Attiny Serial options?


i've tried searching but didn't really find a suitable answer. I'm inquiring as to what options do i have to send/recieve serial data between the PC and the Attiny with the least amount of (of the shelf) components and by USB?

I don't need to program the chip, just send/recieve data on the serial port.

I've looked into those AVR programmers on spark-fun, but i'm interested to hear any other options that might be available.


SoftwareSerial is the solution. there are a number of implementations of it out there - note that these all have some limitations (that's why they put hardware UARTs, doing it in software is not ideal).

Or use a tiny that has real serial (like the ones the core I wrote works with - the 1634 and 841 both have 2 serials, and the 4313 has 1)

In terms of hardware, you just need a USB<->serial (ttl) converter. You don't care about the pins so much if you're not using it to program something with a bootloader, but I'd try to get ones with the normal 6-pin pinout (gnd, cts (not used), vcc, tx*, rx* dtr), so I could use it to program if I later wanted to. There are a couple of different adapters FTDI, CH340G, etc - pick your poison - some of us dislike CH340G's because the drivers look super half-assed and they're made in china, while others hold a grudge against FTDI over the bad driver/counterfeit chip scandal. FTDI is the traditional preferred choice.
CH340G adapters with the wrong pinout on the header (the one that's Gnd Rx* Tx* 3v3 Vcc 5v) can be modified to work as programmers by cutting away the shrinkwrap to get to the DTR pin (pin 13) and running a wire out to the connector as well as Vcc (since vcc pin is used with the jumper to set voltage). This is actually what I prefer, since they're also very cheap ($1-2 vs $4-5 for FTDI, and, inexplicably, CH340g with correct header pinout). I also subscribe to the "screw ftdi" camp mentioned above (full disclosure)

*I might have TX and RX backwards there, but there aren't versions that are the same as the right-one but have tx/rx swapped.

You could also just buy the off the shelf Trinket (an attiny85 from Adafruit). The Trinket has a built-in USB for bootloading only. But can be made to use the USB for serial communication with a helper PC program. There is a "Fake USB" serial communication PC program you can use. See the tutorial, Overview | Trinket Fake USB Serial | Adafruit Learning System

Thank you both. Very informative. I'll look into each option to see what best suits my requirements.