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A.C. fishing
02-14-2007, 08:01 AM
Hello.
Would the Propellor detect Flash Memory as EEPROM, and boot up using it?
thanks,
ACfishing

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Somebody said...
-Never Underestimate the power of human stupidity.



Paul Baker
02-14-2007, 08:18 AM
What do you mean by flash memory, an SD card or something? The boot memory must follow the I2C protocol, there are no flash cards which support this protocol.

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Paul Baker (mailto:pbaker@parallax.com)
Propeller Applications Engineer
[/url][url=http://www.parallax.com] (http://www.parallax.com)
Parallax, Inc. (http://www.parallax.com)

Mike Green
02-14-2007, 08:35 AM
The Propeller will only boot up from standard I2C EEPROM at least 32K x 8 in size (or it will boot up from a connected PC via the Propeller Tool). Anything beyond 32K is ignored. It is possible to have the EEPROM contain only a program that loads a program from an SD card or some other SPI flash memory, then starts to execute that program as if it were booted from the SD card or SPI flash memory.

James Long
02-14-2007, 10:28 AM
Mike,

Since this has came up. I understand how the propeller would load it's information into ram, but how would it be initiated?



I'm a little confused how this would be accomplished.

Keep it as simple as you can.....I'm still a newbie with the prop.

James L

Mike Green
02-14-2007, 10:42 AM
James,
I'm not sure what you're asking. Are you asking about the built-in bootstrap loader in the Propeller's ROM or are you asking about what I suggested, that there could be a program loaded into the Propeller's EEPROM that would load something else from an SD card or SPI flash memory?

James Long
02-14-2007, 10:54 AM
Mike,

I'm sorry......again I didn't state my question clearly. (I'm getting a really bad habit of this.)

If there were a small program in the eeprom to be a "SD card program reader" that recalled a program from an SD card or similar, how would the program be initiated after being loaded into memory.

James L

Mike Green
02-14-2007, 11:49 AM
James,
It would probably be provided as a source file with a string constant near the beginning that would give the name of the SD card file to be loaded. This would be compiled and downloaded to the Propeller's EEPROM. When the Propeller was reset, it would (as usual) load the program in EEPROM to RAM and execute it. This program would load the file with the fixed name off the SD card and start the Spin interpreter on it. That's all.

Chip posted a small assembly program fragment that can be used to start a Spin interpreter on a program loaded into memory beginning at location zero. The Propeller OS uses this for loading from 32K pages in EEPROM. I already have the same kind of thing mostly working for SD cards. I'll post it when it's working well enough.
Mike

James Long
02-14-2007, 12:25 PM
Mike,

That was the tid bit of info I was looking for.

I had not seen the assembly program that can be used to start a Spin interpreter on a program in memory.

But thanks......you hit the nail on the head. That is exactly what I need to revise my current system to do. (I will of course have to learn how to use Chip's assembly program to initiate it.....I haven't started with assembly yet.....just trying to get all my ideas working first.)

Thanks Mike......you are getting up to a case of beer (or whatever you drink). The abyss of knowledge.

James L