Using this method, you should be able to get sensor data from many sensors at once using only 2 pins on your Arduino. Assuming everything works, you are ready to go. It requests the data from the slave and then outputs it to the serial monitor.

I used a Mega, but you can use whatever you have. It reads one HC-SR04 sensor and acts as the I2C slave. You also need my TinyNewPing library installed.ģ) Now you have the libraries installed. This is important for stable I2C communication (consider making my ATtiny programming adapter!). You need to burn your ATtiny85/45 to 8MHz. Anyway, if you need more details on getting an ATtiny running see my previous posts linked above or click on the ATtiny label. A recent update allows ATtiny support with Arduino 1.5. Now however I prefer the Google Code core. In the past I have used the core from High-Low Tech. You will also need the ATtiny core for whatever Arduino IDE you are using. Find his library HERE (download zip link is in the bottom right corner). He added a bit more functionality including an onRequest and an onReceive function (which I use in my examples). I have used the Master library from it, but for the Slave library I will be using a fork by Rambo. The original library by BroHogan can be downloaded HERE. However, thanks to some great work by Arduino users BroHogan and Rambo we do have the TinyWire library. The regular Wire library will not work on the ATtiny side.

For this you have a few options, but I will only be using one of them. In fact, I even transmitted data from my PING sensor! Check it out HERE.ġ) First off, we need an I2C library for your ATtiny. I have also done a post on I2C communication. It also discusses running the NewPing library on an ATtiny (my modified TinyNewPing library). If you have not already done so, check out my previous post on a serial sonar sensor. Together these two parts can save you money while increasing functionality over premade solutions. Both the sensor and the microcontroller can be found online for a few dollars. This will be accomplished by making an I2C controller for an HC-SR04 sensor out of an ATtiny85 (or ATtiny45). In this post I will show you how to cheaply make an I2C sonar sensor for your Arduino.

Wire library for attiny85