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Topic: Why Flash and EEPROM memory?? (Read 971 times) previous topic - next topic

louarnold

I noted that many Arduino boards have both EEPROM memory and Flash memory. I know the EEPROM is normally used for the static program while the RAM is used for volatile data. But I don't know what the flash memory is for?

Also the DUE (ATMEL SAM3U)(http://en.wikipedia.org/wiki/Arduino) has no EEPROM at all. Why is that?

AWOL

Flash memory is where the program and bootloader live
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
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smeezekitty

Flash is for the program, ram is for the data and EEPROM is for storing persistent data by the program.
http://en.wikipedia.org/wiki/Harvard_architecture
Avoid throwing electronics out as you or someone else might need them for parts or use.
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Graynomad

Quote
has no EEPROM at all. Why is that?

For some reason most ARM processors don't have EEPROM, why that is I don't know.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

AWOL

Because ARM processors are not considered microcontrollers.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Graynomad

Maybe they should rethink although I guess ARM may not be interested in what the chip manufactures do with their processor core, they are in the "processor core" business.

But a simple chip like an LPC1114 is definitely a controller, I wonder why the chip makers don't include EEPROM, after all just about all "ARMs" have peripherals and IO, that makes them controllers.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

smeezekitty

#6
Jan 08, 2012, 12:29 am Last Edit: Jan 08, 2012, 12:33 am by smeezekitty Reason: 1
They are going to a new processor core?
I think this is a poor idea.
There is going to be compatibility issues, major changes including a different compiler and no eeprom can be a big deal.
Also there is no significant benefit over an atmega 2560.
From the Wikipedia page:
Quote

Code: [Select]

Arduino        Processor        Flash       EEPROM    SRAM  dig IO pins        PWM       ADC
Due            ATMEL SAM3U   256     0      50K         54          16 16
Mega2560 ATmega2560   256     4K     8K         54           14       16


The only differences I see are higher clock speed (unnecessary in most cases), no eeprom and alot more SRAM which does not make too much difference once you have 8K or more.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

James C4S


They are going to a new processor core?

I believe this is called "extending the product line."


I think this is a poor idea.

You are welcome to think that.  However, it seems very unlikely the current Arduino lines would be discontinued.  The team is expanding the capabilities.  How is that a "poor idea"?  Unless you want to suggest the team sitting around waiting for others to have better idea in this area.  (That way they emulate large corporations and not open source projects.  If that's what you want, then I agree on "poor idea.")


There is going to be compatibility issues, major changes including a different compiler and no eeprom can be a big deal.

Very few projects make use of EEPROM.  As for the others, if someone (not you) would stop complaining about the changes made with the 1.0 release long enough think about why, they might see the changes lend themselves to a new processor core.


Also there is no significant benefit over an atmega 2560

4 times the RAM, significantly faster core speed, and a 32-bit instruction set.  Yeah, I don't see anything better there.  Well except for everything.


The only differences I see are higher clock speed (unnecessary in most cases), no eeprom and alot more SRAM which does not make too much difference once you have 8K or more.

So you went from "no significant benefit" to " alot more SRAM".  Well, maybe that's the significant benefit?

For people saying the "Arduino isn't enough", the Due comes in.  For those who believe it is, boards like the Uno will continue to exist.  If nothing new was released, there'd be a large number of "why doesn't the Arduino team do something ARM??!?!?" threads.

Regardless, nobody is every happy with any direction the Arduino team takes.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

smeezekitty

#8
Jan 08, 2012, 04:15 am Last Edit: Jan 08, 2012, 04:21 am by smeezekitty Reason: 1
Well I thought they were going to completely replace the AVR line with the ARM core.
If they are not going to, that I don't see any significant problem although I would not be likely to buy it.
The limitation is probably still going to be flash capacity. Even though 256K is alot, 512K could come in handy when storing very large data types such as audio and images. I know that you can use and SD card or external chip but sometimes internal memory is more practical.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

James C4S


Well I thought they were going to completely replace the AVR line with the ARM core.
If they are not going to, that I don't see any significant problem although I would not be likely to buy it.

What gave you this ridiculous idea?
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

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