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Reverse word order
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Reverse word order

sodafarl posted on 19 Jan 2012 6:35 AM PST
Top Contributor
128 Forum Posts

Hi

I  have developed a data acquisition circuit using the FX3 USB controller with the GPIF data bus set to 16 bits wide where it receives data from an FPGA. As a means of testing this, the FPGA generates a 16 bit count and sends this to the FX3. I can upload the data to Cypress Control Center but when I look at the data, the word order is reversed. For example if the FPGA is generating an incrementing count from 0x0001, 0x0002, 0x003, 0x004 upwards I should expect to see an incrementing count when I up load the data, however the data I receive comes back as 0x0002, 0x0001, 0x0004, 0x0003 etc. This occurs on hardware I have developed, if I load the same FX3 firmware onto the Cypress FX3 development board which again I have connected to an FPGA running the same code as my development hardware the word order is no longer reversed. Anyone have any ideas about this?
 

Sodfarl

Re: Reverse word order

sodafarl posted on 19 Jan 2012 09:04 AM PST
Top Contributor
128 Forum Posts

Hi,

Okay wish I could remove this post as almost as soom as I posted this message I found that the problem wasn't reverse word order but that the lsb of the data bus was delayed with repsect to the other signals.  Once this timing was sorted out I didn't have a problem with the data.

Sodafarl



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