In this project am gonna explain about how to monitor the humidity, temperature and soil moisture level of the agriculture land using Intel Edison board. Here I have used DHT11 humidity/temperature sensor and soil moisture sensor.
The filed data goes to cloud using gsm modem( sim900a) and displayed using thingspeak API to display the data in graphical format.
Step 1: Required Materials
Intel Edison board
DHT11 humidity/temperature sensor
Soil moisture sensor
12v 1A adapter
Step 2: Interface Method
DHT11 sensor has 4 pins in their module such as vcc, gnd, data and NC. we need pull up the data pin with vcc through 4.7k resistor.
Its working on single wire protocol which send the commands and data through single pin.Data format is 8bit integral RH data + 8bit decimal RH data + 8bit integral T data +8bit decimal T data + 8bit check sum. If the data transmission is right, the checksum should be the last 8bit of 8bit integral RH data + 8bit decimal RH data + 8bit integral T data + 8bit decimal T data.
For DHT11 sensor we need to download Arduino library file to use this sensor. The library has test program to test dht11 and connect the data pin of the dht11 to Digital pin(9) of the intel Edison Arduino expansion board.
The soil moisture sensor has 3 pins such as vcc, ground, analogout. The analog out pin is connected to analog port pin(A0) of the intel Edison Arduino expansion board.
The data transfer module sim900a has 3 pins for communicating with microcontroller namely tx, rx, ground. The tx pin is connected to rx pin of the Edison and rx pin is connected to tx pin of the Edison.gnd is connected to gnd of the Edison
Step 3: POWER SUPPLY
DHT11 –3.3 – 5.5v
Soil Moisture - 3.3-5V
Sim900a – 12v 1-2A
Note: short all the ground pins
Step 4: WORKING
We need to give 2sec settling time delay for dht11, otherwise it will give wrong data due
to clocking problem. Because its working on single wire protocol.
As per the protocol says we can get humidity data and temperature data from dht11. The soil moisture sensor provide raw analog data of the soil moisture. We can see these values by serial print.
Then initiate the gsm modem for data transfer by AT commands. Connection procedure
1.Check the modem response
2. register on network
3.change to gprs mode
4.open the TCP channel
5. HTTP request to thingspeak server
6.send the data
7.close the TCP channel
Then open the thingspeak channel and display the field data in graphical format
DHT11 Arduino library : https://github.com/adafruit/DHT-sensor-library
Dht11 datasheet: www.micropik.com › PDF › dht11
Sim900a AT commands : www.propox.com › docs › SIM900_AT