I'm having this strange error, which pops up around 90% of the time. I am trying to program my attiny25 using USBasp and the Arduino IDE / library. Sometimes it works, most times it doesn't.. This error occurs on large sketches as well as new sketches, with just the empty setup() and loop() functions. The error looks quite random to me, because my program just uploaded after trying around 10 times. Compiling goes fine. The error always occurs at byte 0x0000, and always in the format 0x00 != 0x _ _. I have six wires (correctly) connected from the USBasp to the attiny25. I do not use any resistors, capacitors etc.

Could anyone tell me what could possibly cause this error, and what to do to fix it?

3 Answers 3


The cause is most likely the fact that you "... do not use any resistors, capacitors etc."

Connect a 100nF capacitor between Vcc and GND. Connect a 10KΩ resistor between RESET and Vcc.

  • I have the same problem. As suggested, I have a 10k resistor between vcc and reset, and a 100nF capacitator between Vcc and ground. However, flashing is still extremely unreliable. Is there anything more I could try? Commented Jan 22, 2017 at 19:27

The problem has to do with the auto-reset feature, so you have to make sure the Reset pin is connected to VCC via a pull-up resistor. Generally, a 10k resistor will be just fine.

  • 10µF capacitor between GND and RESET may also work
    – PBahner
    Commented May 31, 2021 at 15:30

I had the same issue even with capacitor between Vcc and GND and resistor between RESET and Vcc. Finally, I use 5V Instead of 3.3V to power up my ATTINY and the problem was solved!

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