AVR works after pressing Reset Button

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I am using atmega328pb with external crystal 11.0592 MHz and seven segment and RGB LEDs. My devices works fine. But suppose I am having 300 devices and all are working fine and when I turn off and on main power then some time few devices start behaving randomly like by seeing seven segment display it pretends that device started working on 1 MHz instead of 11.0592 MHz. And some devices does not display anything but few segments of seven segment glows. And when I press the reset button then these devices start working fine. Some of these damaged devices work fine after giving power second time and some devices need to press reset button all the time after power on. Can anyone tell me what happening here?

Last Edited: Sun. Feb 24, 2019 - 05:26 AM
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Does your power supply meets the minimum rise time specification in the datasheet?

Are you using the Brown Out Detector?

What value capacitors are you using with the crystal?

How are your fuses set?

What is connected to your Reset pin?

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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What is the value of your pullup resistor on reset?  If you have a lot of noise, a small cap on reset can be helpful.

Are you initializing all of your variables & registers upon reset?

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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imrana326 wrote:

My devices works fine. But suppose I am having 300 devices...

 

Do you actually have 300 devices or is this a hypothetical question?

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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Is AVcc connected?  All power and ground pins?  Each pair properly decoupled?\

 

Does the same thing happen with a simple test program?  Are all variables properly initiated?  Is there a bootloader?

 

 

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Do you have by-pass caps on the power pins?

 

JC

 

Edit:

Sorry, just saw that Lee already mentioned that ne, also.

Last Edited: Sun. Feb 24, 2019 - 04:27 PM
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First of all thanks for reply.

1. Yes for rise time. I am using 19 ck + 65 ms in fuse bits and my power rise time is approx 2 ms.

2.yes I am using brown out detector at 2.7 v

3. 22 pf capacitors with crystal

4. My fuse bits Extended=0x05, High=0xDE, Low=0xFF

5. With my reset pin I have connected a button with 10k pull up resister and a capacitor 0.1 uF.

 

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I have used 10k resister with reset and along with a 0.1 uF capacitor. 

Yes i am initializing all variables and registers upon reset.

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Its not a hypothetical question. If I say Exact number then its 280 devices connected with one power supply of 24 v, 20 Amp.

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Yes AVcc is connected to 5 v.

All Power and Ground pin connected. And AREF is connected with GND with 100nf CAP.

No, I am not using bootloader.

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imrana326 wrote:

280 devices connected with one power supply of 24 v, 20 Amp.

 

What is the maximum current drawn by each assembly? Steady state average with 280 units and a 20Amp  supply would be 71.4mA. I think that you should show your circuit. Presumably you have a 5 volt supply on each unit. Is it a linear or switched regulator?

 

Please show your circuit and describe how the 24 volts/5 volts is distributed to the 280 units. Are they next to each other... or miles apart?

 

edited typos

Ross McKenzie ValuSoft Melbourne Australia

Last Edited: Mon. Feb 25, 2019 - 01:14 PM
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imrana326 wrote:
2.yes I am using brown out detector at 2.7 v

imrana326 wrote:
with external crystal 11.0592 MHz

The safe operating voltage at that frequency is 2.9V.  That is higher than the 2.7V you've selected for BOD, and the AVR core is fairly robust, but from an engineering standpoint it's too close.  Since you are running from 5V, you should select the 4.5V BOD.

 

imrana326 wrote:
it pretends that device started working on 1 MHz instead of 11.0592 MHz.
It's not pretending.  The 328pb has a "Clock Failure Detection Mechanism and Switch to Internal 8 MHz RC Oscillator in case of Failure".  Have a look at chapter 12 in the datasheet.

 

I'd guess that power is not stable/clean.

 

  • How far from the AVR is your crystal?
  • How fare are the caps?  What value are they?
  • What the load capacitance and ESR of your crystal?
  • Is this on a breadboard?

 

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

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"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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imrana326 wrote:
3. 22 pf capacitors with crystal
mega328PB doesn't have the full swing 16MHz crystal oscillator that mega328 and mega328P have.

As an oscillator becomes unstable (oscillates) its output amplitude increases and its frequency increases; might not reach 11MHz before the oscillator locks-in and/or internal reset is deasserted.

A system supervisor can hold the mega328PB in reset for a longer duration though am not certain that would solve the issue; excessive crystal oscillator load capacitance decreases the oscillator's safety factor (SF), excessive crystal capacitance decreases SF, excessive crystal ESR decreases SF.

There are third party mega328PB boards that have a resonator; haven't searched for a resonator that's an exact frequency match to the crystal.

IIRC, JoniS has a mega328PB board with a resonator.

 

AT15007: Differences between ATmega328/P and ATmega328PB (PDF, 3.1. Full Swing Oscillator)

via ATmega328PB - 8-bit AVR Microcontrollers

Pololu - A-Star 328PB Micro

mega328PB Testing Status | AVR Freaks (search that thread for mega324PB, resonator)

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Mon. Feb 25, 2019 - 05:57 PM
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Is this just a dumb led display connected to the AVR?  If, instead, it is a module, it might require some time to "stabilize" before you can write to it.  Where is your schematic?

 

it pretends that device started working on 1 MHz instead of 11.0592 MHz

What difference do you see? 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Maximum current drawn by each device is 30 mAmp. 24 v is given to 7 units and from each unit 20 devices is connected in parallel. And there is buck circuitry to convert 24 v into 5 v.

But the point is this problem once happened when I was using single device with one power supply.

Last Edited: Tue. Feb 26, 2019 - 11:43 AM
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 it pretends that device started working on 1 MHz instead of 11.0592 MHz

Why do you say that & why would it matter (any disruptive effect?)  Where is your schematic?

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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imrana326 wrote:

7 units and from each unit 20 devices is connected in series.

7 + (7*20) = 147.... not 280.

 

What do you mean 20 connected in series?

 

Circuit has been requested... several times... please.

Ross McKenzie ValuSoft Melbourne Australia

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Actually from each unit we have 2 nodes left and right and each node having 20 devices connected in parallel.

7*(20+20)=280.

I need to take permission for sharing the circuit. So, I am trying for permission.

Last Edited: Tue. Feb 26, 2019 - 11:42 AM
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I think post #13 explains your problem. I'd suggest you investigate this. 

 

Looking at the evidence - random failures suggest you are on the edge of a parameter. The crystal oscillators in some of the new AVR devices aren't quite as good as the older parts - it's in the datasheet. So, if the crystals are taking a bit longer than usual to start up and this is invoking the osc failure detect, then this explains your observations. You could add a little extra code to detect this and flash a led in a particular pattern or suchlike to quickly confirm. This way you have some hard evidence.

 

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I would start by looking at the power supply behavior in the faulty situation on a faulty board.

As already said, the power supply might not be stable enough in time. note that inrush currents can be a real pain in the ass.

have a look at the time from power application till the first instruction is executed.

the 10K 100nF at the reset line should keep the processor sleeping for a bit while power is coming on, but perhaps other parts are parasitically fed ( again we need a schematic to confirm/reject that).

o, and keep a good unit as a reference and see if there are strange differences that might explain.

 

note that with 30mA running current and good decoupling the inrush current will be a factor of that, more than 2 normally. if I have a factor of 3 current will be 90mA*280 is bigger than the 20Amps you SMPS can provide. It might go in fallback mode so less voltage and current until the problem is gone. causing your boards to not have a stable power supply when they start running. But a couple of scope measurements should be able to tell you that.

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avrcandies wrote:

 it pretends that device started working on 1 MHz instead of 11.0592 MHz

Why do you say that & why would it matter (any disruptive effect?)  Where is your schematic?

 

Why would it matter ?!!!!!!!!!!!

A device working on 1MHz

A device working on 11MHz

 

OFCURSE it matters!

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HI all,

I'm Vinay (colleague of Imran who posted this query).

So let me tell you the exact scenario. We're using a 24V to 5V buck converter circuit based on TI's TPS62175 in each of our boards for getting 5V supply for all peripherals and MCU.

The buck converter circuit can be seen here 

We are connecting all devices in parallel such that each device will get the same voltage and since the maximum current consumed by our device @24V is 30mA, we are connecting around 200 devices in parallel. And the power is supplied by a SMPS of rating (24V, 20A).

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Why would it matter ?!!!!!!!!!!!

A device working on 1MHz

A device working on 11MHz

 

OFCURSE it matters!

You certainly jump to  a conclusion!!  Whether it is 1 MHz or11 MHz, you turn on some 7 seg leds....they light up either way.  Other than flicker, a 7 segment disp should look the same & not have missing segments.  Even if you PWM them, the freq is probably high enough in both cases to not see any flicker.  So in this app, what difference does the processor speed make that is actually being observed?  There could  be some, or none at all!!

 

We are connecting all devices in parallel such that each device will get the same voltage and since the maximum current consumed by our device @24V is 30mA, we are connecting around 200 devices in parallel. And the power is supplied by a SMPS of rating (24V, 20A).

Elsewhere you are saying the units/devices are in series...is a unit a device?  Exactly how is everything connected?

 

With 200 units, you have 400 wires arriving at the power supply, correct?   If instead, they share the same bus , it will need to be perhaps 18 gauge or heavier wire.  What wiring are you using?

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Tue. Feb 26, 2019 - 09:08 AM
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avrcandies wrote:

Why would it matter ?!!!!!!!!!!!

A device working on 1MHz

A device working on 11MHz

 

OFCURSE it matters!

You certainly jump to  a conclusion!!  Whether it is 1 MHz or11 MHz, you turn on some 7 seg leds....they light up either way.  Other than flicker, a 7 segment disp should look the same & not have missing segments.  Even if you PWM them, the freq is probably high enough in both cases to not see any flicker.  So in this app, what difference does the processor speed make that is actually being observed?  There could  be some, or none at all!!

 

 

Mr Candies, The perfromance depends proportionaly to the clock speed. Now try to think a bit!!

 

EDIT: added exclamation mark at the end.

Last Edited: Tue. Feb 26, 2019 - 08:55 AM
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Mr Candies, The perfromance depends proportionaly to the clock speed. Now try to think a bit!! 

Eh, the performance of what?  Turn on an IO pin and turn on a relay.  Would it be any different at 1 MHz or 11MHz?  NOPE.

You might notice a difference if there is a lot of delay time, so that an 11x increase becomes notable.  Often speed is so fast,  that even 100x slower is still too fast to observe any difference (ex: read a pin, if high, light up led).  If it take 20microseonds or  220 microseconds, you won't see a performance difference.

As mentioned, 7-seg display don't care about clock speed, other than flicker if the speed gets way too slow.

You may keep thinking about it while we wait for the OP.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Tue. Feb 26, 2019 - 09:20 AM
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Candies, Its obvious its a commercial product, Clock speed, power consumption...200 units. sit down and think about it a bit wether it matters or no.

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Please be civil. Take a deep breath. The OP did NOT describe the situation correctly at all. His compatriot has arrived with more accurate information; parallel NOT serial for example. Let it unwind by itself.

 

@ Vinay  We are not going to download your webench file. Please capture its image into a pdf.

 

Ross McKenzie ValuSoft Melbourne Australia

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haven't searched for a resonator that's an exact frequency match to the crystal.

10pF load capacitors for this resonator above 8MHz :

https://www.mouser.com/datasheet/2/909/avx_02022018_PBRC-B-D_Series-1315572.pdf

via resonators, 11.0592MHz or 11.06MHz

https://www.mouser.com/Passive-Components/Frequency-Control-Timing-Devices/Resonators/_/N-6zu9h?P=1z0wo4hZ1yq9q5q

 

"Dare to be naïve." - Buckminster Fuller

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The OP has edited his reply #15. ?!

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I still would have a look at what the power supplies are doing.

My guess it that the 5V supply is going crappy the moment the boards are turned on. Note that you will see a voltage rise till the point were besides the input caps the SMPS starts working and thus the output caps also will get loaded, then most likely a 3rd current spike/supply dip the moment the processors all come out of reset and start executing code.

Is the 30mA when all 7 segment display LEDs are on, or 50% ?

 

I can hardly imagine that a 11MHz xtal will run at 1MHz. It can be an overtone, but then it would either be at 6,5 or 3,something not the magically mentioned 1 MHz.

Can it be that the fuses on the failing boards are not OK? that could mean either running at internal RC being 8mHz with clkdiv8 fuse set ending on 1MHz, or running on 11MHz xtal with clk div8 fuse set so ending at 1,4MHz which will feel like 1MHz.......

 

wonder if the OP and his colleague will return to give more information.

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meslomp wrote:

 

I can hardly imagine that a 11MHz xtal will run at 1MHz.

+1

Thanks.

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I do not understand avrcandies' attitude in this thread.

If a uC is configured to run from a crystal, and it does not, then that's an error, even if it's sole task in life was blinking a led. Wheter OP needs the clock cycles is not relveant in this respect.

 

Joey might be close:

joeymorin wrote:
imrana326 wrote: it pretends that device started working on 1 MHz instead of 11.0592 MHz. It's not pretending.  The 328pb has a "Clock Failure Detection Mechanism and Switch to Internal 8 MHz RC Oscillator in case of Failure".  Have a look at chapter 12 in the datasheet.

 

1MHz instead of 8MHz suggests CKDIV8 is programmed, but should that also divide the 11.0592MHz crystal ?

I'm not thinking too straight right now, but put the fuse settings in engbedded (for a 328P, while OP uses 328PB) and it suggests the boot reset vector is enabled, while OP claims no bootloader is used.

Fuse settings always confuse me, would somebody here be so kind to double check them?

 

Would it be logical to suspect a batch of faulty or marginally usefull crystals, maybe the SMD machine had a roll of wrong caps for the crystal. Are all faulty boards from the same batch?

A common problem with through hole crystals is a short between a PCB trace / hole and the metal housing of the crystal. This may change a bit due to movement when the reset button is pressed (mechanical stress on the PCB).

 

Is there a PPTC in the design?  These sometimes cause power supply voltages to sag, which can cause weird behaviour. (Especially if brown out is set too low for the used F_CPU).

Is there a correlation between the LED displays and the error? If there are power supply problems, they may only become prominent when a lot of LED's are on. You could try a power on self test with only 1 LED on at any time, and a "lamp" test with all LED's on. Monitor the power supply voltage with a scope. Is there any abnormality?

 

Can you post a picture of the board layout?

Relevant parts are: uC + decopling caps, layout of the circuit around the crystal, power supply section.

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

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Paulvdh wrote:
I do not understand avrcandies' attitude in this thread.

 

Neither do I ?!.

 

Thanks Paul for clarifying things, I dont understand when people says the 1MHZ frequency or 11MHz frequency doesnt matter and then trying to defend this idea...

 

Anyway, The OP needs clearly to show a picture of his board layout.

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Everything is connected in parallel connection. The power supply of 24V is shared by all devices. The gauge of the wire is 24AWG. 

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22pF load capacitors for 11.0592MHz crystal.

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The guys here and almost everyone are asking for something physical, a clear layout...otherwise it doesnt make sense

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vrgdubey wrote:
Everything is connected in parallel connection. The power supply of 24V is shared by all devices. The gauge of the wire is 24AWG.

Thanks for updating the thread, can you tell us the average length of wire from the power supply to the units that are failing? 

A picture of the setup may also help us see the situation.

 

Jim

 

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Last Edited: Tue. Feb 26, 2019 - 01:53 PM
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CKDIV8 fuse bit is not programmed. Certainly, BOOTRST fuse is programmed. But we've not written any bootloader. There is no PPTC in the design.

The LED display is glowed by glowing one segments each time (for persistence of vision method). So hardly 9mA current is consumed per GPIO of ATmega328PB. The crsyal is not thru hole, its surface mounted HC49US package and is placed very close to MCU with 22pF capacitors of COG/NPO ratings. AVCC is connected to 5V. There is 0.1uF decoupling capacitor between VCC and GND of MCU. AREF pin is coupled to GND via a 100nF cap. Reset pin is connected to a reset button along with 4.7k resistor pulled up to 5V along with 0.1uF capacitor. Brown out is set to 2.7V. 

Clock fault fuse bit is also not programmed. So the behavior which is discussed by guys that "because of clock failure the MCU is running on internal 8MHz oscillator and with CKDIV8, we are getting 1MHz clock" is completely ruled out. That's why this issue is bothering us. 

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ki0bk wrote:

vrgdubey wrote:
Everything is connected in parallel connection. The power supply of 24V is shared by all devices. The gauge of the wire is 24AWG.

Thanks for updating the thread, can you tell us the average length of wire from the power supply to the units that are failing? 

A picture of the setup may also help us see the situation.

 

Jim

 

I don't have the picture right now. Bu the maximum length of the wire is 10m.

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OP ruled out the possibility of showing any physical setup, nor schematic...nor board, nothing at all.

 

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imrana326 wrote:

I am using atmega328pb with external crystal 11.0592 MHz and seven segment and RGB LEDs. My devices works fine. But suppose I am having 300 devices and all are working fine and when I turn off and on main power then some time few devices start behaving randomly like by seeing seven segment display it pretends that device started working on 1 MHz instead of 11.0592 MHz. And some devices does not display anything but few segments of seven segment glows. And when I press the reset button then these devices start working fine. Some of these damaged devices work fine after giving power second time and some devices need to press reset button all the time after power on. Can anyone tell me what happening here?

 

If you repeat this, the devices that fail are always the same, or random?

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El Tangas wrote:

imrana326 wrote:

I am using atmega328pb with external crystal 11.0592 MHz and seven segment and RGB LEDs. My devices works fine. But suppose I am having 300 devices and all are working fine and when I turn off and on main power then some time few devices start behaving randomly like by seeing seven segment display it pretends that device started working on 1 MHz instead of 11.0592 MHz. And some devices does not display anything but few segments of seven segment glows. And when I press the reset button then these devices start working fine. Some of these damaged devices work fine after giving power second time and some devices need to press reset button all the time after power on. Can anyone tell me what happening here?

 

If you repeat this, the devices that fail are always the same, or random?

 

This has been observed randomly.

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Well, it really seems some problem with the power supply, right? What if you connect just half of the devices? Do you still get the problem?

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El Tangas wrote:

Well, it really seems some problem with the power supply, right? What if you connect just half of the devices? Do you still get the problem?

 

Yes it is still random. Sometimes we face the problem even with the single device connected to power supply.

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vrgdubey wrote:
This has been observed randomly.

That does suggest that your operating on the edge, have you tried changing the BOD to 4.2v level to see if the issue changes?

One other suggestion is to add a delay early in the code to allow the power to stabilize before starting normal operation (0.5 sec), but that would take more effort then changing the BOD fuse.

 

Jim

 

 

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Ok, so it's an individual board design problem, then. Do you think it might be the crystal, as people have suggested here?

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ki0bk wrote:

vrgdubey wrote:
This has been observed randomly.

That does suggest that your operating on the edge, have you tried changing the BOD to 4.2v level to see if the issue changes?

One other suggestion is to add a delay early in the code to allow the power to stabilize before starting normal operation (0.5 sec), but that would take more effort then changing the BOD fuse.

 

Jim

 

 

No, I haven't tried with BOD 4.2V. I'll definitely check it. 

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vrgdubey wrote:
The crsyal is not thru hole, its surface mounted HC49US package and is placed very close to MCU with 22pF capacitors of COG/NPO ratings.
22pF is approximately mid-range for HC49 crystals.

From mega324PB Xplained Pro schematic :

 

"Dare to be naïve." - Buckminster Fuller

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El Tangas wrote:

Ok, so it's an individual board design problem, then. Do you think it might be the crystal, as people have suggested here?

Nope, the crystal is not the issue otherwise other devices won't work properly. There is something else.

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XC200, 16.0MHz, Epson Toyocom, TSX-3225 16.0000MF09Z-AC3, 16MHz uXtal, 3.2 x 2.5 mm SMD, CL=9pF, 15PPM, ESR=80ohm(Max.

 

"Dare to be naïve." - Buckminster Fuller

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Can you post a link to the datasheet for the xtal used in your board?

As gchapman posted above, it may be your xtal caps are too large for reliable operation.  Details matter in these situations.

 

Jim

 

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