Hello everyone ,
I want to design an "AT91SAM9G45" specific board and drive it by linux .
Can you help me :
1-What should I do respectively ?
2-I should use some hardware that drivers are not available in linux kernel . How can I solve it ?
Thanks .

You should examine other designs, and review the parts commonly used for certain functions. Pay attention to pricing, and support from the part manufacturer.

If you don't have linux driver coding skills you need to look very carefully at what parts have drivers, and active interest within the development community. If you need a specific part, make sure you can get source code for existing drivers, even from other OS, and be prepared to pay someone to do your work if you can't do it yourself.

Thank you for replay ,

I think your right . I should be careful and use the hardwares that drivers supported by linux kernel . It's easier than pay someone to make software driver.

But first problem is PCB . Everywhere I go , PCB's are very low quality and Chinese . I thing it's very important for a 400MHz CPU .
Ok , I'm going forward on hardware and after PCB evolution , I'll return .
Wish every thing be OK...

Thanks .

I did my AT91SAM9G45 design on an 8 Layer fairly inexpensive board. I used 4mil cleanance, 5 mil traces, and 8/18 vias under the BGA's otheriwse used more conservative routing. Remember to Tint the vias under your BGA's and use a power and ground plane plus 6 routing layers.

I watched the reference design (AT91SAM9G45EKES) very closely and re-used pins to minimize my first Linux design issues.

LED's used same pins, I/O used same pins, etc. I changed minor things like DDR, NAND, and SPI Flash instead of Dataflash. Watch DDR routing and watch LPDDR clock speeds.

Without too much trouble, you can get a bootstrap, u-boot, and kernel running. Since I was doing the hardware and linux stuff, it took me a bit longer to get it all humming.

Thank you gsinde ,

I'll implement these experience .

Thanks again very much .