One EEPROM - Many Props

Humanoido · 2009-08-04 21:05

The idea is to use one eeprom with the same program and load it into many props. Can two or more props access and boot the same program from the same eeprom?

Bill Henning · 2009-08-04 21:17

short answer:

no

long answer:

if all but one of the propellers is held in reset, or has already booted, it might work - but its more trouble than its worth i think.

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P!-Ro · 2009-08-04 21:36

Perhaps you could first turn on the main prop, and then it will turn on the others by turning on a transistor giving them power.

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jazzed · 2009-08-04 21:49

Or daisy chain the reset lines ... which would require a propeller pin and a strong pull-down on each device to be connected to the next device reset.
Added: for this to work BOEn should be held low or tied to VSS. The pull-down should be about 2K Ohms to overcome the internal RESn 5K pull-up.
Of course doing this would only allow a 13 Propeller serial mesh

But you could use the left-over pin for a Cylon lights (or Night Rider) LED bar [noparse]:)[/noparse]

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Post Edited (jazzed) : 8/4/2009 9:59:41 PM GMT

Humanoido · 2009-08-04 22:07

How would you connect one eeprom to many props? Can someone sketch a circuit diagram?

P!-Ro · 2009-08-04 22:23

Here is the schematic for the pe kit:

http://www.apexvalue.com/basic_stamp/Updates/downloads/PEKit_BoxCoverInsert-v1.1.pdf

Just connect all the pin 28s and 29s together.

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PG

RossH · 2009-08-05 06:23

@humanoido,

Another idea is to have only prop load from the eeprom, then have that prop load the other props. If you want to to be able to have all props running the same 32k program, the eeprom would need to be at least 64k - the first 32k holds the loader, which loads the program in the second 32k into the other props. If necessary, it can then overwrites itself with the program and reboot itself as well. This is similar to what I do on Cluso's TriBladeProp - the only real requirement is that one Prop be able to toggle the reset pins of all the other props.

Ross.

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mctrivia · 2009-08-05 13:14

you can tie them in a daisy chain booting 1 after the next but the start up time can get really long if you do this.

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jazzed · 2009-08-05 13:56

RossH has the right idea, but only 32KB would be necessary for initial testing.
Downloading all at once from a serial loader would be possible if all have the same clock base.
I have a bunch of DIP40's and might stack them in a parallel bus architecture later.

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--Steve

Propalyzer: Propeller PC Logic Analyzer
http://forums.parallax.com/showthread.php?p=788230

Microcontrolled · 2009-08-05 16:31

@RossH: How would you accomplish this task?

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RossH · 2009-08-06 01:25

Hi Microcontrolled,

If you can control the reset line of another Prop, you just reset it and then use pins 30 and 31 to download a program to it using a simple serial protocol - exactly the same way it normally loads its initial program from EEPROM the PC. There is Parallax code showing how to do this (in the OBEX I think). This mechanism is good enough if all you need to do is load a program into Hub RAM and execute it.

On the TriBlade I use this basic mechanism to download yet another loader which knows how to load a program into XMM RAM (which you can't do with the basic Parallax loader). Then that program in turn contains yet another loader that knows how to load a small part of itself back from XMM RAM into Hub RAM for execution.

Have a look at the various program loaders in the Catalina TriBladeProp target package - "TriBladePropLoader.spin" is the basic one (which works alone), and "Generic_SIO_Program_Loader_1.spin" and "Generic_SD_Program_Loader_2.spin" are the more complex ones (which work together).

Ross.

Edit - this technique emulates a PC downloading to the Prop, not the Prop loading a program from EEPROM - sorry for any confusion.

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Post Edited (RossH) : 8/6/2009 4:23:07 AM GMT

One EEPROM - Many Props

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