Build a Raspberry Pi Temperature Logger with a $5 I2C Sensor

Follow these concise steps to turn a $5 I2C temperature sensor into a reliable data logger on a Raspberry Pi. The recorded values are written to the SD card, making them ready for Excel or any data‑analysis tool.

Components

• Raspberry Pi (any model with GPIO)
• SF‑SEN‑09418 I2C temperature sensor ($5)
• Solderless breadboard
• Hook‑up wires (male‑to‑female or female‑to‑female as needed)

Note: The Zagros Raspberry Pi starter kit contains everything except the sensor.

Step 1: Wire the Temperature Sensor

Connect the sensor to the Pi’s GPIO pins as shown. The ADD0 pin set to GND gives the sensor a unique I2C address (0x48). More than one sensor can share the bus as long as each has a distinct address.

Safety note: Do not power the sensor with +5 V; this will permanently damage it.

Step 2: Enable the I2C Bus

By default the Pi disables the I2C interface. Edit the blacklist file:

sudo nano /etc/modprobe.d/raspi-blacklist.conf

Change the content from:
# blacklist spi and i2c by default (many users don’t need them)
blacklist spi-bcm2708
blacklist i2c-bcm2708

to:
# blacklist spi and i2c by default (many users don’t need them)
blacklist spi-bcm2708
#blacklist i2c-bcm2708

Step 3: Load the I2C Module at Boot

Add the module to /etc/modules so it loads automatically:

sudo nano /etc/modules

Append the line:

i2c-dev

Step 4: Install I2C Utilities

Install the necessary tools and Python bindings:

sudo apt update && sudo apt install -y i2c-tools python3-smbus

Verify the sensor appears on the bus:

i2cdetect -y 1 – you should see a device at address 0x48.

With the I2C stack ready, you can now run a Python script (not included here) that reads the temperature and appends it to a CSV file on the SD card. The CSV can be opened directly in Excel for analysis.