What’s the most esoteric I2C sensor that you can imagine? (And is it really the case that we haven’t seen an I2C slave device hack since 2010?) But if you’re building your own devices, the sky is the limit. But what do you do when you want to make the I2C device? ’s project makes use of TinyWireS, a slave-mode SPI and I2C library for AVR ATtiny Arduino projects.

Everyone and their mom uses I2C to connect to sensors, for which the Arduino “Wire” library or “i2c-tools” on the Pi do just fine. We’re covering this because we rarely see people coding for I2C slave devices. It’s all up on GitHub if you’re interested. wired up a tremendously simple circuit, downloaded some I2C slave-mode code, and added an LED for good measure. You can, of course, buy I2C ADC chips and modules, but when you’ve already got a microcontroller that has ADC peripherals on board, why bother? He wanted to include a light sensor but the problem is, the Pi doesn’t have a built-in ADC to read the voltage off the light-dependent resistor that he (presumably) had in his junk box. Has a weather station, and its nerve-center is a Raspberry Pi.

Arduino wire library for raspberry pi