microcontroller misbehaving

[Pranav Dosajh]

Hi

Currently I am working on a weight based system using atmega32. everything works fine until a high powered motor or pump is switched on, the controller starts to misbehave i.e. it starts taking input on its own and works erratically.

I thought the problem is with supply so i separated the supply and used a constant voltage transformer
still the result is same.

I cannot figure out what is going on please help!!!!

 

[Ogu Reginald]

Hope you wrote a logic 1 in your code to make the input pins well defined?
Are you by any means using external pull up resistor?

 

[Pranav Dosajh]

Hope you wrote a logic 1 in your code to make the input pins well defined?
Are you by any means using external pull up resistor?

the problem is not the software everything works fine i think the issue is interference can you tell me some methods to reduce interference due to emi

thanks

 

[ravindragudi]

You have to share more information about the PCB or system you are working on. Like schematics, the interface of motor to PCB with micro, routing of any cable for the motor and power supply etc ... a picture of this will also be helpful.

 

[Pranav Dosajh]

thanks for the help appreciate it but the microcontroler is not operating any high voltage devices the problem is they are near by the microcontroller as and when these are switched on the microcontroller starts misbehaving i tried taking out the load cell signals but still it starts to misbehave. i dont have a clue whats wrong

 

[andre_luis]

i dont have a clue whats wrong

Had you read the previous reply ?

You have to share more information about the PCB or system you are working on. Like schematics

 

[Ogu Reginald]

Try adding a 100uF capacitor near the microcontroller between the VCC and the ground.

 

[rogerynt]

The problem is caused by harmonics when motor spins. You can do following tests to prove it.

1.) Split microcontroller power, ground with motor power, gnd at power input ( assume motor has an on/off control circuit )

2.) Add big reservoir cap. as close to mcu power as possible

3.) Cover microcontroller circuit by a metal shield can ( Make sure the shield can has good ground )

If problem still happens then the interference may leak from motor to microcontroller through control path. If this is the case, you has increase the control resistor or isolate it completely

 

[andre_luis]

The problem can be related either to the integrity of the signals/power busses due to layout aspects or even to some issue on circuit conception, but while the op not provide more details, the range of possible reasons will keep extensive.

 

[austx2015]

I'm just guessing, it could be caused by the motor driver power drawn from the power supply.