ATtiny84 usb interface help.

Thread Starter


Joined Sep 4, 2017
I am trying to build a small development board with the ATtiny84, but I am having trouble figuring out how to wire USB into it. The only material I can find on it suggest that I need to buck the input down to around 3.6v but this doesn't make sense because the ATtiny84 is rated for 1.8v-5.5v. Any input on this would be appreciated and a schematic would be even better.

thanks Paul


Joined Feb 24, 2006
Where are you getting your USB information. AFAIK it works on +5VDC and GND for both the power bare and the data pair. I didn't know the ATtiny84 had a USB interface inside.


Joined Feb 24, 2006
Why do you suppose the guy who wrote: "(which apparently have to be 3v3?)" put a question mark after 3v3? It was because he did not know what he was talking about. AFAIK USB works on 5 Volts. Without dedicated hardware inside the ATtiny85 are you planning to bit bang the USB at 12 MHz. or 480 MHz.

The authoritative source on all this is the USB specification, available as a free download from You might have to spend some coin for the latest and greatest but the 2.0 spec has been free for quite some time.


Joined Apr 11, 2010
Yes I have but I would prefer not to use an Arduino. If at all possible.
You need a programmer to upload code to the ATTiny. That’s all the Arduino is used for. If you don’t want to touch an Arduino for fear of catching something;), you’ll have to buy a commercial programmer. Sparkfun offers one for ~$20..