Thank you for your assistance. The problem was solved by changing another micro SD card. For the previous SD card it crashed every time when plugging in.

Hi, I am using CM3 with internal 4GB flash on CM IO Board V3 and i would like to use an external sd card for data storage through the GPIO pins 22-27. I have add following config to /boot/config.txt. dtoverlay=sdio,poll_once=off Here is the result of "raspi-gpio get" GPIO 22: level=0 fsel=7 alt=3 fu...