Hi all, I have programmed an atmega 328p MCU on the nano board. The nano board is plugged into my solderless breadboard. There are a few other external components on the board. I could use as is to run the controlling circuit of my project. The main problem with this is the current requirements of the nano.
If I use the uno board I can remove the atmega 328 after programming it. Could I then plug it in to the breadboard? Would the pins fit? There are so many pins on the atmega making it difficult to insert without bending pins.
Then I would need to add a 5v source and crystals. Can anybody tell me what exactly I would have to include on the 328 to make it functional after having programmed it and removed it from the uno board. Apart from my external components of course. Thanks in advance.
If you've already programmed your chip then you don't need the part at the end to add the usb to serial connection. You only need that if you want to program it without pulling it out.
I would also highly recommend a ZIF socket. Look that up on google. There are lots of types. Just pick one that looks like it will fit your board. ZIF sockets have a little lever that locks and unlocks to allow the chip to just slip in so you don't bend pins.
Use aPro Mini instead. Remove the LEDs and voltage regulator for minimal current draw.
I build lots of stand alone boards with 328 DIP processors. I use the MiniCore core to bootload those chips. With the MiniCore core I can easily bootload for using the 8MHz internal clock so that there is no external crystal required. Only decoupling caps on Vcc and AVcc and a 10K resistor from reset to ground Vcc and you are good to go. The 328 at 8MHz will also run on 3.3V which is good if your project uses 3.3V sensors or other peripherals. Plus, with MiniCore at 8MHz you get 2 more GPIO pins.
The GitHub page has installation instructions.
Reset Circuit for 28-pin ATmega328P MCU (4.7k also woks well):
Why do you think that the Uno require a less current than the Nano? The boards has the same mcu - atmega328 - so it power consuming is quite similar
Does that same indicate "identical architecture"?
Not only an architecture, but the MCUs itself are the same in both boards
Oops! Brain fart. Fixed. Thanks.
I had a few of those last month 
+1 for using a Pro Mini clone. It's going to be smaller and cheaper than that honking big 328P DIP, plus it already has a crystal. You may find that disabling the power indicator LED will bring the current low enough for your needs.
The only downside is that the A4 and A5 pins, which are the I2C pins, are not breadboard compatible, so you would have to solder in a couple wires for them.
I have that zip socket you mention. I have also recently come across an IC insertion and extraction kit. I could program the atmega328p on the uno board and then extract it and insert it on my breadboard hopefully then without bending any pins.
It may only be necessary to extract it and then insert it in the ZIF socket which have pins on the other side corresponding to the sockets. This would then be pushed into the breadboard.
I was talking about the current requirements when the atmega328 is on the nano or uno board. This is 20ma. If I remove the 328 from the board(after programming) which I want to do the current draw will be much less. Sorry for the confusion. My fault I think.
the nano board does not have an extractable dip atmega 328p. But it does plug into a solderless breadboard. Good for testing your project.
The uno board has a dip 328 which can be programmed and then extracted from the board. The uno cannot be plugged directly into the breadboard but the 328 can be programmed with the same program already checked on the nano board.
Not quite the same b707. The uno board has a dip 328. the nano does not. You cannot extract the 328 from the nano for standalone operation. You could mass produce your programmed 328 by inserting new 328s into your uno board socket and programming using the uno programmer.
Now, your UNO Board is missing 328P MCU. What are you going to put in that empty 28-pin DIP socket? You must put there a 328P chip with a Bootloader Program. From where, are you going to get it or make it?
You don't necessarily need a chip with a bootloader, you can flash the bootloader later using a programmer.
You can buy 328P separately from the Arduino
If someone uses an Arduino UNO Board, then the UNO Board must have an ATmega328P MCU with the correct Bootloader/Fuse bits installed/set -- am I correct?
No
If you have an Uno without chip and Atmega328p without bootloader - you can first install chip in the board and than flash the bootloader and fuses.
The result will be the same as if you have a standard Uno