8051 does not oscillate

C

ClueLess

Guest
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess
































--
Posted via a free Usenet account from http://www.teranews.com
 
On Sat, 29 Mar 2008 11:26:50 +0530, ClueLess wrote:

Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have put
the whole thing on a breadboard a hundred times and it has worked every
time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does not
work - the crystal fails to oscillate. I have in fact taken the same
components that form the crystal circuit after successful test to the
PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that works
without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should look
for?

Thanks for your time and attention

ClueLess
Click to expand...
Did you autoroute, or hand route without paying attention to stray
impedances?

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
 
On Mar 29, 1:56 am, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051  experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess
Click to expand...
If your wiring and uC oscillator configuration correct then my guess
is that either you've installed a damaged part, or perhaps the
breadboard layout had extra capacitance that your PCB does not have,
and that your oscillator needs to start up.
 
On Mar 29, 10:56 am, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess

--
Posted via a free Usenet account fromhttp://www.teranews.com
Click to expand...
the best way to debug a circuit, be it analog or digital, is to
identify few important nodes and verfiy their voltage values (both
calculated and observed values must be equal). but digital circuits
are easier to follow coz voltage value is either 0 or somewhere near
5V. so whenever there is a mismatch, try get the required voltage at
the node by tracing the problem from its output........... so u have
solved it.............
 
On Mar 29, 10:56 am, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess

--
Posted via a free Usenet account fromhttp://www.teranews.com
Click to expand...
a mere multimeter will suffice to debug the problem..........
 
ClueLess wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess
You need to add capacitance.!
Click to expand...



http://webpages.charter.net/jamie_5"
 
ClueLess wrote:

Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?
Click to expand...
What value caps are you using around the crystal ?

Graham
 
On 3ÔÂ29ČŐ, ĎÂÎç1Ęą56ˇÖ, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess

--
Posted via a free Usenet account fromhttp://www.teranews.com
Click to expand...


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ClueLess wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention
Click to expand...
As others have pointed out it could be your layout. Best is to post the
layout and if you can, also the schematic.

Do you have a full ground plane on that board?

--
Regards, Joerg

http://www.analogconsultants.com/
 
On 3ÔÂ29ČŐ, ĎÂÎç1Ęą56ˇÖ, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051 experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess

--
Posted via a free Usenet account fromhttp://www.teranews.com
Click to expand...


Do you want access to China's massive pool of electronic
manufacturers... but lack the time to contact suppliers, negotiate
contracts, arrange shipping or monitor product quality? Don't worry -
Let seriouswholesale deal with all that for you.

*Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD /
Audio, and Computer Accessories now by visiting the online wholesale
catalog at seriouswholesale. com You'll have peace of mind thanks to
the seriouswholesale Quality Control, 12-month Warranty on all
products, and easy secure payment by credit card through Paypal.

Selling on eBay or your own online store? Send products direct from
our warehouse to your customers using our unique drop-shipping
service. You can profit by selling hundreds of different products,
without holding any of your own inventory! Any questions you have will
be answered by the seriouswholesale English-speaking customer support
team... Their aim is to make your China electronics importing business
easier to run than ever before.

Welcome to http://www.seriouswholesale.com.

seriouswholesale - Buy from the source, profit without the hassle.

- 12 Months Warranty - No minimum order restrictions - Drop-shipping
with no additional fee - Pay by safely by PayPal seriouswholesale
Wholesale Co., Ltd.: Chinas original and best online electronics
wholesaler & drop-shipper: seriouswholesale. com
 
On Mar 29, 1:56 pm, ClueLess <cluel...@wilderness.org.invalid> wrote:
Hi 8051  experts there

I have made a circuit for remote switching of or on a motor using
89C2051 and the program has checked out in the emulator. Also I have
put the whole thing on a breadboard a hundred times and it has worked
every time as expected without any flaw.

But when I made PCB, soldered all the parts and power it on it does
not work - the crystal fails to oscillate. I have in fact taken the
same components that form the crystal circuit after successful test to
the PCB it still fails.

I have checked the PCB for any errors and also discontinuity for any
breaks - I could find none.

And the crystal is just a slow one, 32.768 kHz clock crystal, that
works without a hitch on the breadboard.

This is just baffling me. Can any of you suggest what else I should
look for?

Thanks for your time and attention

ClueLess

--
Posted via a free Usenet account fromhttp://www.teranews.com
Click to expand...
Try with a higher freq xtal say 6MHz and see it oscillates. If it
does, then you need to add capacitance.

Allen
 
On Sat, 29 Mar 2008 16:48:17 +0000, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

What value caps are you using around the crystal ?
Click to expand...
It is really gratifying to see the number of responses to my query -
the suggestions have really given me a number of leads to test
further.

32.786 crystal, according to literature, needs 11 pf capacitors but I
found this did not work and I had to use either 22 or 33 pf capacitors
to get it work on the breadboard.

I removed the crystal and capacitors from the pcb and connected pins
X1 and X2 of 8051 direct to the breadboard - it works.

On the breadboard everything is widely spaced but on the pcb they are
very close. So it could be a layout problem. I have redesigned the pcb
isolating the crystal circuit from the other parts, added more space
between pads and also added a ground plane under the crystal parts. I
will get the board made and come back after trying it.

And thanks again to all of you for your time and attention

Thanks for your time and attention

ClueLess
































--
Posted via a free Usenet account from http://www.teranews.com
 
On Tue, 01 Apr 2008 08:36:02 +0530, ClueLess wrote:
On Sat, 29 Mar 2008 16:48:17 +0000, Eeyore

What value caps are you using around the crystal ?

It is really gratifying to see the number of responses to my query -
the suggestions have really given me a number of leads to test
further.

32.786 crystal, according to literature, needs 11 pf capacitors but I
found this did not work and I had to use either 22 or 33 pf capacitors
to get it work on the breadboard.

I removed the crystal and capacitors from the pcb and connected pins
X1 and X2 of 8051 direct to the breadboard - it works.

On the breadboard everything is widely spaced but on the pcb they are
very close. So it could be a layout problem. I have redesigned the pcb
isolating the crystal circuit from the other parts, added more space
between pads and also added a ground plane under the crystal parts. I
will get the board made and come back after trying it.

And thanks again to all of you for your time and attention

Thanks for your time and attention
Click to expand...
I hate to nag, but you _did_ include the caps in your layout, didn't
you? If you've got, say, 2x 22 pf and it still doesn't start, you
might try changing the ratio of capacitances (as long as the series
connection still comes out at 11 pf) to diddle with the drive and
feedback.

Good Luck!
Rich
 
On Tue, 01 Apr 2008 22:51:37 GMT, Rich Grise <rich@example.net> wrote:

I hate to nag, but you _did_ include the caps in your layout, didn't
you? If you've got, say, 2x 22 pf and it still doesn't start, you
might try changing the ratio of capacitances (as long as the series
connection still comes out at 11 pf) to diddle with the drive and
feedback.
Click to expand...
Hi Rich

That was the first thing I did, put two 22s in series to get 11 pf and
try. All data on 32.786 kHz crystals said 11pf but the dozen crystals
I had insisted on either 22 or 33 pf

I feel that it is the layout, I am just waiting for the new board,
expected Friday when I will stuff it and see where it goes.

Thanks for your time

Thanks for your time and attention

ClueLess
































--
Posted via a free Usenet account from http://www.teranews.com
 
On Thu, 03 Apr 2008 06:24:25 +0530, ClueLess wrote:

On Tue, 01 Apr 2008 22:51:37 GMT, Rich Grise <rich@example.net> wrote:

I hate to nag, but you _did_ include the caps in your layout, didn't
you? If you've got, say, 2x 22 pf and it still doesn't start, you might
try changing the ratio of capacitances (as long as the series connection
still comes out at 11 pf) to diddle with the drive and feedback.

Hi Rich

That was the first thing I did, put two 22s in series to get 11 pf and
try. All data on 32.786 kHz crystals said 11pf but the dozen crystals I
had insisted on either 22 or 33 pf

I feel that it is the layout, I am just waiting for the new board,
expected Friday when I will stuff it and see where it goes.

Thanks for your time

Thanks for your time and attention

ClueLess
Click to expand...
Are you putting 11pF on _each side_ of the crystal? If so, you're using
half of what you should.

The normal circuit, with a 22pF cap to ground, a crystal, and another
22pF cap to ground, has an _effective_ capacitance of 11pF. If this
makes no sense to you, say so and someone will explain.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
 
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