Attiny85 as USB-to-Serial

Using Arduino Microcontrollers
#1

Hi,

today I found this page: paperduino.eu . The idea to make an Arduino on paper is old,
but what i found really interesting was the Attiny85 bootloader, so you can directly put USB on the Attiny. (GitHub - micronucleus/micronucleus: ATTiny usb bootloader with a strong emphasis on bootloader compactness.).
So i have 2 questions:

  1. is it possible to take an attiny85 with this bootloader to make an USB-2-Serial Adapter for normal Arduino projects?
  2. When it is possible to let the Attiny directly communicate with USB, why isnt there a solution for Atmega328?

Regards,
Bauerbyter

(P.S Sorry for my bad english)

#2

I suspect that bootloader is intended to be used with a USB-TTL device such as an FTDI cable.

To make the Attiny into a USB-TTL adapter you would need to write a program that can handle raw USB I/O. That is a complex process and my guess is that if you know how to do it you would not have to ask a question here.

...R

#3

bauerbyter:

  1. is it possible to take an attiny85 with this bootloader to make an USB-2-Serial Adapter for normal Arduino projects?

Yes, but don't do it. This forum has about 10000000000000000 posts from people failing to get software serial working on Tiny85.

USB-to-serial costs $6: ftdi basic breakout: Search Result | eBay

#4

ok thanks, i thought it would be fun to unterstand how this works, but when you say its to hard... i believe you!

#5

Robin2:
To make the Attiny into a USB-TTL adapter you would need to write a program that can handle raw USB I/O. That is a complex process and my guess is that if you know how to do it you would not have to ask a question here.

V-USB has that as an example sketch.

But before you do it: Go to google and search for “tiny85 software serial”. Count how many results say “it works!” and how many say “it doesn’t work!”

#6

As far as I know V-USB and software serial are two completely different things. I believe V-USB is code that allows a microprocessor to connect directly to a USB system - the same role that the FTDI chip does in an FTDI cable.

Software serial, on the other hand is code that allows a microprocessor to behave like a USART and send and receive data in the same way that the old PC serial ports used to do.

Normally you would use Software serial to allow a microprocessor to connect to a PC via an FTDI cable or equivalent - in other words you need BOTH.

It is by no means impossible to send or receive serial data with an Attiny provided you keep to a sensible baud rate. I wrote some code that works at 2400 baud on an Attiny45 running at 1MHz.

...R

#7

fungus:
USB-to-serial costs $6: ftdi basic breakout: Search Result | eBay

That is, if you buy the expensive ones, or are in a hurry.

#8