atmega not working when placed directly into my project - Page 1
Forum section: electronics / projects

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 27, 2013, 08:11:55 pm
content: hello, i have recently revived my nixie tube clock project and decided to see if i can repair the clock. i have done many fixes including breaking tracks replacing components and correcting traces but i have come to a dilemma.i currently have a slot of the nixie tube for an atmega328 toplug into and control the clock but when i plug the chip into it to does not however, if i plug the same atmega into an arduino board and bridge the gnd, +5, SCL and SDL (I2C) lines into the corresponding pins on my nixie tube clock it displays the time, reads all the I2C information and updates correctly which i ahve found to be a bit strange. could this be a case of the crystal on the project has gone bust or some other problem which i cannot think of. unfortunately i do not have an oscilloscope to probe the the crytal to see if its still ticking correctly but i do ahve a UT60E multimeter which supposedly can measure frequencys up to 1MHz but i cant get it to read anything above 50Hz am i connecting it wrong? (test leads to each pin on the crystal) or is it unable to read the crystal?any help on this would be great and i would like to get thick clock back in its case again.

author: bingo600
author_rank: Super Contributor
timestamp: August 27, 2013, 08:57:50 pm
content: Quote from: carbon dude oxide on August 27, 2013, 08:11:55 pmYou can't use a DMM to measure the Xtal Osc , it will load it to much.1: Did you remember to use 2 x 100nF bypass caps , one on each VCC's for the M328 ?2: Did you use ~22pF as Xtal loads ?3: If you have an AVR programmer you could try to switch the fuses to 8Mhz Internal clock , and rebuild the software for that freq , that would show if the external Xtal Osc is the problem. But will prob. also blow away the Arduino bootloader./Bingo

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 27, 2013, 09:28:06 pm
content: it has the bypass caps for the atmega and the caps for the crystal i made sure of that. and im using the arduino software currently and jut swapping the chip into my project.

author: Unknown
author_rank: Unknown
timestamp: August 27, 2013, 09:42:39 pm
content: Is the reset pin pulled up? Are the power and ground pins connected correctly? Put your multimeter probes on the actual pins in case you have a dodgy socket. TheAVR042 appnote(AVR hardware design considerations) may also contain some helpful hints.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 27, 2013, 09:59:37 pm
content: i have tested all the pins on the socket an they are all amking a connection to the board from the pins on the IC, the reset pin is pulled high using a 10k resistor and there is also a manual button.earlyer today i did fix a problem but in the process i think the 12V line hit the 5V line when i tested it. the whole cicuit is working fine apart from when i connect the atega328 into its designated socket but works fine when i ahve it in the arduino board and just jump the pins over.i have had the board working fine before without any problems...

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 28, 2013, 10:10:18 am
content: ok i have replaced the ccrystal, no change. I have also bridged out all the pins that are being used onto the arduino board including the power so it is just like it being plugged into the project itself and it works no problem. could it be that some of the unused pins (that are soldered in) could be causing the problem?

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: August 28, 2013, 06:27:19 pm
content: ok i Have fixed itturns out the markings on the capacitors for the crystal were wrong by a magnitude (or I ordered a different value or i am reading it wrong but meh) either way i found the problem when adding bits to a breadboard and i used the same caps as the project and noticed that it wa very sluggish and was taking a very long time to do anything, so i checked the caps again and tada there was the problem thanks bingo600 as you did say that could be the problem.its working now and looks goodif you want pics let me know

author: jancumps
author_rank: Unknown
timestamp: August 28, 2013, 06:48:42 pm
content: excellent piece of troubleshooting.want pics