Smart irrigation systems tailor watering schedules and run times automatically to meet specific landscape needs. These controllers significantly improve outdoor water use efficiencies.
Smart irrigation systems tailor watering schedules and run times automatically to meet specific landscape needs. These controllers significantly improve outdoor water use efficiencies.
Smart irrigation systems tailor watering schedules and run times automatically to meet specific landscape needs. These controllers significantly improve outdoor water use efficiencies.
Unlike traditional irrigation controllers that operate on a preset programmed schedule and timers, smart irrigation controllers monitor weather, soil conditions, evaporation and plant water use to automatically adjust the watering schedule to actual conditions of the site.
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Digital Temperature Sensor Circuit
Temperature sensors are widely used in electronic equipment to display the temperature. You can see the digital clock displaying the room temperature value. It is due to the temperature sensor embedded in it. In this project, I will show you how to design a Digital Temperature Sensor Circuit. In the process, I will explain two circuits: one using 8051 Microcontroller and the other using ATmega8 Microcontroller.
The temperature value is analog. Hence, it is converted to digital value using an Analog-to-Digital Converter (ADC) and then it is displayed. This article describes the same, converting analog value to a digital value.
The main principle of this circuit is to take the analog temperature values, convert them into digital values and display the digital temperature value om LCD or 7-Segment Display.
Here, 8051 and ATmega8 microcontrollers are used. The ATmega8 has inbuilt analog to digital converter with six multiplexed channels of 10-bit resolution. This reduces interfacing of external analog to digital converter IC. The analog temperature value is directly applied to input ADC channels of microcontroller. Successive approximation method is used for Analog to digital conversion internally.
But in case of 8051 Microcontroller (AT89C51 is used in this project), it doesn’t have any built-in ADC like ATmega8. Hence, I am going to interface an external ADC IC ADC0804 with 8051 Microcontroller to convert the Analog temperature values to digital values.
Working
After making all the connections and burning the code onto the 8051 Microcontroller, turn ON the power supply. The LM35 Temperature Sensor provides the Analog Temperature Data to ADC0804, which it converts into Digital Values and sends to 8051.
Upon receiving the digital values, the 8051 Microcontroller performs a small calculation and then displays the temperature on the LCD.
Digital Temperature Sensor Circuit using ATmega8
Digital Temperature Sensor Circuit Design
The digital temperature circuit consists of ATmega8 microcontroller, LM35 temperature sensor, 7 segment display. The temperature sensor Lm35 is connected to one of the ADC channels of microcontroller.
ATmega8 has six ADC channels at Port C. PC0-PC5 pins of Atmega8 act as ADC channels. This shows that one can interface six analog values. But only one conversion is done at a time depending on the priority of the input channels. The resolution of ADC is 10 bit. Remember that for conversion Vref and Avcc are externally connected as shown in circuit.
Generally, all the port pins of ATmega8 microcontroller act as normal input /output pins until their special functions are declared. ADC registers inside the controller have to be declared in order make Port C to act as ADC channel.
Lm35 temperature sensor has three terminals. Placing the flat surface towards you first pin is Vcc, Second pin is Output and the third pin is Ground. Output pin of temperature sensor is connected to the first ADC channel i.e. PC0 pin of microcontroller.
Seven segment display has eight pins and one common pin. Leaving Dp, connect all the seven pins to port B. Connect A to PB0, B to PB1,_____, G to PB6. Seven segment display used here is common cathode display. Current limiting resistors were used between controller and the display.