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Multiplexing two SPI Master

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wat007

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Is it possible to switch two master SPI lines using Quad 2:1 multiplexer like (74HC257)? I want my two Master devices to access a single SPI slave (Flash). SPI speed is 4MHz. Please see attached schematics.

The reason for this is that, I have an MP3 module (master2) which already has a flash that I want my MCU (master1) to access the data from. I don't have control on SPI lines of MP3 (Master2). Schematics.jpg
 

Hi,

Your multiplexing should work.

MISO doesn't need to be switched.
I'd add a pullup resistor at !CS of flash.

You need an arbitration before switching MUX to prevent data corruption.

Klaus
 

Thanks KlausST, I will post my results soon.
 

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