fpga4fun.comwhere FPGAs are fun

SD card 1 - FPGA connection

SD cards are easily interfaceable with FPGAs. They come in different sizes (standard, mini and micro) but electrically they all work the same way. Let's focus on micro-SD cards since they are conveniently small and popular nowadays.

Micro-SD cards have 8 pins. First the power connection goes on pins 4 and 6.

Then, you need between three and six connections to FPGA pins depending on the mode of operation you decide to use.

SPI mode

In SPI mode, the DI/DO lines are unidirectional. That means:

The SPI mode is often used in microcontroller systems. With an FPGA, we migh be better served with the...

SD modes

In SD modes, the CMD/DATx lines are bidirectional. That means:

So for example, we need these connections in SD one-bit mode: