What is the problem?

G'Night

Can the atmega actually source/sink the current needed by the display? maybe it's functioning within acceptable parameters to start with but it's probably becoming oversaturated and getting hot resulting in brownouts?

9v batteries don't supply a great amount of power either so definately a nicely sized smoothing cap on the power rails wouldn't go amiss either.

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

edit:

Do you have a multimeter to check the voltages?

If you are using a 7805, when they get hot they also start pulsing on and off so just check to make sure it's capable of supplying the current you need and also a temperature check while it's in operation would remove that doubt.

Lucie

The other link to the previous post suggests that he has a problem whenever the servo(s) are attached.

Unfortunately in the previous post we only got partial information so until we get it all, its hard to say what is happening.

There are no series resistors on the anode side, but maye they are included in the common.

Unfortunately he hasn;t answered about the schematic errors, so we really need rishi2628 to read the various ansers and fill in the missing bits.

If he does use a multimeter, it won't show the spikes, but it will show the average voltage.

Mark

rishi2628

The syntax highlighting that Enrico is referring to is a little hidden.

It's a shame there isn't a simple icon, but we struggled to get it added, so it's better than nothing.

past you code, then highlight it all and

Select the >> symbol, then Syntax Highlighting, then C++

It does have issues with blank lines, and tries to make it Excel, but I'm sure you'll sort it out.

Mark

mcb1

clem57

balearicdynamics

Robert Peter Oakes

Ok here is the complete circuit with EVERYTHING. Please note a couple of things:-

1) I have not used capacitors with 7805, hope it does not cause any problem.

2)The 5 volt output from 7805 powers 2 pwm servos and the atmega328p microcontroller. It is also attached to the input buttons.

3)Even when i detach the servos from the circuit , the flickering still happens which is evident from the video.

4)I have attached 0.1uf capacitors to every switch including reset button to prevent debouncing.

5)I am using analog pins as output pins

6) Lastly if anybody hasn't seen the flickering problem them please visit the link below, and note that for 20 seconds it works ok, then the flickering start.

https://www.youtube.com/watch?v=hdxqWKZSfso

Now here is the complete circuit:-

(please open it in new tab for a magnified image)

Many thanks, Rishi!

Well, first of all the power regulator without capacitors (and few other discrete components) is not the worth. At least it reduce the life of the battery, but it is very probable that one of the causes of the flickering depends on this, plus many other issues.

About the problem os the regulator, it is very probable that you incur in the ripple  issue. Whenever current is drawn from a regulator the voltage will start to drop but it is needed an amount of time before the regulator start increasing the voltage to compensate.  This is the ripple effect.  The amount of ripple will be larger if more current is drawn from the regulator so I suppose that when the system starts things seems going well but then the performances decreases as time go ahead; tale in account that the LM7805 as all this kind of regulators compensate the current with temperature dispersion so as time passes the system tend to be hot and the effect is more visibile..  To compensate the ripple effect just a capacitor provides a temporary bank of energy.  This is used to keep the voltage stable.

As source of inspiration please see the schematic in the image below.

Hope you are not offending if I prefer that this part is set correctly before we take in consideration more in depth the circuit. I think that your excessive simplification may really create serious unwanted behavior to your system.

Enrico

Why do you automatically discount multiplexing? Just because it worked one place does not mean it works in ALL places... You could have affected other wires while hooking up from the old Uno. Many factors are at play all the time. Check out for the obvious before looking for the sublime.

@clem57 to be honest I have not understood

brishisharma happy that you have solved the problem!!!

Reading the past posts I see that wrote:

Do you have a multimeter to check the voltages?

If you are using a 7805, when they get hot they also start pulsing on and off so just check to make sure it's capable of supplying the current you need and also a temperature check while it's in operation would remove that doubt.

but unfortunately we had not yet your full circuit

It's usually better to not power the servo's from the same source as the microcontroller but it is entirely possible with the right design. Most linear voltage regulator circuits should be built around a setup similar to the one balearicdynamics posted above with a small ceramic capacitor to smooth high frequency distortions and a larger electrolytic capacitor to provide extra power when needed.

Moving on from, powering the servos from there directly and then placing a diode between there and your microcontroller with another capacitor after it will give your logic circuit it's own independent power reserve which would help prevent it from resetting during times of heavy load.

I used this setup in one of my small robots that used 2 servo's powered from the same regulator as the logic and very rarely have power issues with it. They will occur if the servo's are pushed to their stall torque for any lengthy period of time but if thats happening then you should become more concerned over the possible damage to the serbo's and redesign the system around that.

Lucie