View Full Version : Selective Loading and FLASH Memory questions

02-05-2007, 01:59 AM
Hey guys, I am nearing completion of my Retrosys system design, but I want to verify that my concepts will work, and get a little feedback on my PCB layout (which I will post soon)
The main feature of the Retrosys system is that it features internal flash memory that holds all the game programs and data, which is downloaded through PC.
I need to make sure that the boot procedures of the Propeller will do what I am expecting they will.
I plan to have the 32kb external EEPROM connected to pins 28 and 19 as per the suggested diagram.
By default, the system's main menu system will be loaded there, and execute all the menus and browsing and whatnot.
However, when the user wants to run an application, I need the system to copy the appropriate data from the Flash Memory into the appropriate EEPROM memory (I have dedicated video/audio/etc. memory modules), load up the program data and run it, BUT, I need the main system program to maintain some means of control so that when a game is 'quit' it will return to the main system.
The main way I was planning to do this was:
1) load game data from FLASH to EEPROM modules,
2) load game program data to 32kb external EEPROM,
3) reset the Propeller to run the game
then, at the beginning of each game application:
1) re-load the system 'os' or whatnot program into the external 32kb EEPROM
2) when return-to-system is desired, reset propeller

I would have a section of the FLASH memory dedicated to holding the primary operating program and data.
I think this method would work, It also ensures that you will return to the system 'os' is you reset manually, or have power failure.
However, if there were any power losses during transmission of the system os to external ROM, you would have issues, and need to redownload the system os to external EEPROM.

I think this method would work OK for now, but does anyone have any better ideas?

Also, I need some help finding a good Flash memory module. I'm shooting for the 128-256 Mb memory range. The system has 4mb of EEPROM memory for graphics, sound samples, possible 3D data, physics data, etc. I know it may not run applications that advanced, but I'm designing it to be capable.
I am only somewhat well-versed in serial communications. I was attempting to find a Serial flash module to interface with the propeller for data storage purposes, but on both digikey and mouser, I'm finding that pretty much all the serial flash modules aren't ever in stock.
Can anyone suggest a good way to add 128-256 Mb of mass storage to my system, and also, suggest some wiring schemes? The 'serial' flash modules I've found are different than 2-line serial, they have a clock, in, and out lines.

Thanks a bunch,

EDIT: BTW, I have been looking at Atmel's DataFLASH line, you can find more info here: http://www.atmel.com/products/DataFlash/
Can anyone give me any input on how to interface with these guys though? Thanks a bunch, I'm still trying to learn alot :D

Post Edited (Sachiel7) : 2/4/2007 7:08:45 PM GMT