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ARM alive??? please help!

Started by omkar vyas June 20, 2006
how to recognize ARM lpc2104 is working or dead?
i have designed a board for lpc2104 but it is not working what are the all possibilities i will have to check?

1.core voltage is 1.8 volt it is getting it
2.secondly 3.3 volts to two pins it is also getting
3.crystal is not working i dint know why?
4.which is the best method of troubleshooting?

5.are there standard steps to follow?

please help !!!


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An Engineer's Guide to the LPC2100 Series

omkar vyas wrote:
> how to recognize ARM lpc2104 is working or dead?
> i have designed a board for lpc2104 but it is not working what are the
> all possibilities i will have to check?
>
> 1.core voltage is 1.8 volt it is getting it
> 2.secondly 3.3 volts to two pins it is also getting
> 3.crystal is not working i dint know why?

The oscillator may have been shut-down by the cpu so one way to check if
it does work is to hold the cpu in reset and scope the xtal. Take into
account that signal is not a square-wave but a sine wave with swing of
~1.5V on the output and a smaller signal of around ~1.3V on the input.

BTW, make sure that all the flux is cleaned away from the crystal
connections as some fluxes tend to be slightly conductive and the
oscillator circuit is highly sensitive.

> 4.which is the best method of troubleshooting?
You have already done some of the basics but you should scope the power
lines to see that they are clean. Check the reset signal and make sure
it is working properly. Bear in mind that there are signals that control
debug modes so DBGSEL needs to be low to operate normally.

Are all your grounds connected?

>
> 5.are there standard steps to follow?
>
> please help !!!
*Peter*
.
> 5.are there standard steps to follow?

You've started down the first 4 steps.

The key is the crystal not oscillating-

Also check the GND connections.

If its still not oscillating, check the power being drawn by the 2104.
I find the total for 1.8 and 3.3V supplies is about 15mA for an
unprogrammed part. This may be difficult to measure depending on your
circuit.

I'd be suspicious if the power consumption was more than 50mA that the
part may be dead. If its 0, then its probably not connected.

The oscillator should work even when RESET is low. Basically that
circuit is an inverter. You could try pulling X1 up with a 1K
resistor and see if X2 goes low, and if you pull X1 to GND X2 should
go high.

--- In l..., omkar vyas wrote:
>
> how to recognize ARM lpc2104 is working or dead?
> i have designed a board for lpc2104 but it is not working what are
the all possibilities i will have to check?
>
> 1.core voltage is 1.8 volt it is getting it
> 2.secondly 3.3 volts to two pins it is also getting
> 3.crystal is not working i dint know why?

That, of course, is your first major problem, since it can not work
without the oscillator. If the crystal was dropped, or damaged while
soldering, it may be cracked. If it is cracked, it will not oscillate.
If you are in a lab that has a network analyzer, you can test the
crystal. Otherwise, you could try substituting a new crystal. But
first, it is probably best to just be sure that there are no
underetched circuit board traces in the oscillator circuit, and that
there is no flux contamination there.

-- Dave

as i have posted previously i have developed ARM lpc 2104 board and its not working
1.now i have checked Flux i have cleaned it.
2.i have checked all ground connections.
3.crystal works fine if i connect some another module say 8051 it means that my crystal is working but it is not working with ARM
4.reset i have checked 10k resistance and 1 micro farad tantalum capacitor is i am using so it gets charged up by taking time of 30milliseconds
5.supply 1.8v and 3.3volts are working fine

crystal is ok but as i use my ARM module with the crystal that crystal does not osculate...

still ARM lpc 2104 is not working!

Does ARM have any pin which says it is working or not?

thankx!
omkar!


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As far as I know, there's nothing you can do without the
oscillator running. The "lowest common denominator"
of functionality is reading things like processor ID
over the JTAG interface. But my understanding is that
the JTAG signals are synchronised by the processor
clock.

I assume that you're using a X10 or X100 probe when
looking at the crystal. It is very easy for an
oscilloscope probe to *stop* an oscillator from working!

What DC voltages do you get on the oscillator pins?
Please tell us.
This could diagnose (a) leakage if there is an imbalance
and (b) what voltage is getting to the core.

You could try removing the crystal and injecting an
external oscillator signal of 1 - 30 MHz, >200 mV rms,
through a capacitor between 1000 pF and 100 pF into the
X1 pin. This should appear inverted on the X2 output.
With this singing, you could then try the JTAG interface.

-----

I would normally ask this question when dealing with
PIC microcontroller designs (where users have less
practical experience):
You imply this is your own board design. Not wishing
to insult your intelligence, is the layout around the
cystal very direct? And have you connected all the
supply and ground pins up? And does every power pin
have its own 0.1 uF decoupling capacitor within 5 mm
of that pin and an equally direct ground connection?
I don't know how much of the above is absolutely
necessary for reliable microcontroller operation.
But without question I would put such components
in the system.
(There was recent criticism from one contributor when
another person said that one should have a separate
IC to provide a clean reset signal. For small runs,
the risk of wasting time and effort where a system
is inadequately decoupled or not cleanly reset can
easily exceed the additional cost of those components).

Hope this helps,
Danish
--- In l..., omkar vyas wrote:
>
> as i have posted previously i have developed ARM lpc 2104 board and
its not working
> 1.now i have checked Flux i have cleaned it.
> 2.i have checked all ground connections.
> 3.crystal works fine if i connect some another module say 8051 it
means that my crystal is working but it is not working with ARM
> 4.reset i have checked 10k resistance and 1 micro farad tantalum
capacitor is i am using so it gets charged up by taking time of
30milliseconds
> 5.supply 1.8v and 3.3volts are working fine
>
> crystal is ok but as i use my ARM module with the crystal that
crystal does not osculate...
>
> still ARM lpc 2104 is not working!
>
> Does ARM have any pin which says it is working or not?
>
> thankx!
> omkar!

----- Original Message -----
From: "Julian Heller"
To:
Sent: Wednesday, June 21, 2006 7:58 AM
Subject: Re: [lpc2000] still question ARM alive??? please help!
> ----- Original Message -----
> From: "omkar vyas"
> To: "probs"
> Sent: Wednesday, June 21, 2006 7:45 AM
> Subject: [lpc2000] still question ARM alive??? please help!
> as i have posted previously i have developed ARM lpc 2104 board and its
> not working
> 1.now i have checked Flux i have cleaned it.
> 2.i have checked all ground connections.
> 3.crystal works fine if i connect some another module say 8051 it means
> that my crystal is working but it is not working with ARM
> 4.reset i have checked 10k resistance and 1 micro farad tantalum
> capacitor is i am using so it gets charged up by taking time of
> 30milliseconds
> 5.supply 1.8v and 3.3volts are working fine
>
> crystal is ok but as i use my ARM module with the crystal that crystal
> does not osculate...
>
> still ARM lpc 2104 is not working!
>
> Does ARM have any pin which says it is working or not?
What value capacitors are you using with the crystal and what is the
frequency?

Leon

hi Leon,
i am using 15pf;with the crystal of 11.0592 Mhz!
ya n as Danish have asked i am using X10 mode of oscilloscope probe.
dc voltage level at pins X1 = - 0.009(minus) ,X2 = -0.004(minus).

>>You imply this is your own board design. ya this is my first design of microcontroller
>> is the layout around the
cystal very direct?
-yes it is direct
>> And have you connected all the supply and ground pins up?
-yes i have
>> And does every power pin
have its own 0.1 uF decoupling capacitor within 5 mm
of that pin and an equally direct ground connection?
-yes but not all
simple RC network is used for reset

Leon Heller wrote: ----- Original Message -----
From: "Julian Heller"
To:
Sent: Wednesday, June 21, 2006 7:58 AM
Subject: Re: [lpc2000] still question ARM alive??? please help!

> ----- Original Message -----
> From: "omkar vyas"
> To: "probs"
> Sent: Wednesday, June 21, 2006 7:45 AM
> Subject: [lpc2000] still question ARM alive??? please help!
>
>
> as i have posted previously i have developed ARM lpc 2104 board and its
> not working
> 1.now i have checked Flux i have cleaned it.
> 2.i have checked all ground connections.
> 3.crystal works fine if i connect some another module say 8051 it means
> that my crystal is working but it is not working with ARM
> 4.reset i have checked 10k resistance and 1 micro farad tantalum
> capacitor is i am using so it gets charged up by taking time of
> 30milliseconds
> 5.supply 1.8v and 3.3volts are working fine
>
> crystal is ok but as i use my ARM module with the crystal that crystal
> does not osculate...
>
> still ARM lpc 2104 is not working!
>
> Does ARM have any pin which says it is working or not?
>
>
What value capacitors are you using with the crystal and what is the
frequency?

Leon

---------------------------------
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----- Original Message -----
From: "omkar vyas"
To:
Sent: Wednesday, June 21, 2006 9:40 AM
Subject: [lpc2000] still question ARM alive??? please help!
> hi Leon,
> i am using 15pf;with the crystal of 11.0592 Mhz!

That might be the cause of your problem, a much larger value is required! I
use 56 pF with a 10 MHz crystal. There is a table with recommended values in
the documentation.

Leon

hi Leon,
now i have changed crystal capacitors to the value 56pf still i didn't get the crystal frequency oscillations! :-(

now i have created two modules of ARM only but for module one i got frequency at its X1, and x2. but i guess this processor is dead coz accidentally one of us have given 4.22volts to the ARM core i think this have damaged that ARM but now once again i have developed the new board with proper components so now it is the case that i do not get the freq at x1 and x2!!
remaining all conditions are same as first module!

two identical ARM lpc 2104 one is suffered from accident of 4.22 volts to core
and other is not getting crystal frequency at x1 x2!

which thing says that ARM is working?

thankx!

Leon Heller wrote: ----- Original Message -----
From: "omkar vyas"
To:
Sent: Wednesday, June 21, 2006 9:40 AM
Subject: [lpc2000] still question ARM alive??? please help!

> hi Leon,
> i am using 15pf;with the crystal of 11.0592 Mhz!

That might be the cause of your problem, a much larger value is required! I
use 56 pF with a 10 MHz crystal. There is a table with recommended values in
the documentation.

Leon

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