Low cost temperature data logger using PIC

Posted on Feb 4, 2014

This project describes an easy and inexpensive way of adding a digital thermometer and data logging feature to a PC. It involves a PIC microcontroller that gets the surrounding temperature information from the Microchip MCP9701 sensor, and sends it to a PC through an USB-UART interface. The USB port of the PC is also used to power the device. The

Low cost temperature data logger using PIC
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open-source Processing programming platform is used to develop a PC application that displays the temperature in a graphics window on the computer screen. The PC application also records the temperature samples plus date and time stamps on an ASCII file. This project is based on Microchip`s PIC12F1822 microcontroller from the enhanced mid-range PIC family. It has got 8-pins in total and the power supply voltage range of 1. 8V to 5. 5V. The microcontroller has four 10-bit ADC channels and one Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module for serial communication. The temperature sensor used here is MCP9701A, which is a Low-Power Linear Active Thermistor IC from Microchip Technology. The range of temperature measurement is from -40 °C to +125 °C. The output voltage of the sensor is directly proportional to the measured temperature and is calibrated to a slope of 19. 53mV/ °C. It has a DC offset of 400mV, which corresponds to 0 °C. The offset allows reading negative temperatures without the need for a negative supply. The output of the sensor is fed to one of the ADC channels of the PIC12F1822 microcontroller for A/D conversion. The internal fixed voltage reference (FVR) module is configured to generate a stable 2. 048 V reference voltage for A/D conversion. The use of FVR module ensures the accuracy of the A/D conversion even when the supply voltage is not stable. The PIC12F1822...

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