DIY Arduino problem

That would be a good suspect.
You should also have the Vcc pin connected to the AVcc pin, and a 0.1uF (100nF) on both of those pins going to ground.

why is it needed ?

I did connected the Vcc to AVcc..Just that I do not put a 100nF cap in between the Vcc and GND ><

The 100nF caps help provide power stability.

The 22pF caps allow the crystal to function.

What will happen if I did not put the 100nF cap and 22pF cap ?

Thank you

Bit more noise. For a real example: http://content.screencast.com/users/erwinried/folders/Jing/media/32aee3d7-e4c4-43ff-9615-4cc574a24999/2012-07-07_1524.png compare blue with red, first I didn't want to add a cap to the power, microprocessor rebooted itself randombly sometimes.

The regulator was to remove the spikes :smiley:

Ok, I face that problem too..Hahaha..reboot sometimes. Then what is the importance of the 22pF cap ?

Vincent19:
Ok, I face that problem too..Hahaha..reboot sometimes. Then what is the importance of the 22pF cap ?

The same, it is one of the properties of a cap, but for the oscilator. In my tests, not that important compared to the cap in the power.

So, the minimum circuit for an arduino based development board is a 16MHz crystal and the 100nF cap for power supply and pull up resistor for RESET pin ?

Vincent19:
So, the minimum circuit for an arduino based development board is a 16MHz crystal and the 100nF cap for power supply and pull up resistor for RESET pin ?

No, you can use the internal oscilator (there is a fuse). And the reset is not required. The minimum is just the cap for the supply

The minimum is just the cap for power supply ? Then how can I use the internal oscillator ? What setting should I change ?

As I said it is a fuse, but you have to google for instructions how to set it, what value to use, etc I don't remember those.

eried:

Vincent19:
So, the minimum circuit for an arduino based development board is a 16MHz crystal and the 100nF cap for power supply and pull up resistor for RESET pin ?

No, you can use the internal oscilator (there is a fuse). And the reset is not required. The minimum is just the cap for the supply
[/quoteWhy the reset is not required ? Thought it needs to be pulled high for normal operation ?]

Vincent19:
The minimum is just the cap for power supply ? Then how can I use the internal oscillator ? What setting should I change ?

For avoiding the crystal, you should program the atmega as 8Mhz internal oscilator. Select arduino pro mino 8Mhz in arduino IDE as target board in order to obtain the right times.

Promini uses external 8 MHz oscillator, not internal.

learn how to use fuses:

http://www.engbedded.com/fusecalc/

The 22pF caps on the crystal are important as they help crystal to oscillate on its fundamental frequency..

eried:

Vincent19:
So, the minimum circuit for an arduino based development board is a 16MHz crystal and the 100nF cap for power supply and pull up resistor for RESET pin ?

No, you can use the internal oscilator (there is a fuse). And the reset is not required. The minimum is just the cap for the supply

Why reset is not required ? I thought RESET should be pulled up for normal usage ?

Thanks :smiley:

Reset pullup needed for most stable operation, see Section 3

You are free to chase noise issue, odd resets, etc. if you so choose.

AtmelAVR042 AVR Design Considerations.pdf (236 KB)

Yea, so I neeed a pull up resistor :smiley:

Thanks ^^