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hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

kanok53 wrote:
> hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.

Some more details on what you've done would be useful.

5V tolerance is really an input spec. It doen't mean the pins will
drive 5V.

Robert

--
http://www.aeolusdevelopment.com/

From the Divided by a Common Language File (Edited to protect the guilty)
ME - "I'd like to get Price and delivery for connector Part # XXXXX"
Dist./Rep - "$X.XX Lead time 37 days"
ME - "Anything we can do about lead time? 37 days seems a bit high."
Dist./Rep - "that is the lead time given because our stock is live....
we currently have stock."
------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, Robert Adsett wrote:
>
> kanok53 wrote:
> > hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.
>
> Some more details on what you've done would be useful.
>
> 5V tolerance is really an input spec. It doen't mean the pins will
> drive 5V.
>
> Robert
>
> --
> http://www.aeolusdevelopment.com/
>
> From the Divided by a Common Language File (Edited to protect the guilty)
> ME - "I'd like to get Price and delivery for connector Part # XXXXX"
> Dist./Rep - "$X.XX Lead time 37 days"
> ME - "Anything we can do about lead time? 37 days seems a bit high."
> Dist./Rep - "that is the lead time given because our stock is live....
> we currently have stock."
>
at first thanking you to response to my post.
actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by lpc2106's 3 pins in three different board. 2 of them working very nicely so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving the s1 of mux properly. but i've found no problem in either code(cz its the same program) or in hardware(cz i've tried in the same hardware by replacing only the mcu lpc2106). so what could be the problem?
thanks again in advance.

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

----- Original Message -----
From: "kanok53"
To:
Sent: Monday, May 18, 2009 10:44 AM
Subject: [lpc2000] Re: 5v tolerant feature of lpc2106
> at first thanking you to response to my post.
> actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by
> lpc2106's 3 pins in three different board. 2 of them working very nicely
> so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving
> the s1 of mux properly. but i've found no problem in either code(cz its
> the same program) or in hardware(cz i've tried in the same hardware by
> replacing only the mcu lpc2106). so what could be the problem?

Will a 74LS input work with a 3.3V CMOS output?

Leon

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

according the 74LS151 datasheet a minimun of 2.0v input is required for the device to work

Regards

Jean-Jacques
--- In l...@yahoogroups.com, "leon Heller" wrote:
>
> ----- Original Message -----
> From: "kanok53"
> To:
> Sent: Monday, May 18, 2009 10:44 AM
> Subject: [lpc2000] Re: 5v tolerant feature of lpc2106
> > at first thanking you to response to my post.
> > actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by
> > lpc2106's 3 pins in three different board. 2 of them working very nicely
> > so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving
> > the s1 of mux properly. but i've found no problem in either code(cz its
> > the same program) or in hardware(cz i've tried in the same hardware by
> > replacing only the mcu lpc2106). so what could be the problem?
>
> Will a 74LS input work with a 3.3V CMOS output?
>
> Leon
>

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, "leon Heller" wrote:
>
> ----- Original Message -----
> From: "kanok53"
> To:
> Sent: Monday, May 18, 2009 10:44 AM
> Subject: [lpc2000] Re: 5v tolerant feature of lpc2106
> > at first thanking you to response to my post.
> > actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by
> > lpc2106's 3 pins in three different board. 2 of them working very nicely
> > so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving
> > the s1 of mux properly. but i've found no problem in either code(cz its
> > the same program) or in hardware(cz i've tried in the same hardware by
> > replacing only the mcu lpc2106). so what could be the problem?
>
> Will a 74LS input work with a 3.3V CMOS output?

ya it works with a 3.3V CMOS output as 2 of my boards are still working. but as my another board got damaged(only one of those 3 pins which are driving selection line of mux) so i'm little bit worried about other two boards. I need the explanation of getting the pin damaged so that i can change my design if it demands. any hints of explanation of this matter will be helpful for me. thanks in advance.
>
> Leon
>

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

kanok53 wrote:
> --- In l...@yahoogroups.com, "leon Heller" wrote:
>> ----- Original Message -----
>> From: "kanok53"
>> To:
>> Sent: Monday, May 18, 2009 10:44 AM
>> Subject: [lpc2000] Re: 5v tolerant feature of lpc2106
>>> at first thanking you to response to my post.
>>> actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by
>>> lpc2106's 3 pins in three different board. 2 of them working very nicely
>>> so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving
>>> the s1 of mux properly. but i've found no problem in either code(cz its
>>> the same program) or in hardware(cz i've tried in the same hardware by
>>> replacing only the mcu lpc2106). so what could be the problem?
>> Will a 74LS input work with a 3.3V CMOS output?
>
> ya it works with a 3.3V CMOS output as 2 of my boards are still working. but as my another board got damaged(only one of those 3 pins which are driving selection line of mux) so i'm little bit worried about other two boards. I need the explanation of getting the pin damaged so that i can change my design if it demands. any hints of explanation of this matter will be helpful for me. thanks in advance.

A test like that provides very little evidence, but another poster
pointed out the threshold was 2V.

So, these are three identical boards populated in the same fashion?

What three pins are being used?

They only drive the mux selection lines?

If you are using standard output pins to drive only single logic inputs
then your pin did not fail because of the load it was expected to drive.
You are looking for something else (construction fault, static).

Robert
--
http://www.aeolusdevelopment.com/

From the Divided by a Common Language File (Edited to protect the guilty)
ME - "I'd like to get Price and delivery for connector Part # XXXXX"
Dist./Rep - "$X.XX Lead time 37 days"
ME - "Anything we can do about lead time? 37 days seems a bit high."
Dist./Rep - "that is the lead time given because our stock is live....
we currently have stock."
------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, Robert Adsett wrote:
>
> kanok53 wrote:
> > --- In l...@yahoogroups.com, "leon Heller" wrote:
> >> ----- Original Message -----
> >> From: "kanok53"
> >> To:
> >> Sent: Monday, May 18, 2009 10:44 AM
> >> Subject: [lpc2000] Re: 5v tolerant feature of lpc2106
> >>> at first thanking you to response to my post.
> >>> actually i'm driving mux(74ls151) selection line(s0,s1,s2) pins by
> >>> lpc2106's 3 pins in three different board. 2 of them working very nicely
> >>> so far. but one of it doesn't, cz one of the pin of lpc2106 is not driving
> >>> the s1 of mux properly. but i've found no problem in either code(cz its
> >>> the same program) or in hardware(cz i've tried in the same hardware by
> >>> replacing only the mcu lpc2106). so what could be the problem?
> >> Will a 74LS input work with a 3.3V CMOS output?
> >
> > ya it works with a 3.3V CMOS output as 2 of my boards are still working. but as my another board got damaged(only one of those 3 pins which are driving selection line of mux) so i'm little bit worried about other two boards. I need the explanation of getting the pin damaged so that i can change my design if it demands. any hints of explanation of this matter will be helpful for me. thanks in advance.
>
> A test like that provides very little evidence, but another poster
> pointed out the threshold was 2V.
>
> So, these are three identical boards populated in the same fashion?
>
> What three pins are being used?
>
> They only drive the mux selection lines?
>
> If you are using standard output pins to drive only single logic inputs
> then your pin did not fail because of the load it was expected to drive.
> You are looking for something else (construction fault, static).
>
> Robert
> --
> http://www.aeolusdevelopment.com/
>
> From the Divided by a Common Language File (Edited to protect the guilty)
> ME - "I'd like to get Price and delivery for connector Part # XXXXX"
> Dist./Rep - "$X.XX Lead time 37 days"
> ME - "Anything we can do about lead time? 37 days seems a bit high."
> Dist./Rep - "that is the lead time given because our stock is live....
> we currently have stock."
>
thanks for ur elaborated explanation.
yes, i've designed three boards identically for three robots.
i'm using p0.28, p0.29 & p0.30 for this purpose and surely as standard ouput, nothing else.
what do u mean by construction problem or static charge problem?

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

kanok53 wrote:
> thanks for ur elaborated explanation.

Spell your words out correctly please. You are not limited here by a
SMS buffer.

> yes, i've designed three boards identically for three robots.
> i'm using p0.28, p0.29 & p0.30 for this purpose and surely as standard ouput, nothing else.
> what do u mean by construction problem or static charge problem?

Construction problems are things such as shorts or opens. Poorly
soldered pins or solder bridges. Could be caused by poor construction
technique or via too close to pads. Check that you don't have a low
resistance path to ground.

Static charge problem. I am referring to damage caused by static
discharge into device pins. If you've changed the micro the mux vould
still be damaged.

One fairly basic technique for checking would be to remove the mux and
check to see if the micro's pin will toggle. That should also make it
easy to check for solder bridges where the mux used to be. A DMM will
help check for bridges elsewhere.

Robert

--
http://www.aeolusdevelopment.com/

From the Divided by a Common Language File (Edited to protect the guilty)
ME - "I'd like to get Price and delivery for connector Part # XXXXX"
Dist./Rep - "$X.XX Lead time 37 days"
ME - "Anything we can do about lead time? 37 days seems a bit high."
Dist./Rep - "that is the lead time given because our stock is live....
we currently have stock."
------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, "kanok53" wrote:
>
> hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.
>

The pins are only 5V tolerant if Vdd3 is present. There can be no situation when the external 5V logic is powered while the uC is not.

I tend to use 330 ohm series resistors between uC pins and external things. The resistance is low enough not to cause much signal degradation but high enough to limit current flow should the resistor be shorted to ground.

Look at the pins with a scope and see what is happening.

I doubt it is a problem but make sure the uC and the MUX share a common Vss,

Richard

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, Robert Adsett wrote:
>
> kanok53 wrote:
> > thanks for ur elaborated explanation.
>
> Spell your words out correctly please. You are not limited here by a
> SMS buffer.
>
> > yes, i've designed three boards identically for three robots.
> > i'm using p0.28, p0.29 & p0.30 for this purpose and surely as standard ouput, nothing else.
> > what do u mean by construction problem or static charge problem?
>
> Construction problems are things such as shorts or opens. Poorly
> soldered pins or solder bridges. Could be caused by poor construction
> technique or via too close to pads. Check that you don't have a low
> resistance path to ground.
>
> Static charge problem. I am referring to damage caused by static
> discharge into device pins. If you've changed the micro the mux vould
> still be damaged.
>
> One fairly basic technique for checking would be to remove the mux and
> check to see if the micro's pin will toggle. That should also make it
> easy to check for solder bridges where the mux used to be. A DMM will
> help check for bridges elsewhere.
>
> Robert
>
> --
> http://www.aeolusdevelopment.com/
>
> From the Divided by a Common Language File (Edited to protect the guilty)
> ME - "I'd like to get Price and delivery for connector Part # XXXXX"
> Dist./Rep - "$X.XX Lead time 37 days"
> ME - "Anything we can do about lead time? 37 days seems a bit high."
> Dist./Rep - "that is the lead time given because our stock is live....
> we currently have stock."
>
Thanks for suggesting me some nice solutions.
I'll keep your suggestion about the spelling in my mind next time.

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, "rtstofer" wrote:
>
> --- In l...@yahoogroups.com, "kanok53" wrote:
> >
> > hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.
> > The pins are only 5V tolerant if Vdd3 is present. There can be no situation when the external 5V logic is powered while the uC is not.
>
> I tend to use 330 ohm series resistors between uC pins and external things. The resistance is low enough not to cause much signal degradation but high enough to limit current flow should the resistor be shorted to ground.
>
> Look at the pins with a scope and see what is happening.
>
> I doubt it is a problem but make sure the uC and the MUX share a common Vss,
>
> Richard
>
"There can be no situation when the external 5V logic is powered while the uC is not."
I'm little bit concerned about this line. as my design involves separate vcc for uc and external components. and there are some cases where it might occur when the uc is not powered up but the external components are. so is it a serious problem for uc? and if yes, then how? please don't be angry on me as i've very little knowledge on electronics. thanks in advance.

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

> "There can be no situation when the external 5V logic is powered while the uC is not."
> I'm little bit concerned about this line. as my design involves separate vcc for
> uc and external components. and there are some cases where it might occur when
> the uc is not powered up but the external components are. so is it a serious
> problem for uc? and if yes, then how? please don't be angry on me as i've very
> little knowledge on electronics. thanks in advance.

The specification you are violating is listed on p26 of the datasheet:

http://www.standardics.nxp.com/products/lpc2000/datasheet/lpc2104.lpc2105.lpc2106.pdf

The input voltage limits are -0.5 to VDD(3V3)+0.5, so when the
uC power is off, the pins can not be driven by more than +/-0.5V.

I/O pins generally have protection diodes that get forward biased
when you over/under-drive the pins. If too much current flows
through these diodes, then they get damaged; sometimes in an
obvious way (they're dead), other times, they become flakey.

There a couple of solutions generally used to avoid damaging the
protection diodes; use a series resistor on the I/O, or use
external I/O buffers with tolerant inputs. A series resistor
limits the current flowing into the protection diode. However,
without a specification on how much current/power-dissipation
is allowed, using external buffers would be the more conservative
solution.

TI and Fairchild have a range of TinyLogic devices that are tolerant
of 5.5V or 6V on their pins independent of the power-supply being
powered. There are also multi-bit versions of these types of
devices. Bus-switches are also a possible solution.

The I/O sequencing issues you are experiencing are pretty
common in 'hot-swap' situations, where both power supplies and
I/Os come in contact with other live circuits. If you want to
learn more, Google 'hot-swap' and read some of the application
notes you find.

Cheers,
Dave

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

kanok53 wrote:
> --- In l...@yahoogroups.com, "rtstofer" wrote:
>> --- In l...@yahoogroups.com, "kanok53" wrote:
>>> hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.
>>>
>> The pins are only 5V tolerant if Vdd3 is present. There can be no situation when the external 5V logic is powered while the uC is not.
>>
>> I tend to use 330 ohm series resistors between uC pins and external things. The resistance is low enough not to cause much signal degradation but high enough to limit current flow should the resistor be shorted to ground.
>>
>> Look at the pins with a scope and see what is happening.
>>
>> I doubt it is a problem but make sure the uC and the MUX share a common Vss,
>>
>> Richard
>>
> "There can be no situation when the external 5V logic is powered while the uC is not."
> I'm little bit concerned about this line. as my design involves separate vcc for uc and external components. and there are some cases where it might occur when the uc is not powered up but the external components are. so is it a serious problem for uc? and if yes, then how? please don't be angry on me as i've very little knowledge on electronics. thanks in advance.

Possibly.

Richards idea of the current limiting resistor is good. Shutting off
parts of a circuit without using isolation is never easy since you have
to track down and deal with all the possible current paths and you have
to make sure all digital inputs are always in a defined state. Digital
isolation is fairly cheap and would let you cross voltage domains as
well. For example Analog Devices iCouplers

http://www.analog.com/en/interface/digital-isolators/products/index.html

That would also allow you to separate the I/O voltage domain from the
micro. Not a bad idea in a robot. The two sides of the isolator can
use different grounds. "fairly cheap" is in the eye of the beholder.

Robert

--
http://www.aeolusdevelopment.com/

From the Divided by a Common Language File (Edited to protect the guilty)
ME - "I'd like to get Price and delivery for connector Part # XXXXX"
Dist./Rep - "$X.XX Lead time 37 days"
ME - "Anything we can do about lead time? 37 days seems a bit high."
Dist./Rep - "that is the lead time given because our stock is live....
we currently have stock."
------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, Robert Adsett wrote:
>
> kanok53 wrote:
> > --- In l...@yahoogroups.com, "rtstofer" wrote:
> >> --- In l...@yahoogroups.com, "kanok53" wrote:
> >>> hi, i'm recently working on a project where i'm using LPC2106 uc. i've interfaced it with various ics which are powered by 5v supply but facing some problem in it. some of its pins which r driving some 5 volt powered pin of other ic, seem to be damaged. but olimex's datasheet clearly suggesting that LPC2106 has 5v tolerant I/O features. so what might be the fault in my case? thanks in advance.
> >>>
> >> The pins are only 5V tolerant if Vdd3 is present. There can be no situation when the external 5V logic is powered while the uC is not.
> >>
> >> I tend to use 330 ohm series resistors between uC pins and external things. The resistance is low enough not to cause much signal degradation but high enough to limit current flow should the resistor be shorted to ground.
> >>
> >> Look at the pins with a scope and see what is happening.
> >>
> >> I doubt it is a problem but make sure the uC and the MUX share a common Vss,
> >>
> >> Richard
> >>
> > "There can be no situation when the external 5V logic is powered while the uC is not."
> > I'm little bit concerned about this line. as my design involves separate vcc for uc and external components. and there are some cases where it might occur when the uc is not powered up but the external components are. so is it a serious problem for uc? and if yes, then how? please don't be angry on me as i've very little knowledge on electronics. thanks in advance.
>
> Possibly.
>
> Richards idea of the current limiting resistor is good. Shutting off
> parts of a circuit without using isolation is never easy since you have
> to track down and deal with all the possible current paths and you have
> to make sure all digital inputs are always in a defined state. Digital
> isolation is fairly cheap and would let you cross voltage domains as
> well. For example Analog Devices iCouplers
>
> http://www.analog.com/en/interface/digital-isolators/products/index.html
>
> That would also allow you to separate the I/O voltage domain from the
> micro. Not a bad idea in a robot. The two sides of the isolator can
> use different grounds. "fairly cheap" is in the eye of the beholder.
>
> Robert
>
> --
> http://www.aeolusdevelopment.com/
>
> From the Divided by a Common Language File (Edited to protect the guilty)
> ME - "I'd like to get Price and delivery for connector Part # XXXXX"
> Dist./Rep - "$X.XX Lead time 37 days"
> ME - "Anything we can do about lead time? 37 days seems a bit high."
> Dist./Rep - "that is the lead time given because our stock is live....
> we currently have stock."
>
thanks to all. it was really a great help for me. now i realize the problem and i'll correct them. thanks to all guys again.

------------------------------------



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

--- In l...@yahoogroups.com, "kanok53" wrote:

> > >> The pins are only 5V tolerant if Vdd3 is present. There can be no situation when the external 5V logic is powered while the uC is not.
> > >>
> > >> I tend to use 330 ohm series resistors between uC pins and external things. The resistance is low enough not to cause much signal degradation but high enough to limit current flow should the resistor be shorted to ground.
> > >>
> > >> Look at the pins with a scope and see what is happening.
> > >>
> > >> I doubt it is a problem but make sure the uC and the MUX share a common Vss,
> > >>
> > >> Richard
> > >>
> > > "There can be no situation when the external 5V logic is powered while the uC is not."
> > > I'm little bit concerned about this line. as my design involves separate vcc for uc and external components. and there are some cases where it might occur when the uc is not powered up but the external components are. so is it a serious problem for uc? and if yes, then how? please don't be angry on me as i've very little knowledge on electronics. thanks in advance.

The comment re: 5V tolerance only existing when Vdd3 is present comes from the datasheet, Section 7, "Limiting Values". It is probably more of a problem if the LS TTL is outputting to an ARM input. Basically, the TTL output would forward bias the clamp diodes on the pins and try to power the chip. This would probably allow more current to flow that the uC would accept.

Richard

------------------------------------



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