Connect MicroSD Card to Arduino Without Shield

Introduction: Connect MicroSD Card to Arduino Without Shield

About: electronic engineer on the way up. :-)

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Step 1: Knowing the Difference Between MicroSD Card and SD Card

I searched out web and find this very helpful photo showing differences

Step 2: Now Time for Making Connections Msd Pin 1 = X Msd Pin 2= Arduino Pin 8 Msd Pin 3 = Arduino Pin 12 Msd Pin 4 = +3.3 Volts Msd Pin 5 = Arduino Pin 13 Msd Pin 6 = GND Msd Pin 7 = Arduino Pin 11 Msd Pin 8 = X

pins 1 and 8 are not connected

Step 3: Now Upload Example of SD "CardInfo" in Arduino Example. Then Open Serial Monitor . and Check Out



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    6 Discussions


    1 year ago

    It seems to me the step 2 statement is incorrect. I think it should be

    msd pin3 = arduino pin 11

    msd pin7 = arduino pin 12

    otherwise good job

    1 reply

    It is true,

    msd pin3 = arduino pin 11

    msd pin7 = arduino pin 12

    (good job)^2

    You should use a logic level shifter between the Arduino and SD/micro SD. It might work for a while without one, but you could fry your card. A 74125 would be a good choice.

    2 replies

    Thank you . I am beginner so please tell me more about logic level shifter

    The digital pins 10, 11, and 13 on the Arduino are going to output 5V signals to the micro SD card. SD and micro SD cards are designed to work off of 3.3V signals to the pins. A logic level shifter just takes the 5V signal and reduces it to the 3.3V.

    The first picture below is the 74125, called a quad buffer. It has 4 of the level shifters. The "E" pin on each buffer is just the enable, which is enabled when low, so pins 1, 4, and 10 can just be connected to ground, along with pin 7. The digital pins that you used on your Arduino should be connected to one of the "D" pins (data in) on the level shifter, with the "O" pin (data out) for that buffer continuing on to where it needs to go on the SD card. For example, Arduino pin 10 --> buffer pin 2, then buffer pin 3 --> MicroSD pin 2.

    The second picture is the schematic for an Adafruit SD shield, which I followed to make my own SD/Micro SD logger (picture 3). From their example, it looks like Arduino pin 12 (MISO) is ok to send straight to the SD/Micro SD pin 7 (data out), because the data on that pin is going out from the SD card and into the Arduino, so the voltage is already set by the 3.3V line going to the SD. Because of this, you only need 3 of the buffers on the 125, which is why pins 13 and 12 on the 125 are connected to pin 14 (Vcc), to disable them.

    74LS125.jpgData Logger Schematic.bmpSD_DATA_LOGGER_STANDALONE_Final.bmp

    I use that same photo! Good work!