There can only be one SD card in town

On the Aries MCV, the MMC pins of the HPS are already used to control the MMC flash. However, we need an SD card. So, we decided to add a µSD card on the SPI1 interface because SD cards can be controlled in SPI. So, I added the µSD card to the SPI1 interface like this:

&spi1 {
	status = "okay";
	clock-frequency = <100000000>;

	mmc-slot@0 {
		reg = <0>;
		compatible = "mmc-spi-slot";
		spi-max-frequency = <50000000>;
		voltage-ranges = <3300 3300>;

Before testing on the MCV, we realize tests on the DE1-SoC. Something to notice, we already built the Linux kernel for the DE1-SoC and it booted correctly without the SD card on the SPI interface.… Read more


With Nathan, we work a lot on the creation of the Linux distribution. On my side, I am working on how to add an sd card on an SPI bus and Nathan is working on the driver for the USB WiFi Dongle.

Device tree

An SD card can not be detected and set automatically like a USB device. We have to tell Linux there is a micro SD host on an SPI bus. We have to put a micro SD host on an SPI bus because the eMMC bus is already taken by the Flash. To tell Linux, there is a micro SD host on the SPI bus, the simplest method is to add it in the device tree blob.… Read more