How do you program your standalone arduino chip?

I have had this question as you did. Here’s two simple and cheap ways to program your standalone arduino chip:

1. You can program it with an arduino board: remove the ATMEGA328 processor from your arduino board, connect the TX, RX, 5V and GND to your homebrew/standalone, and upload as a regular arduino board. That’s what I’ve been doing for at least a good part of a month before I told my cheap self go get a USB TTL board.

Here is a picture. In the picture, the blue and green are TX and RX that I connect to the standalone. The black and red are GND and 5V from the arduino main board. Notice I didn’t connect the 5V because I already have a battery on the standalone so only GND is needed. Also notice that the ATMEGA chip on the arduino is removed (it’s in the greenish standalone now). Just go to arduino IDE and hit upload!

2. The second way: you can also remove the processor from the stand alone and plug into arduino to program it, pop it off and put it back into standalone. A zif (zero-insertion-force) DIP socket may help. Here’s where to get one:

Sparkfun

You may need to exert a lot of force to push this sucker into the arduino mainboard. Good thing is you have enough clearance to do so.

Here is a picture: