S12 / MagniV MicrocontrollersのトピックRe: Flash file system

Flash file system

burra — Thu, 23 Feb 2006 22:41:23 GMT

Hi,
I'm trying to make a CAN router. I'm going to use the s12xdp512 processor. Have bought the softec sk-s12xdp512-a evo board. I need the routing table to be in the non-volatile memory (512k flash). Because of the of the ageing of flash memory I would like to use some kind of flash file system. Have any body heared of this being used on the s12x processor? Or is it a bit overkill? The routing would also nice if it was a AVL tree. Because of the selfbalancing it need to do many moves in the flash memory. Or is it easier to make the routing table a array and program it to the flash in that way?

Re: Flash file system

Nabla69 — Thu, 23 Feb 2006 23:01:28 GMT

Hi burra,

Depends where you intend to use the S12X. But if you plan to leave it in a room at nearly room temperature, Flash ageing and cycles shouldn't really be a problem as they'll greatly exceed the specifications.

If it's a static routing table, Flash seems fine.

If you plan to modify every so often, EEPROM may be easier to manage.

If you change often, I'd put in Flash and do a regular backup to Flash.

Let's think it this way...

If you do a router with S12X, just as well using the XGate to do the job.

XGate will have better performance with RAM as it potentially runs twice as fast from RAM than Flash (potential = depends on CPU accesses).

Furthermore, looks like a real spot on job for the XGate but it doesn't program Flash, just read.

Cheers,

Alvin.

Re: Flash file system

burra — Mon, 27 Feb 2006 17:56:28 GMT

Hi,
thanks for your comments. Have been thinking a bit now and I'm thinking on using the flash to store the routing parameters and on boot load all to RAM. The routing tables are not changed so often but the router is going on heavy duty machinery so it can be very cold some times -40 deg. celsius.

For adding parameters to the flash I going to use serial console and the main core (not the xgate).

Do this sounf like a good plan?

//burra

Re: Flash file system

Nabla69 — Mon, 27 Feb 2006 18:32:50 GMT

Hi Burra,

Seems all right to me. The S12X is qualified Automotive so you have functionalities guaranteed from -40°C up to +125°C.

In this case you won't have zillions of cycles for Flash but your application doesn't seem to require them anyway, so sounds good to me.

If you go lower in temperature, it won't be guaranteed so I would make sure you have a very good oscillator circuitry (so it always starts) and that you are careful when programing flash (especially if you intend to program at lower than -40°C), implement checksums or things like this.

Anybody else thinks about something ?

Cheers,
Alvin.