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ATMega328-pu not responding on stand-alone PCB?


My ATMega328 based circuit is similar to the stand-alone Arduino design shown here. However even when I run a simple blink program the LED at pin 13 does not blink and I get no response from the microcontroller. I have tried the same circuit on a breadboard and it worked well. However when I transferred this on to the PCB there is no output.

I've checked the continuity and all the coppertraces seem to be fine. I program the chip using my Arduino Uno board and place it in the circuit. This works on the breadboard but not on the PCB.

I have attached the pictures of the PCB and a schematic diagram for reference. I'm completely stumped as to what the problem might be and would greatly appreciate any help.

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Your schematic shows no ground to the processor or its crystal components, or anything else that needs a ground !

It's nice to meet a grateful member who is intent on solving and learning.

Too many newbies sadly want it done for them for with no effort on their part.

Kudos to you Droid !

+1

ATMega.jpg
r5sb (author)  iceng1 year ago

Hey iceng, thanks for pointing that out! I had made some changes to that schematic before converting it to a layout and had connected all the grounds.

I've attached the PCB layout here and have marked the GND, 5V o/p and 10V i/p paths. I would really appreciate some fresh eyes taking a look at the layout as i can't seem to find what's wrong.

Thanks

layout (2).png

Ground still missing on crystal caps

+1

r5sb (author)  iceng1 year ago

Thanks steveastrouk, I soldered a wire from the capacitor ground to the common ground and it worked !

Thank you for the improved layout iceng, this is the first PCB i've printed so your tips will be very valuable in future PCB prints !

iceng r5sb1 year ago

Added three o.1uF ceramic filter caps, std to suppress uP power spikes.

Ground traces are the heaviest conductors power traces are thicker too.

The two uP ground pins are as short as possible. Added a jumper to overcome a trace condition. Many of your IC pins were shorted together.

I like to make pin_1 of my IC's a square for easy assembly and diode Anodes for the same reason.

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r5sb (author)  steveastrouk1 year ago

Thanks for your reply steveastrouk! I had made that change in the schematic and converted it to a PCB. The schematic I've attached shows that there is a ground connection for all (atleast I think it does :p). If I'm not mistaken then the ATMega328 has pins 22 and 8 connected internally (GND pins) ?

Here's my layout that is printed on the PCB. I've marked the Ground line and the 10V input and 5V output of the regulator.

Thanks!

layout (2).png