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Topic: SD SPI MISO sharing issue (Read 127 times) previous topic - next topic


I have been able to get my SD card working just fine with an Arduino Uno. I also have a 165 shift register which works just fine. When I use both at the same time, the SD card is no longer recognizable.

I have  tried numerous things, but just cannot get this solved. If I remove the 165 shift register MISO connection,  and nothing else, then the SD card works just fine.

Has anyone run into this problem before?  Any help would be greatly appreciated.


I buffer MISO coming from SD cards for just that reason. Use 1 gate of a 74HC125, brings it up to 5V level as well. Control OE of the gate with the SD's chip select pin.
The 74HC165 does not have an OE/, be sure to use a 74HC125 gate there also like a chip select line.
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Thanks for that! 

Too bad I wasted 3 hours trying everything I could think of and find online to solve it before asking the question.  I did learn a few things anyhow...


Looks like the 74HC589 has an active-low Output Enable.
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Thanks as well. Good to know.

I've tried it using straight buttons to pins (with a resistor pull up and a cap to debounce).  Works fine, but now the memory issues are apparent. I have to remove most of the non MP3 code to get the menus and MP3 to work.  The MP3 seems to be a serious memory hog.

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