I know this problem is kinda common but I had to post it anyway.

Before anything, I would like to inform you guys that I changed the fuse of my Arduino Pro 3v3 @ 8MHz to allow 1.8 V brownout and also programmed CKDIV8 AND CLKOUT. In other words, the fuse configuration is this: E:FE, H:DA, L:3F.

The programmer is the Arduino 2009 running as ISP programmer. The target is Arduino Pro Mini 3V3 @ 8Mhz.

I also used a 0.1uF cap between reset and ground in the Arduino programmer.

After a good time using the Arduino Pro without problems, some random problems began to appear when I tried to upload a program with the programmer (Arduino as ISP). So I tried to burn the bootloader again and the following message appeared ""avrdude: Yikes! Invalid device signature."

The same occurs when I try to communicate with avrdude using this command "avrdude -c arduino -p m328p -P COM3 -b 19200 -v".

Some tests I did:

  • Continuity test directly at uC pins between those signals: SCK, MISO, MOSI, (/SS - /RESET). No problem good connection.

  • Verified the clock in XTAL1 and XTAL2. No problem 8MHz.

  • Verified the clock in CKOUT (Arduino Pro pin 2) and measured 1MHz.

  • I also tried to delay the avrdude using -B5, B10 and another values. With a quick search on Google some people are saying that those delays don't work with the Arduino as ISP.

  • I used some sketches for slow clocks, which I don't remember, and no luck.

  • External power and no luck again.

What am I missing? Do I need to change something to communicate with Arduino Pro running at 1MHz?

1 Answer 1


If you are burning the bootloader through the IDE it won't expect the CKDIV8 fuse to be set.

I have a bootloader programmer which you could use to reprogram the bootloader. You just need another Arduino (eg. Uno, Mega) and connect 6 wires between each of them like this:

Program bootloader

The sketch for programming the bootloader is available on Github:


You want the one in the "Atmega_Board_Programmer" subdirectory.

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