I got my first Arduino a couple of years ago but it wasn’t until recently that I tried making a standalone circuit with just the microcontroller. It sounded intimidating to me before I tried it but now I look forward to seeing my projects break away from the Uno board. There are many resources out there that can help you do the same, but I wanted to throw in my vote of confidence and show you the method that has worked well for me so far.
Arduino Uno board
Yes, you’ll need one if you’re going to follow this tutorial. This tutorial is geared toward people who have already been playing with their Uno and want to shrink a project. The Uno will act as our programmer. You can program the chip directly using other methods but I can’t speak of them since I haven’t tried them.
There are other Atmega chips out there so make sure you’re using this one if you’re going to follow the information here. Also, get one with a bootloader already on it. I purchased mine from Dipmicro which has the Optiboot bootloader on it already. You can get the other one with the Duemilanove bootloader, but make sure to select “Arduino Duemilanove w/ ATmega328” when you program using the Arduino IDE.
You can’t have too many breadboards. I’m sure you already have one sitting beside you right now.
We’ll need two 22pF (22) and one 100nF (104) capacitors.
We’ll need one 16Mhz crystal oscillator.
We’ll need one 10Kohm resistor. We’re running the blink sketch so we’re going to need another resistor for the LED.
One LED for the blink sketch. A power indicating LED is optional. Just remember the current limiting resistor!
(Optional) Voltage Regulator
The Atmega328p chip can handle 5v only. If your power supply gives you more than that, you’ll need a regulator to drop it down to 5v. Check out my LM317 tutorial for one solution.
(Optional) Push Button
If you want a reset button, you’ll need a push button. I personally don’t include them because all of my projects have an on/off switch that I could just toggle.
Connecting the Circuit
You can find the pinout of the Atmega328 chip from the datasheet. The chips that I get already have a label. There are places that sell the labels if the chips that you get don’t have them already. They’re great to have because there’s no use for a schematic. It’s really that simple.
I don’t have a schematic to share but a quick search on Google will get you one. If you’re good at following text instructions, it’ll be easy:
1. RST has a 10Kohm resistor to 5v.
2. The 2 Vcc’s on both sides and REF go directly to 5v.
3. The 2 GND’s on both sides go directly to ground.
4. The 100nF capacitor connects Vcc and GND on the left side of the chip.
5. X1 and X2 go to ground using the 22pF capacitors.
6. The 16Mhz oscillator connects X1 and X2.
I don’t have any larger breadboards to show you how to connect it up, but this small breadboard is a great example of how small you can get the controller to be.
Like I said earlier, we use the Arduino Uno board to program. Just remove the current chip, insert the one you bought for your shrunken project, and program as you normally do. It’s a good idea to unplug the board when you’re swapping chips. Once you get comfortable, you won’t even have to prototype on the Arduino Uno. You’ll start using it just for programming. There are other ways to program the chip directly but I haven’t tried them (yet). This way just seems the easiest considering I already had the Uno so I won’t need to buy anything more.
So yeah… There are guides out there that may be better to follow with more graphics. Once you do it once, you’ll never go back to sharing around your Uno between your projects. I just wanted to show off my method and encourage people to try it!