Saeed wrote:
> Hi, I'm trying to build a system using AT91RM9200 208pin (Linux) and I
> would greatly appreciate anyone share his experiance on using just SPI
> Data Flash like AT45DB642 on AT91RM9200 208pin without using other
> kind of memory on Linux
Since the AT45DB642 is obsolete, you want to move to AT45DB642D....
You should limit your SPI speed to about 5 Mbps if you use Ethernet
or Compactflash or other heavy DMA activity.
If you want to run faster then you should make a H/W workaround for Errata
#13.
!DF_CS = !NPCS0 or !GPIO
The boot code will force NPCS0 low enabling the dataflash chip select.
The GPIO signal is used as chip select all other times.
This added gate should allow you to run much much faster on the SPI.
If you insist on using the AT45DB642 (maybe on an old board) ,
then you must take care of the 250 ns
hold time of the AT45DB642 (only 5 ns for the 642D) which is incompatible
with the Linux/U-Boot Drivers. Only found out this problem last week.
--
Best Regards,
Ulf Samuelsson
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
Linear Mode
