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Simultaneous sampling ADC - FX2LP GPIF interface | Cypress Semiconductor

Simultaneous sampling ADC - FX2LP GPIF interface

Summary: 4 Replies, Latest post by TheThinker on 12 Dec 2013 09:51 PM PST
Verified Answers: 1
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jttull's picture
3 posts

 Dear Sirs

We are trying to implement a GPIF interface for a 8 Channel simultaneous sampling SAR ADC (TI ADS8568)

The plan is to use the ADC in parallel interface mode (allow faster sampling) and stream data to a host PC via a FX2LP CY7C68013A-128.

Although this is my first approach to USB micros, after reading some documentation available on the Cypress website, I was able to start a GPIF designer.

The challenge appeared when trying to implement a single read, I run out of States. 

As it can be seems on the attached image (or ADS8568 datasheet) after a conversion signal the host must toggle the RD line eight times to gather the data from the 8 channel, but only 6 states are available.

Any Ideas?

Thanks in advance

VAVC's picture
Cypress Employee
506 posts


No need to move to different (8)states for reading data from eight channels. Read  the datalines when RD(bar) signal goes high and move to other state when it goes high. Go back to previous state to read data when RD(bar) goes low. 




jttull's picture
3 posts

 Dear Vikas

Thanks for you reply.

But how to loop 8 times (or any other number) on a specific state and then move to idle?

As you can see from the ADC parallel read access timing diagram, the FX2 has to set the CONVST_x pin high, wait for the BUSY pin to go low, and then with the CS(bar) pin low toggle the RD(bar) 8 times reading data after the falling edge of RD(bar). After that move to idle and repeat the action until the user aborts the acquisition.

I have been reading the GPIF manual, but this is not clear for me yet.


Your help is highly appreciated 


prji's picture
Cypress Employee
473 posts



It would be easier i fwe get the timing diagra. Please create a tech support case at On eof our engineers can analyze the timing and help you in the same.



TheThinker's picture
37 posts


The register called GPIF Transaction Count Byte Registers GPIFTCB will help you loop through a cycle a definite number of times.

In case if you have already not referred, the best document to understand GPIF is the AN at the link: .

This will help you understand the GPIF using examples.


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