Standalone atmega - uplooading sketches with FTDI

Hello! Time came for me to put one of my Arduino projects to life. So I made a nice board in Eagle, and now I want a way to program the chip. I have ISP programmer, but I would rather use bootloader to upload my program (less wires).

So I will connect rx/tx of my chip to Arduino board and they will have common ground.

What I can't figure out what to do with reset button. Although I have it on my Arduino (Freeduino NKC) I never used it. Do I need to put on my standalone board? If it depends on bootloader version type - how do I figure out which one do I have/need.


The auto-reset / upload feature uses the DTR line which the standard FTDI cable doesn't bring out, so in order to upload sketches you'll need a reset switch on your board unless it has a 'wierd' bootloader which works another way. If you havn't got the FTDI cable yet, there is an option which does bring out the DTR line and is cheaper than an FTDI cable.

There are variations made by other companies.

The auto reset is easy to implement. Download the intructions for The RBBB, which is a minimalist circuit for the arduino which includes auto reset (and a reset switch) as well as giving good insights as to how the upload process works :

I want to use rx/tx lines from my Arduino board.

Can I use the auto-reset/reset function from my Arduino?
I mean I could just take the chip out of the Arduino and connect all the necessary lines to my standalone chip.

I already know I have to connect rx/tx/GND - what pin is the reset?


Yes, you can use the auto-reset circitry from your Arduino board. You first must remove the processor chip from you Arduino board, and then wire ground, TX, RX, and reset pins from the Arduino to your standalone board. The reset pin on your standalone board is pin 1 of the processor chip.


Read the instructions for the RBBB as I posted it explains it all in very easy terms. I thought swapping chips was an easy way to go, you rapidly get fed up if you're developing a sketch because of the time it takes to swap them. (Without mangling the pins and/or sockets) ;)

After building the breadboard arduino and looking for an effective way to be able to use that as a basis for programming many atmega chips easily, I thought this might be the way forward, I hope I can make a shield style drop in unit then I can use my existing arduino board without worrying about killing it or any chips or providing all the support components needed for the standalone, if that does't prove to be an effective solution I can just make a breadboard based unit for programming and a single cable and leave my arduino boards looking shiny and un-abused.

Thank you all for your help! I will probably not implement auto-reset on my board because I want to keep as simple as possible. The sketch is almost ready anyway, so I will make the board, connect everything, connect Arduino without the chip to my board, make some adjustments to the sketch, and then close the case :)