Hello, I developped a custom board based on UDOO Neo Full schematics. The only difference, in addition to form factor, is the DDR reference : MT41K256M16HA-125 was replaced by MT41K256M16TW-107, which is faster and compatible with the original one. But, when I try to boot using "UDOObuntu 2.1.1 Minimal (14.04 LTS)" downloaded on Udoo website, system hangs before loading second stage bootloader. Logs : " U-Boot SPL 2015.04-21123-g7271b51 (Jul 22 2016 - 14:15:22) Setting 1024MB RAM calibration data port 1 " My custom board freeze here ! On my udoo board, system continue to boot with : " SPL: u-boot second stage will be loaded from MMC0 U-Boot 2015.04-21123-g7271b51 (Jul 22 2016 - 14:15:22) CPU: Freescale i.MX6SX rev1.2 at 792 MHz .... " Is anyone could help me to identify my problem ? (is it necessary hardware probem ?) What steps are processed to launch the second stage bootloader from the first one ? Many thanks,