The role of this device is remote measurement environment parameters. It could be accessed anywhere where access to the internet is possible. It uses 6LoWPAN because it's modern IoT technology and have big capability. It is satisfying to create own device which uses ipv6 and Bluetooth.
Illustration 1: Block diagram
This block diagram presents general concept. It measures humidity and temperature using SHTC1 sensor. It connects to nRF51 DK using I2C interface. Second sensor is MPL115A2 which measures pressure. They are both connected to the same bus beacuse they have a different address. nRF51 implements coap-server to share measured data. This station is a powered by battery which allows
for easy placement of the device on the outside. It connects over Bluetooth Smart with PC.
When connection is established anyone can read sensors’ values by using CoAP application protocol.
Illustration below presents sensors’ endpoints, which can be read, using Cooper plugin for firefox.
Illustration 2: Copper plugin
It's not all. I have written application in C language where I have used libcoap 4.1.1 – CoAP Client. It accumulates data and insert to MySQL database. Enquiries are making with frequency stored in database and fully configurable from Web Application. Apache server has been installed on Debian.
It provides Web interface to present accumulated data with nice jQuery animation.
Pictures below presents this interface.
Illustration 3
Illustration 3 presents main page that shows last captured data.
Illustration 4
Illustration 4 presents temperature chart. Number of presentented samples can be change run-time. On x-axis it presents time that can be also configuirable. When user enters date or uses simple calendar widget and click Show button, page draws n samples before this date. The same chart is drawn for pressure and humidity. Subpage „Settings” allows to change sample period in seconds.
Illustration 5: Station inside
Illustration 5 shows nRF51 DK and custom board which includes sensors. All element were mounted in easy to set up case.
Illustration 6: Closed station box
The project took a part in the Nordic’s IoT Contest in Krakow in Poland. You can see more on the official website: http://nordicsemi.eestec.pl
