Oscillator Synchronization.

[lord loh.]

I was thinking of having a few 8085 micro processors generate clock pulses in phase. So will using the a single Xtal for several 8085 work? (Do crystals get loaded? :? )

Can the same feedback network be used to send positive feedback to an array of amplifier to generate wave forums in phase?

Thank you.

 

[Jay.slovak]

Why do you want to use 8085 MCU? Aren't there modern and better MCU's than this (Aka 8051's or PIC), or are you forced to use this MCU?

 

[Optikon]

I was thinking of having a few 8085 micro processors generate clock pulses in phase. So will using the a single Xtal for several 8085 work? (Do crystals get loaded? :? )

Can the same feedback network be used to send positive feedback to an array of amplifier to generate wave forums in phase?

Thank you.

Create one crystal oscillator on board. Buffer that and match the routing to the 8085's clock inputs. You'll be loading the buffer not the crystal (acceptable) thats about the best you can do for dirt cheap. All 8085's will see clock edge at same time (in phase)

more advanced methods involve PLL's and such or more advanced digital parts like modern FPGA's that have built in DLL/PLL for syncr & phasing.

You dont want to send positive feedback to your amplifiers. Without a "net" negative feedback, you have the potential for oscillation and/or saturation.

If you want general waveforms in phase, just generate the waveforms from a clock networks that are in phase.

 

[lord loh.]

Yeah, I have to use 8085. But can the crystal be connected so?

I shall try it out practically in a few days time and shall let everyone know....

But please tell me if the theory says it is possibel or not.

 

[Jay.slovak]

Ofcourse it is possible,
the solution (as posted before) is to have crystal running externaly (use 4060 to make external crystal oscilator), then buffer the clock signal and drive all MCUs in paralel with this clock signal, that' all.

 

[Nigel Goodwin]

I can't comment on the 8085, but on PIC's one oscillator pin is an input, and the other an output (presumably all micros are?) - so you can connect a crystal to one PIC, then connect it's oscillator OUTPUT pin to the oscillator INPUT pin of the next PIC. I'm not sure if you can chain then more than that or not, I'm only going from vague memories of an OLD PIC datasheet.

 

[Jay.slovak]

I can't comment on the 8085, but on PIC's one oscillator pin is an input, and the other an output (presumably all micros are?) - so you can connect a crystal to one PIC, then connect it's oscillator OUTPUT pin to the oscillator INPUT pin of the next PIC. I'm not sure if you can chain then more than that or not, I'm only going from vague memories of an OLD PIC datasheet.

Nigel, on PICs the output is Fosc/4 , therefore other devices will be 4 times slower! (If you use clock-in oscilator mode), maybe XT would work as you suppose?

 

[Nigel Goodwin]

I can't comment on the 8085, but on PIC's one oscillator pin is an input, and the other an output (presumably all micros are?) - so you can connect a crystal to one PIC, then connect it's oscillator OUTPUT pin to the oscillator INPUT pin of the next PIC. I'm not sure if you can chain then more than that or not, I'm only going from vague memories of an OLD PIC datasheet.

Nigel, on PICs the output is Fosc/4 , therefore other devices will be 4 times slower! (If you use clock-in oscilator mode), maybe XT would work as you suppose?

NO! - the output is the crystal frequency, it's what drives the crystal. The Fosc/4 is only internal.

 

[Jay.slovak]

Ok, so you ment LP, XT or HS oscilator mode. It was a little unclear in your original post. 8)

 

[Nigel Goodwin]

Ok, so you ment LP, XT or HS oscilator mode. It was a little unclear in your original post. 8)

Where you thinking of the 16F628?, where you can select a pin as the oscillator output?.

 

[Jay.slovak]

I alway think of PICs... I don't know a lot of other MCUs so I am trying to think what would I do If I had such problem, so yes, 16F628 for example.

 

[Nigel Goodwin]

I alway think of PICs... I don't know a lot of other MCUs so I am trying to think what would I do If I had such problem, so yes, 16F628 for example.

Well the 16F628 isn't a very representative example, as you can set a pin as oscillator output - this is very rare amongst PIC's 8)

 

[Jay.slovak]

I alway think of PICs... I don't know a lot of other MCUs so I am trying to think what would I do If I had such problem, so yes, 16F628 for example.

Well the 16F628 isn't a very representative example, as you can set a pin as oscillator output - this is very rare amongst PIC's 8)

Hm, I think all 14 bit and 16bit F series have it, or am I wrong?

 

[Nigel Goodwin]

I alway think of PICs... I don't know a lot of other MCUs so I am trying to think what would I do If I had such problem, so yes, 16F628 for example.

Well the 16F628 isn't a very representative example, as you can set a pin as oscillator output - this is very rare amongst PIC's 8)

Hm, I think all 14 bit and 16bit F series have it, or am I wrong?

Yes, wrong :lol:

Only some of the very new ones do (mostly post 16F628), basically it's only likely to be there if the PIC has an internal oscillator option.

The old 12C508 might?, I've never looked, but they had an internal oscillator - but 16F84, 16F876 and 16F877 series don't.

 

[Jay.slovak]

OK, I checked their datasheet out and I must say you are right
I don't work with these old PICs so I had no clue (I though only 12bit PICs doesn't have Clock in/out). Anyways Thanks!

 

[mstechca]

I was thinking of having a few 8085 micro processors generate clock pulses in phase. So will using the a single Xtal for several 8085 work? (Do crystals get loaded? :? )

Can the same feedback network be used to send positive feedback to an array of amplifier to generate wave forums in phase?

Thank you.

uhh, why use an 8085? Why can't you just make a square-wave oscillator and have two devices running off the same output? After all, everything tied to one output is in phase with each other.

 

[lord loh.]

Ofcourse it is possible,
the solution (as posted before) is to have crystal running externaly (use 4060 to make external crystal oscilator), then buffer the clock signal and drive all MCUs in paralel with this clock signal, that' all.

My search indicates that 4060 is a ripple counter... Or Did I make a mistake? How can I use a ripple counter to make a Xtal oscillator?

 

[Jay.slovak]

Ofcourse it is possible,
the solution (as posted before) is to have crystal running externaly (use 4060 to make external crystal oscilator), then buffer the clock signal and drive all MCUs in paralel with this clock signal, that' all.

My search indicates that 4060 is a ripple counter... Or Did I make a mistake? How can I use a ripple counter to make a Xtal oscillator?

4060 is a standard "14-Stage Binary Ripple Counter With Oscillator"...
More info:
**broken link removed**