Using Arduino Uno to program ATTiny85-20pu without capacitor.


Is it possible to program the ATTIny85-20pu without a capacitor using Arduino? I have tried to follow aton of tutorials on YouTube, but none of them work.

Keep getting the:

“the selected serial port avrdude: stk500_disable(): unknown response=0x12
does not exist or your board is not connected”

Error, after uploading code.

I have uploaded the ArduinoISP code, and changed the Board, processor and programmer settings, but I can’t get it to work.


Unsure which capacitor you refer to. Two are needed

  • A capacitor (typically 10uF, though anything higher than 1uF will work) between reset and ground on the Arduino running Arduino as ISP to keep it from resetting when the serial adapter brings DTR low as the serial port is opened. Exact value is not critical; this can easily be a "pull" from discarded electronics.

  • A 0.1uF ceramic capacitor between Vcc and Ground on the ATTiny85, with the length of wires/leads minimized. This is required for reliable operation - I have had problems programming attiny85 parts when it was not properly connected (this resulted in me having to throw away one of the first batches of PCBs I had made).

So a the reset and ground capacitor is 100% needed to upload the code?

AFAIK you may simply short 5V and Arduino's reset pin with a jumper wire (or a small resistor).