I created this system because we had an issue with our HVAC unit in our Data Center.
Hardware: Arduino YUN REV2, Gikfun DS18B20 Temperature Sensors, 2 LEDs, 2 220ohm Resistors, and 1 4.7Kohm resistor.
steps: start getting familiar with your YUN. The Arduino YUN comes with 2 Interfaces. the Linux interface and the Arduino interface. Connect your YUN to your PC and access the web interface.
A lot of the YUN functions can be modified through the IDE and the YUN web interface. Set up your wifi connection/ethernet and your root credentials and memorize your YUN localhost then access the Linux realm through ssh. I used Putty to do that.
If you are planning to use gmail to send your ssmtp notifications then you need to create a gmail account, enable 2 factor authentication, and create an app password
After you ssh-ed to the device you need to install the ssmtp package through command line
$opkg update
$opkg install ssmtp
---now modify your ssmtp configuration file by using vi---
$vi /etc/ssmtp/ssmtp.conf
root=[email protected]
mailhub=smtp.gmail.com:587
rewriteDomain=
hostname=” your YUN IP”
UseSTARTTLS=YES
AuthUser= [email protected]
AuthPass=GmailAppPassword
FromLineOverride=YES
Save your vi file
create a text file as a place holder for the code in the root directory and name it email.txt
I provided the code for this project 😊 have a blast with it
I provided a picture for wiring the sensor. I also used 2 LEDs to notify me when the temperature is over the previously set threshold and when the YUN is sending the ssmtp email