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USB 8452 Clock Phase does not work

Hello,

 

I am using USB 8452 (driver version 2.1) to write and read to an SPI device. I can configure the SPI clock phase to first edge or second edge. The read data from the driver VI is not correct. I connected scope / logic analyzer and try to understand what is going on. It looks like the USB 8452 is always reading the bits in first edge of the clock even though it is configured to read in the second edge of the clock.

 

How do I set the clock phase of the SPI interface sucessfully? Using the SPI configuration property node does not work. Is this possibily a bug in the USB 8452 driver? 

 

Thanks,

A Senthilnathan

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Can you attached your program as well as screenshots of your logic analyzer/scope. 

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Hello GPIB Guru,

 

Thanks for replying to the question. I am able to get it working at 5MHz and upto 10MHz SCLK. However I could not get it work at higher speeds. The reason being the clock does not swing to the full voltage (3.3V) back and forth. For my application, it is ok to communicate at slower speed. So I will investigate more when high speed is required for me.

 

Thanks,

A Senthilnathan

 

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That is weird. I can look at scope captures, but I would expect the clock to be able to go the full voltage range quickly as it has strong drivers. Do you have a lot of capacitance on the bus?

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