Problem with ATmega32A reset when power down.

[veerubiji]

Problem with ATmega32A reset function when power down.

Hi,

I am new to microcontroller programming, I am confusing with reset function. I have one external Reset circuit (using 220nf capacitor and 56k resistor in parallel) to Reset microcontroller which is working good.

When power-off and power-on the microcontroller is not functioning. When i press external reset button then it is working. I didn't understand what might be the problem why it is not starting automatically when power on? I need to press external reset button always when i lose power.

I checked the fuse bits and it seems everything ok.

I want to know do i need to write any code for this to run the microcontroller when power-on? do i need to set any registers?

Please can anyone help me with this.

 

[FoxyRick]

Try disconnecting your reset circuit from the reset pin - leave the reset pin unconnected. See if the chip now powers up correctly.

The ATmega should do an internal power-on reset when you apply voltage. As soon as the voltage rises above the threshold, an internal reset pulse is started and ended by an automatic timer. If it does not start up properly then something is interfering with that. That could be your external reset circuit, or a poor power supply, but if the circuit resets manually and starts properly, then I would suspect your reset circuit.

Your reset circuit sounds unusual - can you post a schematic of it?

 

[veerubiji]

Hi,

Thanks for your reply, please find the attached file to see the schematic. But you need to zoom it to see properly.

What about MCUCSR settings? I have BODEN, CKOPT, JTAGEN, SPIEN as enabled and BODLEVEL as 2.7 v.

 

[FoxyRick]

Take a look at this document for a recommended reset circuit:

http://www.atmel.com/images/doc2521.pdf

 

[odongkerz]

Try use capacitor 0.1uF Tantalum and 10K resistor.


With that circuit, i never have any problem with power on or off.