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Atmega328P-PU (arduino uno) from breadboard to pcb

bobj6

Hello everybody.

 

I been working with an arduino uno for a few years now and i decide to make them standalone.

So i bought some Atmega328P-PU and start putting them on a breadboard with a Crystal and a few capacitors

I have loaded the BLINK example onto my Atmega chip and this works fine, The led blinks with an interval of aproximilly a 1/2 second.

 

Now this works i have solderd one onto a PCB.

I used a Voltage regulator (L7805ABV) to make 5 volts out of 12 volts.

the Atmega does get power and ground and the Crystal is also correct installed.

But when i start it up the led on pin 13 doesn't light up.

When I touch the plastic of the Atmega chip the led does ligt up, But flashes way to fast (Not the 1/2 a second it should).

 

does anyone have an idea what is going wrong here?

I thank you in advance.

 

Yours sincerly,

Bob

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  • 0 in reply to bobj6

    you should always have some de-coupling capacitors close to the 328 across the supply, from AVcc to gnd and Vcc to gnd, about 100nF (0.1uF) would suffice for that, and a bigger 10 - 100uF across the supply too on the board (Yes a 10uF in parallel with 0.1uF, it is not for the combined smoothing but the way capacitors internal composition react to different frequencies. the larger capacitor takes care of local smoothing and the smaller ones take care of higher frequency switching noise etc that the larger one will not adequatly handle.

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