Team:UFRGS Brazil/Monitoring

Electronic System

We aim to build a monitoring system so the user gets to know when the temperature or pH on the filter is not appropriate to the bacteria by receiving a text message on his cellphone. We did it interfacing with Arduino.

Procedure

1. GETTING DATA

Our monitoring system is based in two sensors:

DS18B20: waterproof temperature sensor

Ph-1415: pH sensor

We programmed the Arduino to send a text message when pH is lower/equal to 5 or higher/equal to 9 and the temperature is higher or equal to 40ยบC.

2.SENDING DATA

Our alert reaction is based in one shield:

Arduino shield GSM/GPRS SIM900. It can send SMS and provide phone calls and do many stuff. When the pH or temperature hits those values, Arduino orders a request to GSM SIM900 to send an SMS with a predefined text to a predefined number. This shield requires external power supply so it can be initialized, we used a 2A supply. The SIM card used must be unblocked. It functions based on AT commands and it communicates to Arduino through RX/TX or 7 and 8 digital ports (but the programmer has to set it on the code).

This illustration is an approximation of our real circuit. In the real one we used a waterproof temperature sensor and a 4.7k ohm pullup resistor. This resistor is essential to the Arduino shield can recognize the DS18B20 and read its data.

It is important to mention that the calibration of the pH sensor is sometimes difficult and we described it here.

You can check the code here here