This simple board breaks out the pins of a microSD card connector to a 0.1″ pin spacing that is compatible with standard perfboards, solderless breadboards, and 0.1" connectors.
MicroSD memory cards (originally known as TransFlash) provide a compact and inexpensive way to add gigabytes of non-volatile storage to a project. All SD cards support communication over the SPI (Serial Peripheral Interface) bus, making it straightforward to interface one of these cards with an SPI-capable microcontroller.
This carrier board makes it easy to connect to a microSD card by breaking out all of the contacts from a microSD card socket into two rows of 0.1″-spaced pins. The board measures only 0.8″ × 0.7″, and a set of breakaway 0.1″ male header strips (one 1×7 and one 1×4) is included, which can be soldered in to use the board with breadboards, perfboards, or 0.1″ female connectors. (The headers might ship as a single 1×11 piece that can be broken in two).
We also carry a larger microSD card breakout board with a 3.3V regulator and level shifters that can be directly integrated into 5 V systems; it only breaks breaks out the more commonly used SPI bus mode interface pins, and it includes two mounting holes. The pictures below show the two versions side-by-side.
Pin Description
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GND(VSS): Power and logic ground
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VDD: Supply voltage (2.7 V to 3.6 V for standard microSD cards)
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CD: Card detect. When a card is inserted, this pin is floating; when no card is inserted, it is shorted to ground. A pull-up resistor can be used to pull the line high when a card is present.
SPI mode
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DI: Data in (MOSI)
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DO: Data out (MISO)
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SCLK: Clock
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CS: Chip select (active low)
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—: Reserved
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IRQ: Interrupt (active low; SDIO devices only)
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—: Reserved
SD mode
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CMD: Command/response
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DAT0: Data (bit 0)
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CLK: Clock
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DAT3: Data (bit 3)
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DAT1: Data (bit 1)
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IRQ: Interrupt (active low; SDIO devices only)
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DAT2: Data (bit 2)
Warning: Standard microSD cards use 3.3 V logic level signals, so level shifters or voltage dividers are required when connecting one to a 5 V system.
Dimensions (Without a microSD card or the included optional header pins.)
- Size: 0.8″ × 0.7″ × 0.12″. When inserted, a microSD card will extend approximately 35 mil (0.85 mm) past the edge of the board.
- Weight: 1.3 g
