extending the distance of an micro SD card reader

Thread Starter

rafi533

Joined Aug 17, 2017
2
Hi,
I have foxeer legened 1 1080p video camera

and I need the micro SD card to be 90 cm away from the camera.

I tried to take 2 SD card sniffers like this: (https://www.4project.co.il/imgs/13/product_1334_19165_0x0.jpg)

and connecting them with 90 cm long #24 wires, and to insert 1 side into the camera microSD card slot, and in ther other side i inserted the microSD card itself - but it is not working (seems like the camera is not recognizing it).

Any ideas? Solutions?

thank you!
 

RichardO

Joined May 4, 2013
2,271
The SD card uses high speed signals. To get these signals over that distance will require buffers.

I don't know if a simple solution exists. Maybe others will.
 

Sensacell

Joined Jun 19, 2012
2,567
At 90 CM, the problem becomes non-trivial, the high speed digital signals get significantly degraded by reflections, losses and lack of solid ground at these frequencies.

It "might" work if you use twisted pair cable, with every signal wire twisted with a ground wire.
You may also need a termination network at the cable ends to suppress reflections.

The next level up would be differential line drivers and receivers, again, a non-trivial design problem.

Almost impossible without a fast oscilloscope and some high speed design chops.
 

Papabravo

Joined Feb 24, 2006
13,528
I take it from the signals on the breakout card, that the card is using the parallel interface as opposed to the SPI interface (which is available on full size cards). Using the SPI Interface would be possible with unidirectional line drivers and receivers. I'm not at all sure about using the parallel interface in this way or how you would turn the data lines around.

Turns out you have to use the SPI interface unless you've signed the NDA. So yeah -- use unidirectional line drivers and receivers with twisted pairs. Make sure the devices have edges that are as square as possible and also make sure that you have a really stiff 3.3V Power Supply
 
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