Saturday, September 10, 2011

microSD Arduino adapter

Arduinos are meant to be attached to peripherals.  Here is an adapter from a 5V Arduino to a 3.3V microSD card.  To bridge the gap from circuit board to SD card, a socket is used to connect a microSD breakout board (BOB).  Resistor voltage dividers bridges the gap between the voltage differences for outputs.  A low dropout voltage regulator supplies 3.3V power for the SD card.  Inputs from the SD card are within spec for the Arduino, so they did not have to change.

This adapter is a vertical shield.  It has a socket so the pins are accessible if the attachments are compatible.  It only connects to the AREF to D8 eight position socket, which does not have power, so it requires a jumper from 5V(VCC) to one of the slots on its dual socket, so as to replace the 5V socket with another one.  It also has a 1 port card detect (CD) socket, which can be jumpered to another available pin on the Arduino.

It is modeled to support the SD CardInfo example included in the Arudino IDE.  Chip select (CS) is connected to D8 with a jumper, it can be moved to D9 or D10.  It can be used simultaneously with the Ethernet non-shield.

5V Arduino SD Adapter Schematic


  1. How it is work that MicroSD cards can be read through arduino chip board.

  2. microSD card is FAT formatted, and can be supported by a shield as shown, or commercially obtained. See an example and documentation at SparkFun

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