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mpustovoyt
11-20-2010, 02:44 AM
I am new here I want to use multiply propeller chips. The chips will be very close on board The question is how can I synchronize clock of 2 or more propeller chips?
Can I use single crystal for 2 or more propeller chips? or I can use some external clock for example from master chip use dedicated pin and attach it to slave clock pin (XI, XO)
Thanks, Max

hinv
11-20-2010, 05:25 AM
Hi Max,

I would suggest you read http://forums.parallax.com/showthread.php?t=124343

I think it is right up your alley.

prof_braino
11-20-2010, 03:15 PM
I believe that one propeller can use a single line to generate a signal that can be used as clock for other propellers.

So the first chip has a crystal, and an output from this first chip provides the clock on all the other chips.
The difference is the actual crystal is only connected to the first prop.

Is this what you have in mind?

Sapieha
11-20-2010, 03:37 PM
Hi prof_braino.

As it is possible --- In same time not always recomended.

Think You any situation You will Control if other Propeller is working from other.

IF You use that solution -- IF first one that control Frequency STOP - entire system stops and sometimes that can be very BAD!




I believe that one propeller can use a single line to generate a signal that can be used as clock for other propellers.

So the first chip has a crystal, and an output from this first chip provides the clock on all the other chips.
The difference is the actual crystal is only connected to the first prop.

Is this what you have in mind?

prof_braino
11-20-2010, 05:19 PM
As it is possible --- In same time not always recomended.

IF first one that control Frequency STOP - entire system stops and sometimes that can be very BAD!

Of course. In my case, if the first one stops, I always want the others to stop.

I just wanted to point out that this could be done much simpler that the first example given.

I would not run my pacemaker off the second prop if I planned to stop the first. :smhair:

mpustovoyt
11-20-2010, 07:01 PM
Hi Max,

I would suggest you read http://forums.parallax.com/showthread.php?t=124343

I think it is right up your alley.
Hinv, Thanks a lot, This is almost what I am looking for :)
I really like propeller arhitecture!

mpustovoyt
11-20-2010, 07:06 PM
Prof_braino,
Yes, something like that. The main goal is to have the clock of all propeller chips to be synchronized.
This will allow me to create a simple very fast bus for communication.
PS: I was hopping that new upcoming Propeller 2 will have 16 COGS but it's not a case. I just am running out of COGS :(

mpustovoyt
11-20-2010, 07:16 PM
Sapieha, Do you know any other restrictions such as hardware signal voltage or something like that. For my goal it is OK to have all chips is going down if one went down. I just want a simple way to get more COGs and simple way to share the data between the COGS
Thanks, for raising your point :) Probably it's good idea to have something like separate CPU to watch the overall system health.

mpustovoyt
11-20-2010, 07:19 PM
As it is possible --- In same time not always recomended.

Think You any situation You will Control if other Propeller is working from other.

IF You use that solution -- IF first one that control Frequency STOP - entire system stops and sometimes that can be very BAD![/QUOTE]

Humanoido
11-20-2010, 07:25 PM
To synch up all the props you'll need to use an external crystal oscillator circuit. The output is buffered using gates fed to the props.

prof_braino
11-20-2010, 09:15 PM
Prof_braino,
Yes, something like that. The main goal is to have the clock of all propeller chips to be synchronized.
This will allow me to create a simple very fast bus for communication.
PS: I was hopping that new upcoming Propeller 2 will have 16 COGS but it's not a case. I just am running out of COGS :(

My project is working on a method transparently add more application cogs just by adding more props. First stab will be a 6 prop configuration, one master and five slaves. On the master, 3 cogs are consumed from overhead, and five cogs are consumed by slave communications channels. On the slaves, one cog is consumed for the communications channel. This leaves 5 * 7 = 35 slave cogs available to the user/application. This might not be exactly what you are looking for, but it might be fun to play with.

Sapieha
11-20-2010, 10:15 PM
Hi mpustovoyt.

If You use one pin to drive more that one Propeller from IT.

USE 74HC14 else like IC that distribute that Clock to every Propeller (One Propeller on one 74HC14 Output pin)

DRIVING: all others Propeller's by One of them as Master.
As it is possible --- In same time not always recomended.
"IF You use that solution -- IF first one that control Frequency STOP - entire system stops and sometimes that can be very BAD!"

That situation You can have IF: -->

You build fault tolerant system that one Propeller need test by serial else other type of protocol other one.
BUT You will never have situation that ALL Propellers stops (That situation You can have If You drive Other Propellers By Master one).

In Case You use solution that Humanoido (http://forums.parallax.com/member.php?u=50255) give You it are not possible as every Propeller still will have its own Frequency applied even if one of them STOP functioning.
"To synch up all the props you'll need to use an external crystal oscillator circuit. The output is buffered using gates fed to the props. "




Sapieha, Do you know any other restrictions such as hardware signal voltage or something like that. For my goal it is OK to have all chips is going down if one went down. I just want a simple way to get more COGs and simple way to share the data between the COGS
Thanks, for raising your point :) Probably it's good idea to have something like separate CPU to watch the overall system health.