Hi all,
Just thought I'd say what I've been working on currently - had a slow fortnight w/o much time to spare for it but... I am writing a 2ndstage boot monitor for the E2 with the aim to drop it into the first block (or two ;) of NAND flash via David's pblq program. I currently haven't touched the flash at all, and am using JTAG to download it to RAM - that actually works very nicely, about 3K/s too..
Anyway, it provides a basic shell on the serial port with peek/poke/dump/go style commands. It'll also support YMODEM transfers (when I get them working) to/from DRAM and from NAND - so it'll provide an easy means to prototype bigger programs on top of itself, with quick downloads to DRAM.
I've found the NAND support to be interesting. It's my intention to have it be able to scan internal NAND (and SmartMedia) for headers of code to load/jump to, much as PBL does. The raw NAND contains some strange stuff; there is some sort of FTL in force here. At this point I got a bit exasperated trying to work out exactly what ECC/badblock-remapping scheme they've used in the NAND flash; however I've found the PBL high-level "read offset N" routines (e.g. 0x4d18), and can call them (in ROM) from my own code (in RAM) with success.... These routines seem to perform ECC/FTL-style remapping. I haven't found out how to get them to read SmartMedia though... (Incidentally 0xa0002007 bit 0x02 is an active high 'smartmedia inserted' flag, 0xa0002005 bit 0x01 being the NAND CS for the card.) Thinking about it it would make sense for the ECC/remapping stuff of the internal NAND to be the same as the SmartMedia standard, no point duplicating code for a different system for internal flash...
Anyway; anyone have any comments/input/help with regard to the PBL routines to access SMC or internal flash? I haven't looked for/found the writeBlock routines yet, but they'll be next on the list. Ideally this loader (it's about 8K now since I'm lazy and most is in C) would sit at the (logical ;) ) start of NAND, be brought up by PBL and then boot from either SMC if inserted or else search internal NAND for another image. Would be a cool development cycle to just blast stuff onto SMC card and plug it in rather than waiting for it to download over serial.
Hope to get something ready over the weeken that ppl can play with if anyone's interested.
-Matt
On Wed, 2005-04-13 at 15:28 +0100, Matt Evans wrote: [...]
Just thought I'd say what I've been working on currently - had a slow fortnight w/o much time to spare for it but...
Hah. I've just bought a house. Suddenly I don't seem to have any time any more...
[...]
I've found the NAND support to be interesting. It's my intention to have it be able to scan internal NAND (and SmartMedia) for headers of code to load/jump to, much as PBL does. The raw NAND contains some strange stuff; there is some sort of FTL in force here.
Oo. I didn't know that; I thought PBL was giving me the raw data directly... hmm. This makes a big difference for the stuff I'm doing; now I know that I can call PBL routines and get *reliable* data off the flash. (It also explains why the PBL flash access routines are so complex!)
[...]
Would be a cool development cycle to just blast stuff onto SMC card and plug it in rather than waiting for it to download over serial.
I'm not entirely sure that my E2 *has* an SMC socket. There's certainly no metal socket soldered to the motherboard; someone suggested that it might be possible to insert a card and have it make contact with the metal tabs on the motherboard without needing a socket, but I'm not convinced of this. I'm still trying to scrounge one up to find it.
How complex would a minimal USB stack be? Could we load data off a USB storage device?
Hi David,
Urgh, housebuying... my favourite reason for procrastination. ;)
On 13 Apr 2005, at 18:10, David Given wrote:
I'm not entirely sure that my E2 *has* an SMC socket. There's certainly no metal socket soldered to the motherboard; someone suggested that it might be possible to insert a card and have it make contact with the metal tabs on the motherboard without needing a socket, but I'm not convinced of this. I'm still trying to scrounge one up to find it.
Sounds interesting - may almost certainly be pads for one if it's not fitted. Unless they respan the board and removed it. SMC is a bit nasty though, I can see why you'd prefer USB storage devices!
How complex would a minimal USB stack be? Could we load data off a USB storage device?
I've been wondering this; I have no experience with USB whatsoever though. It could be that porting something like Redboot might be a better idea than what I'm working on ;-) But Redboot and IIRC U-Boot have USB support. Of course if it's easily separable both are GPL so we could reuse their USB stuff! It's likely not to be too compact though.
-Matt
-
David Given -
jan bartnik -
Matt Evans