Extern micro SD card on T4

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Rawi

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Hello!
I'm using an extern micro SD on T4. I've tried to find out if i need to use pull-up/pull-down on the CS,MISO,MOSI and SCLK , currently I'm using pullup ( to 3V3) resistor on MISO only. Should i use any other pull-up or pull-down on the other pins?

Here is the schematic Extern_uSD_onT4.PNG
 
Here's a nice guide from PJRC themselves: https://www.pjrc.com/better-spi-bus-design-in-3-steps/

Since the T4 digital pins are 3.3V, you don't need a tristate buffer in the MISO, MOSI and SCLK pins, unless you wanted to use it for another device that's 5V.

I believe your MISO pin should float halfway between 3.3V and GND when not in use, according to the guide.
 
Hi RetroD!
Thx for your tips. I don't need level shifter and the MISO is floating as you recommend!
 
Hi balckketter!

The reason is actually the placement of those pins, I'm a new beginner in this field! I thought it would be easier to don't use the SD pins since it i use SPI to communicate with SD.

Here is the 3D view of the PCB:T4BreakoutBoardFront.PNG
T4BreakoutBoardBack.PNG
 
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