Fine dust accounts for a fairly great part of the recent environmental issues. According to the Korea Environment Corporation, the number of times of the warning for the ultra-fine particle was 86 times as of last year. This is 1-2 times a week, which is not a small number of times. As a result, each local government is providing a service to inform the local residents by installing an electronic board to check the values of fine dust and the ultra-fine particle. However, the installation of the additional electric board to measure fine dust needs to be considered the place and cost. Also, there is a disadvantage that the line cost is expensive when we consider the size of the data.
This article shows that SKT LoRa and the traffic electronic board will be used to prototype the concept representing a traffic sign and the value of fine dust.
STEP 1. Project Outline
In order to use LoRa technology provided by SKT, we must use ThingPlug which is SKT Platform. That LoRa device sends data to ThingPlug is called Uplink. That the server sends data to LoRa device is called Downlink. LoRa device periodically outputs the date of fine dust to LCD and uplinks the data using ThingPlug. LoRa device also use moving average to calibrate the data when measuring fine dust. When receiving a Downlink from the server, it recognizes the Downlink using an interrupt and outputs the corresponding traffic sign.
STEP 2. Preparation before Starting Project
2-1. W5100S-EVB (Detail and Buy)
2-2. LoRa Kit – LoRa EVB + Solu M(Supporting SKT Module)
2-3. mbed online complier(link)
2-4. Fine Dust Sensor – Sharp GP2Y1010AUOF
2-5. LCD – JUTF43
2-6. IoT Platform – ThingPlug
STEP 3. Hardware Connection
WizWiki-W7500, LoRa module, and LCD provide UART connectivity. The fine dust sensor requires 1 digital pin and 1 analog pin and connects to VCC and GND, respectively.
The hardware connection is as follows. In the case of LoRa module and find dust sensor, the power is supplied from WizWiKi-W7500. In the case of JUTF43 LCD, the power is supplied from Micro USB.
If the hardware connection is completed, we can use online compiler provided by ARM mbed to write the firmware to WizWiKi-W7500. The firmware source can be imported into Online Compiler at the following link.
After importing, you can see that it is saved as binary file after clicking Compile as follows.
You can write the downloaded binary file to WizWiKi-W7500 by referring to the following link.
STEP 4. Explanation of Source Code Link and Major Code
Because using LoRa module is a connected serial to the module and transmits AT command of the module company, I will mainly explain how to use the fine dust sensor and calibrate it.
4-1 Sensing the Value of Fine Dust
The fine dust sensor is an analog sensor and measures the value by considering sampling timing according to the sensor specification.
4-2 The Value of Fine Dust Calibration
The following functions are used to calibrate the value of fine dust and return by calculating the average in a FIFO structure.
4-3 Extracting the Value of Fine Dust
Calibrates the measured analog value, changes it to a digital value, and converts it to the value of fine dust.
All sources can be downloaded at the following links. You need to add JUTF43 library in order to use LCD.
Library Link: https://os.mbed.com/components/JUTF43/
Source Link: https://github.com/stkim92/Curation-Is-Creation
STEP 5. <Project Completion Result>
We could transmit the value of fine dust to IoT platform (ThingPlug) and output the value on LCD by the data received from the IoT platform using SKT LoRa technology. I was able to experience the new technology and IoT project and hope that readers have come up with an idea for additional projects.