Hi !
First, sorry for the errors i may do, but i don't speak English very well 
Then, i need help for a project that uses an arduino yùn and a bluetooth module, connected by SPI to this yùn. As the Spi on this board uses the ICSP pins, i connected all. The wiring works well, i tested it with basic sketches. The problem is that the white usb led meaning that the linux processor has booted never turns on, the usb host , the wifi and the sd card don't seem to work.
I've tried to unplug all from my yùn, and to reboot it, but nothing changes !
What could i do ?
Thank you very much for your help !
While having something connected to the ICSP pins could affect your ability to load a sketch over the network, it should not affect the way that Linux boots. I suspect you have a sketch that is immediately trying to send something to the Linux side as soon as it starts up, and that is interrupting the Linux boot process. The serial port that is between the two processors is also the Linux console. There are a couple places during the boot process where you can type any key to interrupt the boot process. If the sketch happens to send data to the Linux processor during these times, it will prevent Linux from booting.
The simplest way to test this is to load the Bare Minimum example sketch which sends nothing to the Linux side. if the Linux side boots properly (takes over a minute after power on) then this is likely your problem.
Look here for more information: How to improve reboot/reset stability
Thank you for your help !
I put a delay at the beginning of the sketch in order to wait for linux to boot, and it works very well !
Thanks again