I recently bought a Pro Mini and an Uno. I was wondering - as far as I know, the Uno cannot yet be used as an ISP (judging by the pinned post on the bootloader, it sounds like they're making progress with it though!). Is there any way to use the Pro Mini as a bootloader?
However, if your Uno was "recently" purchased or if you have updated the bootloader, it is not necessary to disable auto-reset. If you are using Arduino IDE 1.0 then the stock ArduinoISP sketch does not work; report back if you are using 1.0 and need help.
Yeah I'm currently working on 1.0, but I did read one of the posts here that said using 0023 was successful. Was going to PM you regarding your version of the sketch though.
I have heard problems with version 1.0 and Arduino ISP. I am not sure if this is true or not but if it doesn't work, you should try downgrading your Arduino IDE.
If you are using the Arduino-1.0 IDE to load the ArduinoISP sketch you will have a problem.
Geta copy of Arduino-0.22 and load the ArduinoISP sketch and then the Arduino board will work just fine.
If you are using AVRDude to transfer a HEX file, the Arduino-0.22 sketch will run at -b 19200, the Arduino-1.0 sketch will run at -b 9600. If you are not running AVRDude directly this won't mean a thing to you.
I didn't disable the reset, as per your instruction that a recent Uno wouldn't need it to be disable, which is consistent with what I read online, but I'll try that next w/ a 10k resistor. (Btw I'm using the bare minimum circuitry, trying to use the AVR's on-board 8 MHz clock. Is this not right?)
Hi kf2qd,
Thanks for the thought. I was using 0023, but I'll try 0022 next.
I set up the breadboard with the external oscillator, then used 0022 to bootload. Once that worked, I tested with a simple sketch from 1.0, and it worked!
Please let me know if there's anything that might go wrong with that approach, but in the meantime thanks to all!
GoForSmoke:
I was using a 10uf cap between reset and grnd. It worked when I programmed a Tiny85 but is the resistor method better?
The best method is one that requires neither the capacitor nor the resistor. For example, I have an Uno R2 with the latest version of optiboot installed that does not require disabling auto-reset.
I have no idea if the capacitor or resistor is better in any way.
Coding Badly is correct. I often use an Uno R3 with optiboot to load bootloaders on breadboard or custom designs, it works quite well and doesnt need modification like the older bootloader needed. Here is a video how to showing burning the bootloader on with an Uno, ArduinoISP and IDE ver 22. Saw a few of these threads and decided to make a short vid to see if it helps anyone. HowToBootloadAtmega.mov - YouTube
the latest version of optiboot ... does not require disabling auto-reset.
Is anyone doing this on Mac/linux with bare avrdude and ftdi based "Uno" boards?
I know it's supposed to work, but on my Mac I keep getting failures that look like autoreset is still preventing it from working, though it gets surprisingly far (and works OK WITH some form of auto-reset disable):
It looks to me like ArduinoISP has a bug or the toolset did not build it correctly. If you don't mind, please try the TinyISP.ino I sent; let me know if you need another copy.