS8345 (I know this one is not so complicated to run), it makes me think that I've designed the program with Labview properly. Through the oscilloscope I can observe SCLK, CS and the commands which I send running well. The problem comes when I wanna read DOUT pin as I don't receive anything. Well, just '0' level. It seems like I can not communicate both devices each other.

 

I'd be grateful if somebody had the same problem and knows how to solve it.

 

Cheers!

  • 0
    Prodigy 90 points

    I've just solved it.

     

    It's very simple but I hadn't realised. Datasheet says that when you power-up, SDATAC mode is the default mode. And also it says in a note below the table that RREG is ignored in this mode. So, I realised how many problems you can have using simple commands if they are ignored.

     

    I feel a little bit embarrased because it's a stupid thing but sometimes it happens and I'm sure I'll not be the last one. So, check that if you have a problem receiving data.

     

    Cheers!

  • 0
    Prodigy 20 points

    Hi,

    Thanks for ur fast reply, i didn't work on it until today...

    Finally i successed the communication with ADC, because i had another SPI component in the bus, so just need to set good CS at each component and the ADC communnicate well !

    And change data to send in software for my own application

    Thanks again

    Best Regards,

    Olivier

  • 0
    Prodigy 60 points

    Hi Francesc,

    i'm working with ads1298 and ni8451, too. Can you provide me  your labview file that you have managed to make the interface run with ads1298. i´m new with labview, some sample code for spi communication would be great

    Regards,

    Tiago Pereira.