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Hi again. I wonder if anyone can give some advice on interfacing the Cypress FM25C160B FRAM (SPI) memory chip to a PSOC5. I tried the straight forward approach of specifying an SPI component and connecting the MOSI, MISO, CLOCK, and specified a processor pin for chip select. But no matter what I do, I cannot read anything but zeroes out of the FRAM. Even reading the status register (after setting the WREN bit) returns zero. Is there some reason why my interface will not work? I'd appreciate any comments, especially if you have done this. (By the way the FM25C160B used to be made by a company called Ramtron, but they were bought out by Cypress a few weeks ago. I have used the FM25C160B devices from Ramtron in a number of PIC applications with no problem, but this is the first time I have tried it with a PSOC.
Thanks, Russ
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PSoC 5LP
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This might be of help -
http://www.cypress.com/documentation/application-notes/an89659-interfacing-spi-f-ram-psoc-4
Although for PSOC 4 should adapt easily to 5LP.
Regards, Dana.
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Thanks Dana. I went through the AN and did not find any reason for failure, however one of the techs did find the problem. They had put this 5 volt part into a 3 volt system! I am accessing it remotely, and also did not have the latest schematic so I did not realize what they had done. It turns out that Cypress has a compatible 3 volt part so we have it on order. I seem to recall that some of the GPIO lines are compatible with 5 volt inputs, so it might have worked of they had just supplied 5 volts to the part, but a 3 volt part is a better solution.
Thanks again, Russ
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Yes, you can do level shift with the Vddio quadrant settings, but
constrained to <= Vdda.
http://www.cypress.com/documentation/application-notes/an72382-using-psoc-3-and-psoc-5lp-gpio-pins AN72382 - Using PSoC® 3 and PSoC 5LP GPIO Pins
SIO pins one exception, they are 5 V tolerant.
Regards, Dana.