On 05/12/2010 02:34, Alexandre Souza - Listas wrote:
Thist is
enough to be able to connect to a PC SCSI card, format the
drive and read and write files to it....heheh I can even boot off it !
**I AM SPEECHLESS** :oO
:)
It was helped by already having worked some of it out when writing the
emulation for the RM nimbus hard disk in MESS, which is effectivly
bit-banged SCSI.....
Some suggestions:
- Forget bit-bang SPI code. There is a SPI interface on atmega, it makes
things waayy faster
Yep using the hardware SPI, it's just the SCSI that I have to do manually.
- Forget FAT. Use the SD card as a block device, it
will triple the
speed. It won't be readable in PC but will be with a layer of code less.
- Use the fastest processor you can
Of course...the Mega 1284 is good to 20MHz
- Use the internal RAM as a buffer. It will speed
things a lot, move the
data to sdcard in the idle times
I may try implementing that one of the reasons for picking the m1284 was
that it has 16K of internal SRAM.
- Map the entire SD card as a drive, with no
translation. E.G.: The
sector 321 of the card is the sector 321 of the SCSI "hard disk"
That's how I tried it initially, so I know it works I just wanted the
FAT because it makes things much more convenient :)
I'm sure it will be way faster
CONGRATULATIONS! :D
Cheers.
Phill.
--
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush.