I'm trying to program an Arduino Pro Micro with another Arduino Pro Micro. The purpose is to verify that I can use this Pro Micro board reliably as an ISP to program another Arduino device that does not have a USB interface.

These are actually Pro Micro clones but they seem to work quite well using the Arduino Leonardo profile. I'm following this pinout.

Here is the photo of the setup:

enter image description here

The "red" Pro Micro is set up as ISP using the stock ArduinoISP sketch (didn't think anything needed changing). The "white" Pro Micro is the one I'm trying to program.

The pins are connected, 5V - 5V, GND - GND, MISO - MISO, MOSI - MOSI, SCLK - SCLK, Pin 10 - Pin 10 (reset? this might be wrong).

I've confirmed the ISP sketch is running by the green heartbeat LED. The three LEDs on the red board are connected to pins 7 (top), 8, 9 (bottom), with 9 being the heartbeat.

I loaded the Blink sketch and changed the LED pin to pin 9 since the default pin 14 on the white board is being used as the MISO pin for programming.

In the IDE, I set the board to Arduino Leonardo, port to the red board's port, programmer to "Arduino as ISP" and ran "Upload Using Programmer".

The only output I get is:

avrdude: Yikes!  Invalid device signature.
         Double check connections and try again, or use -F to override
         this check.

Since I'm really just beginning all of this, I'm a bit confused what might be wrong and what could be a next troubleshooting step. Any help appreciated.

  • 1
    "Pin 10 - Pin 10 (reset? this might be wrong)." yepp, should be Pin 10 - RST (on target). Commented Feb 27, 2016 at 23:27

1 Answer 1


As Mikael Patel notes, pin 10 on the programmer Pro Micro should run to RST on the target.

That might or might not fix the problem. In some previous instances of the “Yikes! Invalid device signature” [1,2] bad breadboard connections turned out to be the problem. I suggest you run a second (or even a third) set of jumpers in parallel with the first set. Of course use matching colors to avoid confusion.

  • I've done that to no avail. Doesn't seem to make a difference.
    – Ana
    Commented Feb 28, 2016 at 20:31

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