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I am looking for a way to redirect 6 pcb traces with a push of a single button.

There is micro controller with a SD card connected and I would like to access the SD from a computer without needing to take the SD card out.

The plan is to use a SD card reader and solder wires to the pads inside and connect that with a 6 way cable plug. I would then need to disconnect the PCB traces going from the micro controller to the SD card so that it wont power up the system with 3.3v from USB.

Is this possible?

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An Octal buffer/line driver with 3-state outputs 74HC244 can do what you want.

enter image description here

Each output buffer quad is controlled by a single enable pin. Use as many as you need (taking care of the data direction for each line of the SD card)

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  • \$\begingroup\$ Hi, I have attached an image with two 74HC244, is this the way you intended to use them? !74HC244 6-way switch \$\endgroup\$ – martin123 Jan 14 '14 at 8:47
  • \$\begingroup\$ @martin123 The !OE pin is active low, you need to apply two states, high and low. You either use a pull down resistor and use the switch to pull up or the opposite. Also the buffers have direction, from A to Y , in your schematic they are all connected in one direction from reader to the card but not all pins of the SD reader are outputs. \$\endgroup\$ – alexan_e Jan 14 '14 at 8:58
  • \$\begingroup\$ Something like this? !6-way Switch \$\endgroup\$ – martin123 Jan 14 '14 at 9:24
  • \$\begingroup\$ @martin123 Yes the direction seems correct, the only part I'm in doubt is if the transition is going to create problems especially with the switch bounce. It would be better if you can replace the button from two lines of the mcu that turn one section off and then turn the other on \$\endgroup\$ – alexan_e Jan 14 '14 at 9:34
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Yes, use an analog switch or multiplexer: Maxim's lineup

You could use 3 dual SPDT or 2 triple SPDT, the details are up to you. This is the way I would go about switching this card. Your control signal will be generated by your microcontroller. It could -- for instance -- connect the card to itself or the computer by bringing a GPIO line high/low.

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