Its time to shrinkify your projects.
Many things can be powered by ATtiny85. Also it is basically every where, from alarm clocks to microwave ovens, washing machines and even phones!
Comparing ATtiny85 to an Arduino
Arduino boards are more easily manipulated to prototype pretty much anything but sometimes you have to go for something more discreet and cheap, that’s where ATtiny85 comes to play, its much smaller cheaper but as versatile as and Arduino.
As mentioned above despite its small size the ATtiny85 is a powerhouse of components and peripherals. Below we are going to take a little trip to the things that make ATtiny85 a great companion.
Operating Voltage (2.7v – 5.5v)
ATtiny85 can easily operated with as little as 2.7v, this means you can attach a 3v coin cell battery or a LiPo battery and also with a USB.
Power
Using the ATtiny85 with 5v or a USB and running at 1 MHz, it will consume less than 2mA, but if you need it to have less power consummation you can use Watchdog Timer along with sleep. Using Watchdog mode ATtiny85 consumes less than 5 μA while sleeping. So with this info theoretically you can power it from a coin cell battery for over half a decade!
You can follow this Watchdog tutorial from Technoblogy.
World Communication
The ATtiny85 can interface with the world using it’s 5 integrated pins. We have to thank ATtiny85’s Universal Serial Interface (USI).
USI allows the ATtiny to communicate with I2C and SPI protocols. Pretty much every digital component uses this 2 protocols to communicate with a micro-controller.
Programming ATtiny85
The lack of a USB connector its what keeps the ATtiny that small. But there is nothing to fear, probably you have somewhere an Arduino Uno, nano along with other Arduino compatible boards that you can hook up to ATttiny85 and using the ISP connection you can program it.
You can follow up this tutorial to have an introduction with ISP programming.
ATtiny85 is to small for you?
If ATtiny85 5 IO pins are not enough for you, you can use ATtiny84 which doubles the IO pins without making the whole thing too much bigger. All things mention above are almost identical to ATtiny85. ATtiny84 is not the only one you can search the web to find what fits you better.
Disadvantages
The main disadvantage using ATtiny85 its hard to debug it. It lacks the ability to output information to the Serial Port just like an Arduino which means it’s difficult to see what the sketch is doing. Also ATtiny85 has a few kB of usable memory so you must be careful not to waste space.