Forums

Crystal not working

Started by dibosco June 25, 2003
Hi folks,

I've just built up my new target board (first one with a 56Fxxx) and
am having no joy getting the crystal going - which is a bit depressing!

I've got a 56F803, with an ACT crystal and 10M across the crystal,
just as the manual suggests and the EVM has.

The crystal is an HC49/U - datasheet can be found on the link below.

http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html

The voltages on the pins of the crytal sit at around 2.6V and Vcc (3.3V).

I assume a blank device should still get the crystal oscillating? If
not, I guess the problem could well be with the JTAG set up.

With that sketchy amount of info, anyone got any suggestions?

Cheers,

Rob.



Hi Rob,

We had some oscillator startup failures (although not at room temperature) on
our 56F807 products, so we went to an external oscillator. This is described in
the following messages I sent on September 5 and 6 of 2002:
September 5, 2002, about 7:50am:
"RE: [motoroladsp] 56F807 expected life cycle"
September 6, 2002, about 6:53am:
"RE: [motoroladsp] Application Note AN2049 vs. 56800/56800E User's Manuals"

We never had an oscillator startup failure at room temperature, so your problem
may be a bad chip or a bad crystal.

Regards,

Art Johnson
Senior Systems Analyst
PMC Prime Mover Controls Inc.
3600 Gilmore Way
Burnaby, B.C., Canada
V5G 4R8
Phone: 604 433-4644
FAX: 604 433-5570
Email:
http://www.pmc-controls.com
-----Original Message-----
From: dibosco [mailto:]
Sent: Wednesday, June 25, 2003 2:02 PM
To:
Subject: [motoroladsp] Crystal not working Hi folks,

I've just built up my new target board (first one with a 56Fxxx) and
am having no joy getting the crystal going - which is a bit depressing!

I've got a 56F803, with an ACT crystal and 10M across the crystal,
just as the manual suggests and the EVM has.

The crystal is an HC49/U - datasheet can be found on the link below.

http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html

The voltages on the pins of the crytal sit at around 2.6V and Vcc (3.3V).

I assume a blank device should still get the crystal oscillating? If
not, I guess the problem could well be with the JTAG set up.

With that sketchy amount of info, anyone got any suggestions?

Cheers,

Rob.
_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this
message will receive your answer. You need to do a "reply all" if you want your
answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:

To Post:

To Leave:

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3 ">http://docs.yahoo.com/info/terms/



Rob -
 
I do not know exactly how you have connected up the crystal, but we have a FAQ that might be of interest.
 
FAQ-20214
 

Question:

I am experiencing some crystal or resonator start up yield problems. Is their something you can recommend to resolve these issues ?

Answer:

The internal oscillator is designed to interface with a parallel-resonant crystal resonator in the frequency range specified for the external crystal in the data sheet. In the data sheet a recommended crystal oscillator circuit is shown. Follow the crystal supplier’s recommendations when selecting a crystal, because crystal parameters determine the component values required to provide maximum stability and reliable start-up. The crystal and associated components should be mounted as close as possible to the EXTAL and XTAL pins to minimize output distortion and start-up stabilization time. The internal 56F800 oscillator circuitry is designed to have no external load capacitors present. As shown in the data sheet no external load capacitors should be used. If your circuit has external load capacitors these will cause crystal start up problems. Removing these capacitors should resolve your crystal start up issues

If your circuit does not have external load capacitors and you are still experiencing a small yield issue you can also try limiting the ESR of value of the crystal you have chosen. The ESR of the crystal can affect the over all gain of the circuit and hence the start up characteristics. Lowering the ESR provides greater gain. An example would be if your crystal manufacturer specifies a maximum of 70 ohms ESR you could request a screen of the parts supplied to you for a maximum of 60 ESR and test to see if this resolves your start up yield issue. Crystal start up is affected by many different board, manufacturing, and crystal parameters and the values for ESR in this FAQ should not be taken as a maximum or recommended value.

Related Products

DSP56F826
DSP56F827
DSP56F801
DSP56F803
DSP56F805
DSP56F807
-----Original Message-----
From: Art Johnson [mailto:a...@pmc-controls.com]
Sent: Wednesday, June 25, 2003 2:43 PM
To: dibosco; m...@yahoogroups.com
Subject: RE: [motoroladsp] Crystal not working

Hi Rob,

We had some oscillator startup failures (although not at room temperature) on our 56F807 products, so we went to an external oscillator.  This is described in the following messages I sent on September 5 and 6 of 2002:
September 5, 2002, about 7:50am:
  "RE: [motoroladsp] 56F807 expected life cycle"
September 6, 2002, about 6:53am:
  "RE: [motoroladsp] Application Note AN2049 vs. 56800/56800E User's Manuals"

We never had an oscillator startup failure at room temperature, so your problem may be a bad chip or a bad crystal.

Regards,

Art Johnson
Senior Systems Analyst
PMC Prime Mover Controls Inc.
3600 Gilmore Way
Burnaby, B.C., Canada
V5G 4R8
Phone:  604 433-4644
FAX:    604 433-5570
Email:  a...@pmc-controls.com
http://www.pmc-controls.com
-----Original Message-----
From: dibosco [mailto:R...@apostrophe.org.uk]
Sent: Wednesday, June 25, 2003 2:02 PM
To: m...@yahoogroups.com
Subject: [motoroladsp] Crystal not workingHi folks,

I've just built up my new target board (first one with a 56Fxxx) and
am having no joy getting the crystal going - which is a bit depressing!

I've got a 56F803, with an ACT crystal and 10M across the crystal,
just as the manual suggests and the EVM has.

The crystal is an HC49/U - datasheet can be found on the link below.

http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html

The voltages on the pins of the crytal sit at around 2.6V and Vcc  (3.3V).

I assume a blank device should still get the crystal oscillating? If
not, I guess the problem could well be with the JTAG set up.

With that sketchy amount of info, anyone got any suggestions?

Cheers,

Rob.
_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://docs.yahoo.com/info/terms/" target="_blank" rel="nofollow">http://www.dsprelated.com/groups.php3">http://docs.yahoo.com/info/terms/



_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer.  You need to do a "reply all" if you want your answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:  m...@yahoogroups.com

To Post:  m...@yahoogroups.com

To Leave: m...@yahoogroups.com

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3


">Yahoo! Terms of Service.



Hi Rob,

I have had problems with the crystal oscillator starting reliable
also (at room temp). Out of 4 prototype boards I was testing 1 would
start reliably, 1 would start randomly and 2 would not start at all.
I did a lot of testing with various capacitors, resistors and
different crystals with no good luck. I finally went with an
external clock oscillator after reading Art's posts. All prototype
and production boards have been working great since.

Pete

--- In , Hutchings William-p23437
<william.hutchings@m...> wrote:
> Rob -
>
> I do not know exactly how you have connected up the crystal, but we
have a FAQ that might be of interest.
>
> FAQ-20214 > Question:
>
> I am experiencing some crystal or resonator start up yield
problems. Is their something you can recommend to resolve these
issues ?
>
> answer
>
> Answer:
>
> The internal oscillator is designed to interface with a parallel-
resonant crystal resonator in the frequency range specified for the
external crystal in the data sheet. In the data sheet a recommended
crystal oscillator circuit is shown. Follow the crystal
supplier&#8217;s recommendations when selecting a crystal, because
crystal parameters determine the component values required to provide
maximum stability and reliable start-up. The crystal and associated
components should be mounted as close as possible to the EXTAL and
XTAL pins to minimize output distortion and start-up stabilization
time. The internal 56F800 oscillator circuitry is designed to have no
external load capacitors present. As shown in the data sheet no
external load capacitors should be used. If your circuit has external
load capacitors these will cause crystal start up problems. Removing
these capacitors should resolve your crystal start up issues
>
> If your circuit does not have external load capacitors and you are
still experiencing a small yield issue you can also try limiting the
ESR of value of the crystal you have chosen. The ESR of the crystal
can affect the over all gain of the circuit and hence the start up
characteristics. Lowering the ESR provides greater gain. An example
would be if your crystal manufacturer specifies a maximum of 70 ohms
ESR you could request a screen of the parts supplied to you for a
maximum of 60 ESR and test to see if this resolves your start up
yield issue. Crystal start up is affected by many different board,
manufacturing, and crystal parameters and the values for ESR in this
FAQ should not be taken as a maximum or recommended value.
> Related Products
>
> DSP56F826 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F826>
> DSP56F827 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F827>
> DSP56F801 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F801>
> DSP56F803 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F803>
> DSP56F805 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F805>
> DSP56F807 <http://e-
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F807>
>
>
> -----Original Message-----
> From: Art Johnson [mailto:art@p...]
> Sent: Wednesday, June 25, 2003 2:43 PM
> To: dibosco;
> Subject: RE: [motoroladsp] Crystal not working > Hi Rob,
>
> We had some oscillator startup failures (although not at room
temperature) on our 56F807 products, so we went to an external
oscillator. This is described in the following messages I sent on
September 5 and 6 of 2002:
> September 5, 2002, about 7:50am:
> "RE: [motoroladsp] 56F807 expected life cycle"
> September 6, 2002, about 6:53am:
> "RE: [motoroladsp] Application Note AN2049 vs. 56800/56800E
User's Manuals"
>
> We never had an oscillator startup failure at room temperature, so
your problem may be a bad chip or a bad crystal.
>
> Regards,
>
> Art Johnson
> Senior Systems Analyst
> PMC Prime Mover Controls Inc.
> 3600 Gilmore Way
> Burnaby, B.C., Canada
> V5G 4R8
> Phone: 604 433-4644
> FAX: 604 433-5570
> Email: art@p...
> http://www.pmc-controls.com <http://www.pmc-controls.com >
> -----Original Message-----
> From: dibosco [mailto:Robert.Wood@a...]
> Sent: Wednesday, June 25, 2003 2:02 PM
> To:
> Subject: [motoroladsp] Crystal not working > Hi folks,
>
> I've just built up my new target board (first one with a 56Fxxx) and
> am having no joy getting the crystal going - which is a bit
depressing!
>
> I've got a 56F803, with an ACT crystal and 10M across the crystal,
> just as the manual suggests and the EVM has.
>
> The crystal is an HC49/U - datasheet can be found on the link below.
>
> http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html
<http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html>
>
> The voltages on the pins of the crytal sit at around 2.6V and Vcc
(3.3V).
>
> I assume a blank device should still get the crystal oscillating? If
> not, I guess the problem could well be with the JTAG set up.
>
> With that sketchy amount of info, anyone got any suggestions?
>
> Cheers,
>
> Rob. >
> _____________________________________
> Note: If you do a simple "reply" with your email client, only the
author of this message will receive your answer. You need to do
a "reply all" if you want your answer to be distributed to the entire
group.
>
> _____________________________________
> About this discussion group:
>
> To Join:
>
> To Post:
>
> To Leave:
>
> Archives: http://www.yahoogroups.com/group/motoroladsp
<http://www.yahoogroups.com/group/motoroladsp>
>
> More Groups: http://www.dsprelated.com/groups.php3
<http://www.dsprelated.com/groups.php3>
>
>
> ">http://docs.yahoo.com/info/terms/
<http://docs.yahoo.com/info/terms/>
> Yahoo! Groups Sponsor
>
<http://rd.yahoo.com/M%1812.3170658.4537139.1261774/D=egroupweb/S
05771855:HM/A64415/R=0/SIGt6t7kdo/*http://www.netflix.com/Defaul
t?mqso`164784&partid170658>
> <http://us.adserver.yahoo.com/l?
M%1812.3170658.4537139.1261774/D=egroupmail/S=:HM/A64415/rand5
759729>
>
> _____________________________________
> Note: If you do a simple "reply" with your email client, only the
author of this message will receive your answer. You need to do
a "reply all" if you want your answer to be distributed to the entire
group.
>
> _____________________________________
> About this discussion group:
>
> To Join:
>
> To Post:
>
> To Leave:
>
> Archives: http://www.yahoogroups.com/group/motoroladsp
<http://www.yahoogroups.com/group/motoroladsp>
>
> More Groups: http://www.dsprelated.com/groups.php3
<http://www.dsprelated.com/groups.php3>
>
>
> ">http://docs.yahoo.com/info/terms/> .



Please be aware that leg capacitors - most MCU
manufactures suggest 22pf-33pf - can kill crystal.
Motorola does not recommend leg caps for its DSP56F80x
devices.

Charlie W

--- Pete Becher <> wrote:
> Hi Rob,
>
> I have had problems with the crystal oscillator
> starting reliable
> also (at room temp). Out of 4 prototype boards I
> was testing 1 would
> start reliably, 1 would start randomly and 2 would
> not start at all.
> I did a lot of testing with various capacitors,
> resistors and
> different crystals with no good luck. I finally
> went with an
> external clock oscillator after reading Art's posts.
> All prototype
> and production boards have been working great since.
>
> Pete
>
> --- In , Hutchings
> William-p23437
> <william.hutchings@m...> wrote:
> > Rob -
> >
> > I do not know exactly how you have connected up
> the crystal, but we
> have a FAQ that might be of interest.
> >
> > FAQ-20214
> >
> >
> > Question:
> >
> > I am experiencing some crystal or resonator start
> up yield
> problems. Is their something you can recommend to
> resolve these
> issues ?
> >
> > answer
> >
> > Answer:
> >
> > The internal oscillator is designed to interface
> with a parallel-
> resonant crystal resonator in the frequency range
> specified for the
> external crystal in the data sheet. In the data
> sheet a recommended
> crystal oscillator circuit is shown. Follow the
> crystal
> suppliers recommendations when selecting a
> crystal, because
> crystal parameters determine the component values
> required to provide
> maximum stability and reliable start-up. The crystal
> and associated
> components should be mounted as close as possible to
> the EXTAL and
> XTAL pins to minimize output distortion and start-up
> stabilization
> time. The internal 56F800 oscillator circuitry is
> designed to have no
> external load capacitors present. As shown in the
> data sheet no
> external load capacitors should be used. If your
> circuit has external
> load capacitors these will cause crystal start up
> problems. Removing
> these capacitors should resolve your crystal start
> up issues
> >
> > If your circuit does not have external load
> capacitors and you are
> still experiencing a small yield issue you can also
> try limiting the
> ESR of value of the crystal you have chosen. The ESR
> of the crystal
> can affect the over all gain of the circuit and
> hence the start up
> characteristics. Lowering the ESR provides greater
> gain. An example
> would be if your crystal manufacturer specifies a
> maximum of 70 ohms
> ESR you could request a screen of the parts supplied
> to you for a
> maximum of 60 ESR and test to see if this resolves
> your start up
> yield issue. Crystal start up is affected by many
> different board,
> manufacturing, and crystal parameters and the values
> for ESR in this
> FAQ should not be taken as a maximum or recommended
> value.
> >
> >
> >
> > Related Products
> >
> > DSP56F826 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F826>
>
> > DSP56F827 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F827>
>
> > DSP56F801 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F801>
>
> > DSP56F803 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F803>
>
> > DSP56F805 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F805>
>
> > DSP56F807 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F807>
>
> >
> >
> > -----Original Message-----
> > From: Art Johnson [mailto:art@p...]
> > Sent: Wednesday, June 25, 2003 2:43 PM
> > To: dibosco;
> > Subject: RE: [motoroladsp] Crystal not working
> >
> >
> > Hi Rob,
> >
> > We had some oscillator startup failures (although
> not at room
> temperature) on our 56F807 products, so we went to
> an external
> oscillator. This is described in the following
> messages I sent on
> September 5 and 6 of 2002:
> > September 5, 2002, about 7:50am:
> > "RE: [motoroladsp] 56F807 expected life cycle"
> > September 6, 2002, about 6:53am:
> > "RE: [motoroladsp] Application Note AN2049 vs.
> 56800/56800E
> User's Manuals"
> >
> > We never had an oscillator startup failure at room
> temperature, so
> your problem may be a bad chip or a bad crystal.
> >
> > Regards,
> >
> > Art Johnson
> > Senior Systems Analyst
> > PMC Prime Mover Controls Inc.
> > 3600 Gilmore Way
> > Burnaby, B.C., Canada
> > V5G 4R8
> > Phone: 604 433-4644
> > FAX: 604 433-5570
> > Email: art@p...
> > http://www.pmc-controls.com
> <http://www.pmc-controls.com>
> >
> >
> >
> > -----Original Message-----
> > From: dibosco [mailto:Robert.Wood@a...]
> > Sent: Wednesday, June 25, 2003 2:02 PM
> > To:
> > Subject: [motoroladsp] Crystal not working
> >
> >
> > Hi folks,
> >
> > I've just built up my new target board (first one
> with a 56Fxxx) and
> > am having no joy getting the crystal going - which
> is a bit
> depressing!
> >
> > I've got a 56F803, with an ACT crystal and 10M
> across the crystal,
> > just as the manual suggests and the EVM has.
> >
> > The crystal is an HC49/U - datasheet can be found
> on the link below.
> >
> >
>
http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html
>
>
<http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html>
>
> >
> > The voltages on the pins of the crytal sit at
> around 2.6V and Vcc
> (3.3V).
> >
> > I assume a blank device should still get the
> crystal oscillating? If
> > not, I guess the problem could well be with the
> JTAG set up.
> >
> > With that sketchy amount of info, anyone got any
> suggestions?
> >
> > Cheers,
> >
> > Rob.
> >
> >
> >
> > _____________________________________
> > Note: If you do a simple "reply" with your email
> client, only the
> author of this message will receive your answer.
> You need to do
> a "reply all" if you want your answer to be
> distributed to the entire
> group.
> >
> > _____________________________________
> > About this discussion group:
> >
> > To Join:
> >
> > To Post:
> >
> > To Leave:
> >
> > Archives:
> http://www.yahoogroups.com/group/motoroladsp
> <http://www.yahoogroups.com/group/motoroladsp>
> >
> > More Groups: http://www.dsprelated.com/groups.php3
>
> <http://www.dsprelated.com/groups.php3>
> >
> >
> > ">http://docs.yahoo.com/info/terms/
> <http://docs.yahoo.com/info/terms/>
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Sponsor
> >
>
<http://rd.yahoo.com/M%1812.3170658.4537139.1261774/D=egroupweb/S
>
05771855:HM/A64415/R=0/SIGt6t7kdo/*http://www.netflix.com/Defaul
> t?mqso`164784&partid170658>
> > <http://us.adserver.yahoo.com/l?
>
M%1812.3170658.4537139.1261774/D=egroupmail/S=:HM/A64415/rand5
> 759729>
> >
> > _____________________________________
> > Note: If you do a simple "reply" with your email
> client, only the
> author of this message will receive your answer.
> You need to do
> a "reply all" if you want your answer to be
> distributed to the entire
> group.
> >
> > _____________________________________
> > About this discussion group:
> >
> > To Join:
> >
> > To Post:
> >
> > To Leave:
> >
> > Archives:
> http://www.yahoogroups.com/group/motoroladsp
> <http://www.yahoogroups.com/group/motoroladsp>
> >
> > More Groups: http://www.dsprelated.com/groups.php3
>
> <http://www.dsprelated.com/groups.php3>
> >
> >
> > ">http://docs.yahoo.com/info/terms/> .


__________________________________


Yes, the first thing we tried was exactly the "recommended" circuit (Figure
15-1), with no capacitors. Extreme care was taken in the PCB layout (shortest
possible traces, good 4-layer board, etc.). It failed miserably.

We tried crystals with different characteristics, without success.

We tried everything in FAQ-20214, without success.

We spent weeks of effort to try to get the on-chip oscillator to start up
reliably at low temperatures, without success. We tried all possible
combinations in the oscillator circuit, with 0, 1, or 2 capacitors of various
values (10pF to 47pF) to ground (at EXTAL and/or XTAL), different feedback
resistor values from 1M to 22M ohms, and with or without the series resistor (Rs
in Motorola Application Note AN2049). None of these circuits started up
reliably at low temperatures, so we reluctantly decided (as strongly recommended
in Motorola Application Note AN2049) that the only solution was to use a
separate oscillator circuit that was guaranteed to start up at low temperatures.

That solved all of our problems.

Regards,

Art Johnson
Senior Systems Analyst
PMC Prime Mover Controls Inc.
3600 Gilmore Way
Burnaby, B.C., Canada
V5G 4R8
Phone: 604 433-4644
FAX: 604 433-5570
Email:
http://www.pmc-controls.com
-----Original Message-----
From: Charlie W [mailto:]
Sent: Thursday, June 26, 2003 5:50 PM
To: Pete Becher;
Subject: Re: [motoroladsp] Re: Crystal not working Please be aware that leg capacitors - most MCU
manufactures suggest 22pf-33pf - can kill crystal.
Motorola does not recommend leg caps for its DSP56F80x
devices.

Charlie W

--- Pete Becher <> wrote:
> Hi Rob,
>
> I have had problems with the crystal oscillator
> starting reliable
> also (at room temp). Out of 4 prototype boards I
> was testing 1 would
> start reliably, 1 would start randomly and 2 would
> not start at all.
> I did a lot of testing with various capacitors,
> resistors and
> different crystals with no good luck. I finally
> went with an
> external clock oscillator after reading Art's posts.
> All prototype
> and production boards have been working great since.
>
> Pete
>
> --- In , Hutchings
> William-p23437
> <william.hutchings@m...> wrote:
> > Rob -
> >
> > I do not know exactly how you have connected up
> the crystal, but we
> have a FAQ that might be of interest.
> >
> > FAQ-20214
> >
> >
> > Question:
> >
> > I am experiencing some crystal or resonator start
> up yield
> problems. Is their something you can recommend to
> resolve these
> issues ?
> >
> > answer
> >
> > Answer:
> >
> > The internal oscillator is designed to interface
> with a parallel-
> resonant crystal resonator in the frequency range
> specified for the
> external crystal in the data sheet. In the data
> sheet a recommended
> crystal oscillator circuit is shown. Follow the
> crystal
> supplier's recommendations when selecting a
> crystal, because
> crystal parameters determine the component values
> required to provide
> maximum stability and reliable start-up. The crystal
> and associated
> components should be mounted as close as possible to
> the EXTAL and
> XTAL pins to minimize output distortion and start-up
> stabilization
> time. The internal 56F800 oscillator circuitry is
> designed to have no
> external load capacitors present. As shown in the
> data sheet no
> external load capacitors should be used. If your
> circuit has external
> load capacitors these will cause crystal start up
> problems. Removing
> these capacitors should resolve your crystal start
> up issues
> >
> > If your circuit does not have external load
> capacitors and you are
> still experiencing a small yield issue you can also
> try limiting the
> ESR of value of the crystal you have chosen. The ESR
> of the crystal
> can affect the over all gain of the circuit and
> hence the start up
> characteristics. Lowering the ESR provides greater
> gain. An example
> would be if your crystal manufacturer specifies a
> maximum of 70 ohms
> ESR you could request a screen of the parts supplied
> to you for a
> maximum of 60 ESR and test to see if this resolves
> your start up
> yield issue. Crystal start up is affected by many
> different board,
> manufacturing, and crystal parameters and the values
> for ESR in this
> FAQ should not be taken as a maximum or recommended
> value.
> >
> >
> >
> > Related Products
> >
> > DSP56F826 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F826>
>
> > DSP56F827 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F827>
>
> > DSP56F801 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F801>
>
> > DSP56F803 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F803>
>
> > DSP56F805 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F805>
>
> > DSP56F807 <http://e-
>
www.motorola.com/webapp/sps/site/prod_summary.jsp?code=DSP56F807>
>
> >
> >
> > -----Original Message-----
> > From: Art Johnson [mailto:art@p...]
> > Sent: Wednesday, June 25, 2003 2:43 PM
> > To: dibosco;
> > Subject: RE: [motoroladsp] Crystal not working
> >
> >
> > Hi Rob,
> >
> > We had some oscillator startup failures (although
> not at room
> temperature) on our 56F807 products, so we went to
> an external
> oscillator. This is described in the following
> messages I sent on
> September 5 and 6 of 2002:
> > September 5, 2002, about 7:50am:
> > "RE: [motoroladsp] 56F807 expected life cycle"
> > September 6, 2002, about 6:53am:
> > "RE: [motoroladsp] Application Note AN2049 vs.
> 56800/56800E
> User's Manuals"
> >
> > We never had an oscillator startup failure at room
> temperature, so
> your problem may be a bad chip or a bad crystal.
> >
> > Regards,
> >
> > Art Johnson
> > Senior Systems Analyst
> > PMC Prime Mover Controls Inc.
> > 3600 Gilmore Way
> > Burnaby, B.C., Canada
> > V5G 4R8
> > Phone: 604 433-4644
> > FAX: 604 433-5570
> > Email: art@p...
> > http://www.pmc-controls.com
> <http://www.pmc-controls.com>
> >
> >
> >
> > -----Original Message-----
> > From: dibosco [mailto:Robert.Wood@a...]
> > Sent: Wednesday, June 25, 2003 2:02 PM
> > To:
> > Subject: [motoroladsp] Crystal not working
> >
> >
> > Hi folks,
> >
> > I've just built up my new target board (first one
> with a 56Fxxx) and
> > am having no joy getting the crystal going - which
> is a bit
> depressing!
> >
> > I've got a 56F803, with an ACT crystal and 10M
> across the crystal,
> > just as the manual suggests and the EVM has.
> >
> > The crystal is an HC49/U - datasheet can be found
> on the link below.
> >
> >
>
http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html
>
>
<http://www.act.co.uk/products/crystals/PTH_Crystals/actHC49_U.html>
>
> >
> > The voltages on the pins of the crytal sit at
> around 2.6V and Vcc
> (3.3V).
> >
> > I assume a blank device should still get the
> crystal oscillating? If
> > not, I guess the problem could well be with the
> JTAG set up.
> >
> > With that sketchy amount of info, anyone got any
> suggestions?
> >
> > Cheers,
> >
> > Rob.
> >
> >
> >
> > _____________________________________
> > Note: If you do a simple "reply" with your email
> client, only the
> author of this message will receive your answer.
> You need to do
> a "reply all" if you want your answer to be
> distributed to the entire
> group.
> >
> > _____________________________________
> > About this discussion group:
> >
> > To Join:
> >
> > To Post:
> >
> > To Leave:
> >
> > Archives:
> http://www.yahoogroups.com/group/motoroladsp
> <http://www.yahoogroups.com/group/motoroladsp>
> >
> > More Groups: http://www.dsprelated.com/groups.php3
>
> <http://www.dsprelated.com/groups.php3>
> >
> >
> > ">http://docs.yahoo.com/info/terms/
> <http://docs.yahoo.com/info/terms/>
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Sponsor
> >
>
<http://rd.yahoo.com/M%1812.3170658.4537139.1261774/D=egroupweb/S
>
05771855:HM/A64415/R=0/SIGt6t7kdo/*http://www.netflix.com/Defaul
> t?mqso`164784&partid170658>
> > <http://us.adserver.yahoo.com/l?
>
M%1812.3170658.4537139.1261774/D=egroupmail/S=:HM/A64415/rand5
> 759729>
> >
> > _____________________________________
> > Note: If you do a simple "reply" with your email
> client, only the
> author of this message will receive your answer.
> You need to do
> a "reply all" if you want your answer to be
> distributed to the entire
> group.
> >
> > _____________________________________
> > About this discussion group:
> >
> > To Join:
> >
> > To Post:
> >
> > To Leave:
> >
> > Archives:
> http://www.yahoogroups.com/group/motoroladsp
> <http://www.yahoogroups.com/group/motoroladsp>
> >
> > More Groups: http://www.dsprelated.com/groups.php3
>
> <http://www.dsprelated.com/groups.php3>
> >
> >
> > ">http://docs.yahoo.com/info/terms/> .


__________________________________
_____________________________________
Note: If you do a simple "reply" with your email client, only the author of this
message will receive your answer. You need to do a "reply all" if you want your
answer to be distributed to the entire group.

_____________________________________
About this discussion group:

To Join:

To Post:

To Leave:

Archives: http://www.yahoogroups.com/group/motoroladsp

More Groups: http://www.dsprelated.com/groups.php3 ">http://docs.yahoo.com/info/terms/


Many thanks to everyone who kindly helped with this issue. What finally got it
working was reading what someone else posted recently about the oscillator
not working without the analogue voltage also being applied.

Guess who hadn't connected analogue 3V3 to his board? ;-)

Thanks again to everyone for their suggestions, it's greatly appreciated.

Cheers,

Rob.