Backup battery for AT91SAM9261
in [Embedded]
|
Prev: RTOS brands
Next: Low cost GPIB-USB controller
From: Ulf Samuelsson on 6 Mar 2006 17:46 > I understand that the processor can boot from the serial flash. So it > can not boot from a NAND flash. Again, I consider this a shortcoming > of the chip that requires yet another small chip to be placed around > the CPU to make it functional. > Only if you actually need to have the NAND Flash. normally people are keeping the kernel and the file system in that small serial flash. Many build Embedded Linux systems with downto 4 MB of Flash or even 2 MB. Won't do too much, but there is significant volume in these applications. You can get 8 MB in the same form factor today and 16/32 MB are in development. Small size NAND flash are dying out, so even if you get much more memory w NAND, that won't help you if you dont use it. -- Best Regards, Ulf Samuelsson ulf(a)a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB
From: rickman on 6 Mar 2006 18:39 Ulf Samuelsson wrote: > > I understand that the processor can boot from the serial flash. So it > > can not boot from a NAND flash. Again, I consider this a shortcoming > > of the chip that requires yet another small chip to be placed around > > the CPU to make it functional. > > > > Only if you actually need to have the NAND Flash. normally people > are keeping the kernel and the file system in that small serial flash. > > Many build Embedded Linux systems with downto 4 MB of Flash or even 2 MB. > Won't do too much, but there is significant volume in these applications. > You can get 8 MB in the same form factor today and 16/32 MB are in > development. > > Small size NAND flash are dying out, so even if you get much more memory w > NAND, > that won't help you if you dont use it. I don't know where you are coming from. I don't have any trouble using fully the NAND flash in a design. Heck, the FPGA on the board alone can use up to a couple of MB of flash. What I am trying to do is to not have to add a NAND flash for the capacity and then also add another flash for code storage. That just seems so wasteful of cost and board space. There are a number of ARM devices that will boot from NAND flash and that will be shown on the next ARM chart I put up on www.gnuarm.com.
From: Ulf Samuelsson on 7 Mar 2006 02:27
rickman wrote: > Ulf Samuelsson wrote: >>> I understand that the processor can boot from the serial flash. So >>> it can not boot from a NAND flash. Again, I consider this a >>> shortcoming of the chip that requires yet another small chip to be >>> placed around the CPU to make it functional. >>> >> >> Only if you actually need to have the NAND Flash. normally people >> are keeping the kernel and the file system in that small serial flash. >> > I don't know where you are coming from. I don't have any trouble > using fully the NAND flash in a design. Heck, the FPGA on the board > alone can use up to a couple of MB of flash. What I am trying to do > is to not have to add a NAND flash for the capacity and then also add > another flash for code storage. That just seems so wasteful of cost > and board space. > > There are a number of ARM devices that will boot from NAND flash and > that will be shown on the next ARM chart I put up on www.gnuarm.com. Yes if I compile the Buildroot enabling everything in the system, the flash disk becomes 3-400 MB. Then again, I see most or all large volume designs (>= 100ku/year) I know about will fit into 4 or 8 MB. There are also several designs where 256 kB Flash is quite enough. They want a low power micro which runs faster than allowed by on chip flash solutions and like the large internal SRAM memory. So is booting from NAND a bad thing? of course not. -- Best Regards, Ulf Samuelsson ulf(a)a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB |