SPI 8451 with labview , CS issues

[Cobmetal]

HI , im using NI 8451 I2C,SPI module .

used NI few examples and wrote a simple code to communicate Master-->Slave .

The problem is that the CS' , isnt toggles when i toggle it , it always on 3.3V.

Im using Labview 2016.

What could be the issue ?

Thank u.

[Brian.D]

The NI-8451 uses an active low chip select by default, and its output high voltage is 3.3 V. Even when running the examples, do you see this behavior? Otherwise, if you want to change the behavior of the NI-8451 so that it uses an active high chip select, refer to the following document: http://digital.ni.com/public.nsf/allkb/4D3F32C0318FEE5D862574B3006A5726?OpenDocument. 

[Cobmetal]

Hi , yes its behave as you said , all the CS ports are 3.3V , but my question is : How i can change the CS to be 'LOW" ? .

im using the "porperty node" "NI-845X SPI configuration to control the ChipSelect , but it doesnt change anything.

I've added only one part of the code .

[Brian.D]

The CS line should be pulled low once the line is selected using the SPI Basic API. After the portion of code you included, you should be able to read/write successfully. 

If you wish to have more control over the CS line, you can use the SPI Scripting API. This includes 2 VIs (CS Low and CS High) which allows for setting the lines low and high. I recommend looking at some of the examples in LabVIEW for this API. In addition, you can refer to the following document (section 3, scenario 1) for more detailed information: http://www.ni.com/white-paper/8359/en/. 

[Cobmetal]

Hi , the interesting thing is that : when i pulling the CS low , and measuring the voltage , i still measure 3.3V , insted of GND .

[Brian.D]

Are you measuring the CS line that you are selecting? In addition, are you able to write and read data using this line? If you are unable to write and read data on this line, and it seems that it always is 'High', then the device may be damaged.

[Cobmetal]

HI ,

Yes im measuring the CS line using using DVM , and i measure always '1' , it seems that im able to write , but not to read .

i've tried two devices.

Maybe you have some simple code , that you can upload , and ill check ?

[Brian.D]

There some write and read examples in LabVIEW (example finder) that you can try out: ensure that you are wiring and configuring your device properly.

[Cobmetal]

Hi , based on the examples , i wrote a code for read and write , using SPI scripting.

i've attached probes to all the 4 signals , and analyzing the signals , the strange thing is that the MISO line , is not on Hi-Z . 

im attaching the screenshots and the VI .

 

[Cobmetal]

Hi ,

tried to use the internal labview examples for reading and writing , and it seems that everything goes well.