2008-01-10 16:21:00     SPI CS is not a "1"

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2008-01-10 16:21:00     SPI CS is not a "1"

Alex Stewart (UNITED STATES)

Message: 49458    Hi,

So Ive been trying to get the SPI worked out for a few weeks now. And I think I've finally made it through understanding the framework. I have one problem however. With an o-scope connected up, I can see my CLK and MOSI send my data correctly and my CS line does "frame" my data, but it idles at 1.1V  not ~2.5V like CLK and MOSI......


I thought this may be because of a missing pullup, but even with a 1K pull up on the CS line I cant get it to idle at >~1V.... My device is active low, but it still thinks it is selected even when CS  is "idle"....


Any ideas?


Im using the SPI framework, Slave Select #5 on a BF537-STAMP board....


And its not the ADC im connected to, because the CS acts the same with or without the ADC connected....


Thanks for the Help!!!!




2008-01-14 21:43:02     Re: SPI CS is not a "1"

Bryan Wu (CHINA)

Message: 49570    Hi Alex,


Did you modified any source code to do this test?

CS can be controlled by software driver or user space application.

Maybe a bug I fixed several days ago can be a reference for you.



-Bryan Wu