digital thermometer using pic microcontroller and MCP9700
In this article you will learn, how to design digital thermometer using pic microcontroller and MCP9700? You will learn how to interface MCP9700 with PIC16F877A microcontroller? How to measure temperature using MCP9700 low power voltage output temperature sensor. Before reading this article you should have idea of lcd interfacing with pic microcontroller and how to measure analog voltage using pic microcontroller? If you don’t know about them, I recommend you to read followings articles first. After reading following article, you will be able to understand circuit diagram and code of MCP9700 based digital thermometer using pic microcontroller.
MCP9700 temperature sensor
It is voltage output sensor. It is low power and low cost temperature sensor. It converts temperature into voltage. Voltage can be easily measured with the help of microcontroller. Microcontroller reads voltage with the help of analog to digital converter. Measured voltage converted back into temperature using mathematical manipulation in programming. I will discuss it later in programming part of this article. It can give accuracy up to ±4%°C. It can measure temperature from -40°C to +125°C. It consumes a minimum amount of operating current 6μA. It can derive large capacitive loads.
MCP9700 temperature sensor working
MCP9700 temperature sensor consists of PN junction diode. The main temperature sensing element is PN junction diode. PN junction electrical characteristics contains temperature coefficient which provides change in voltage with change in temperature. The change in voltage is scaled with change in temperature according to following step per division:
MCP9700 interfacing with microcontroller
MCP9700 based digital thermometer does not require any external components. It does not require any signal conditioning circuit. It can be directly interfaced with ADC of microcontroller. In MCP9700 1°C = 10.0 mV . General interfacing diagram of MCP9700 is shown below:
circuit diagram of MCP9700 interfacing with pic microcontroller
Its interfacing diagram with pic microcontroller is shown below. LCD is interfaced with pic microcontroller to display temperature. PIC16F877A microcontroller measure output voltage of temperature sensor with the help of ADC as shown in figure below:
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- circuit diagram of digital thermometer using microcontroller