Monday, July 9, 2018

Sensor framework for Data Logging

This is simple sensor kit to drive 8 active or passive sensors and log it's data into remote Android application. This system also have an option to activate external device(s) based on specified threshold of sensor data.

This sensor controller is mainly build around Raspberry Pi Model 3 B+ and PIC16F877A MCU. PIC16F877A MCU is used to interface/select sensors and it's built-in 10bit multi channel ADC is used to capture the analog signals from sensors.


During the prototype stage following sensors are tested with this system:

  • LM35 precision temperature sensor
  • MQ7 Carbon Monoxide gas sensor
  • Electret Microphone
  • NSL-19M51 LDR
  • HC-SR501 PIR sensor
  • A3144 Hall effect sensor

Apart from above list this system can use to drive and capture most of the other analog/digital sensor signals such as current sensors, pressure sensors, chemical sensors, humidity sensors, etc.

In this system Android monitoring application is designed to connect with the sensor platform through a network link (such as using Wi-Fi or mobile data network) and it can also control this sensor platform via this link.

This given version of Raspberry Pi server is designed to handle only one client and it can be easily extend to multipal client support by modifying the communication protocol of Node.js application and Android application. We build this system entirely for demo purposes and we didn't get a chance to extend it to multi-client support.

Android control and monitoring application.

The trigger system of this system is based on MOC3041 optocoupler and BT138 TRIAC. At prototyping stage we use this system to drive 5W - 230V incandescent light bulb. Because of high current rating of BT138, this system can use to drive AC equipment(s) up to 10Amps.

All the schematics and source codes of this project are available to clone at https://github.com/dilshan/android-datalogger.
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