Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: nm1 on February 07, 2011, 09:03:46 PM

Title: Broken microcontroller? ($50 robot)
Post by: nm1 on February 07, 2011, 09:03:46 PM

Hi there, i'm new to robot making and I think there is a problem with the atmega 8 that I am using.
I completed the tutorial and successfully programmed the atmega 8 but the circuit would occasionally short out
thanks to my bad soldering, so I took most of the components off the board and re soldered every thing back (I took out the atmega first).

now after I re insert the atmega it will not work, and my multi meter is reading that all of the pins are connected to each other, where as before I inserted the atmega there was no shorts in the circuit.

I was wondering if I need to get a new atmega or if there is another problem.

any help will very much appreciated.
thanks

Title: Re: Broken microcontroller? ($50 robot)
Post by: HDL_CinC_Dragon on February 07, 2011, 10:37:54 PM

If youre DMM says all your pins are connected to eachother then thats your problem. Theyre all shorted out! Do you mean the pins on the socket are all reading short or the pins on the ATMEGA alone are reading short?

Try to make sure you use very thin solder when soldering to prevent excess build up at the solder sight. I use .032 60/40 with a very fine tip soldering iron and I get perfect solder joints every time! I had to re-solder my board several times at first though >_< I think I fried either 1 or 2 AT MEGA8s before I got it right lol. Just take eeeeetra care in your connections. If your 10000% confident your connections are good and your MCU still wont work, youll probably have to get a new one :-\ I made a seperate side circuit at one point too where its single solitary purpose was to talk to the MCU. It had no extra pins connected or anything. Give that a shot?

Title: Re: Broken microcontroller? ($50 robot)
Post by: nm1 on February 07, 2011, 11:37:15 PM

Thanks for the advice,
yeah its the pins on the atmega alone that are shorted.
I made the extra circuit just for the chip and that doesn't work either
so it must be the micro controller.
cheers

Title: Re: Broken microcontroller? ($50 robot)
Post by: rbtying on February 07, 2011, 11:48:31 PM

You should probably just get another ATMega - they're cheap enough that buying one isn't much of a cost, and an extra microcontroller often comes in handy.  Realistically, try supplying power (on a breadboard, maybe - no soldering) to +5v, GND, and RST only, and then trying to program it. 

Title: Re: Broken microcontroller? ($50 robot)
Post by: nm1 on February 09, 2011, 07:38:27 PM

thanks. I bought a few more microcontrollers but resetting didn't work anyway