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C0-microSD Design-In Guide

The C0-microSD drops into any host with a microSD slot that conforms to the 4-wire SD protocol or SD-over-SPI.

Typical application circuits​

Typical application circuit of a Signaloid C0-microSD with a microcontrollerTypical application circuit of a Signaloid C0-microSD with a single board computer

Example circuit of the Signaloid C0-microSD acting as a co-processor on a microcontroller-based embedded system (left), or on a single-board computer (right)

Power​

Supply the module with 3.3 V on the microSD VDD pad (3.14 V to 3.5 V; see Electrical characteristics). The module generates its internal rails on-board, so the host only supplies VDD. Measured current draw stays below 8 mA on the published reference workload, well within any standard microSD slot budget.

Signal levels​

The SD interface pads (pins 1 to 8) are LVCMOS 3.3. The SPI configuration port on the test pads (pins 9 to 14) is LVCMOS 1.8: connect external programmers at 1.8 V only. See Specifications → Pinout.

Socket or solder-in​

The module works in a standard microSD socket (hot-swappable), or you can design it into a product using the standard microSD land pattern (see Specifications). For development, an open-top socket such as the one on the SD-Dev carrier exposes the test pads for probing.

Standalone FPGA integration​

When the C0-microSD runs a custom user bitstream without an SD host, six microSD pads and five test pads become configurable I/O. Integration details for that use are in Modes and Custom Bitstream.

Next steps​

  • Pinout, the pin names, signal standards, and debug pads your design connects to.
  • Compatibility, the SD host controllers and platforms already validated with the module.
  • Handling and ESD precautions, the assembly, storage, and handling limits for the module.
  • SD-Dev Carrier Board, a reference carrier for probing and power-cycling the module during bring-up.
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