Hi,
I try to made this
But at a first test the don't work.
Is the capacity of the crystal essential? I've a crystal of 18pF, and on a bought arduinoboard they will use a 22pF crystal.
Could that be the fault?
Gr.
Johan
There is an error in that page. Don't connect AREF to 5V.
The capacitors are critical, but 18pF is still okay.
Do you have 100nF decoupling capacitor to 5V and GND ?
You can use an Arduino Uno board to upload a sketch into an ATmega328p, and after that move that chip into the breadboard.
Could you make a photo to it ? So we can check the wiring ?
jmnijsse:
Is the capacity of the crystal essential? I've a crystal of 18pF, and on a bought arduinoboard they will use a 22pF crystal.
Could that be the fault?
Crystals have different needs for load capacitance. Some of them need 22pf to work, others 18pf, others 28pf. You should ask your crystal provider for the crystal datasheet.
If you want your life easier, buy a 16mhz resonator, it's and oscilator which includes cap.
If you want your life easier, buy a 16mhz resonator,
If you want an even easier life, buy a 16MHz resonator instead.
Is it wrong to set the 16MHz crystal (18pF) to ground with 22pF?
(16mhZ, 18Pf) / capacitors (22Pf)
I'm pretty sure you can't buy petaFarad devices.
:~.pF, I mean and you understand well...
jmnijsse:
:~.pF, I mean and you understand well...
I do understand well - I work on devices where frequencies are specified from mHz to GHz.
It's really important to know where your shift-key is.
Hmmm...
Caps-Lock problem...
MHz, pF - mhZ, Pf.
But: my question... 
18pF is fine. The difference with 22pF is 4pF. Do you know how much 4pF is ?
The 22pF is just an average that will make crystals work, allthough the crystals are different.
Thanks for the photo. I was expecting 10k resistor from 5V to reset and a button to ground.
The reset is active low, and normally high (with pullup resistor to 5V).
Can you fix that ? A resistor from 4k7 to 10k is fine, perhaps 22k is also okay, but use 10k if possible.
While you fix that, can you also add 100nF to 5V and GND, near the ATmega chip.
Can you check the reset button with a multimeter ? To see if you use the right pins.
Those buttons have the habit of rotating themselve 90 degrees while you are not looking.
That's it!
I build a pull-down system for the resetbutton.
The + and - line of the breadboard in the documentation was reversed from my board.
THanks for looking and answering.
I don't understand where the 100nF cap must be placed. Simply between 5V and GND at the Atmega?
Johan
jmnijsse:
I don't understand where the 100nF cap must be placed. Simply between 5V and GND at the Atmega?
Yes, it's that simple I always learned that the closer to the atmega, the better. Don't know if thats still being done but on a breadboard I always do it. The connections on a breadboard are not optimal.
A 'decoupling' capacitor it so reduce the noise by the ATmega chip itself on the 5V line.
Suppose the ATmega has a long wire to the 7805 regulator, and that wire is almost like an inductance. The ATmega chip running at 16MHz will cause high frequency noise on it's 5V line. That noise can be so bad, that the ATmega chip won't run properly anymore.
As C-F-K wrote, it is even more needed with a breadboard.
A simple 100nF to GND and 5V next to the ATmega chip, and that noise is gone.