The ambient light sensor
To get started with our night-light project, we'll start by wiring up our TSL2561 I2C light sensor and making sure we get good data reads by having it print out to the command line.
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Wiring up the sensor
In order to wire up our light sensor, we'll need to know which are the SDA and SCL pins of the Pi. For the Pi 3 and 3 B+, SDA is P1-P3 and SCL is P1-P5; these are also usually labelled on the cobblers as SDA and SCL. In order to get the sensor working, we'll need the power pin; this sensor is not 5V tolerant, so we'll need to use a 3.3V power pin. We can attach GND on the sensor to any ground pin.
The SDA and SCL pins on the sensor need to be connected to the SDA and SCL pins on the Pi, respectively. In the end, your light sensor should be wired up like the following diagram:
Now that we've wired up our sensor, it's time to figure out how to print that data using Johnny-Five and other Node.js modules so we can make sure it's up and running.
