Digital Barometer using PIC Microcontroller and MPX4115A Pressure Sensor – XC8
The Motorola MPX4115A is an atmospheric pressure sensor powered by 5V and delivers and output from ~0.25V to ~4.75V based on the pressure detected at room temperature (25°C). The device provides a linear output based on pressure. As the pressure rises, the output voltage of the sensor rises as well with ~0.25V represents <15 kPa pressure relative to a vacuum and ~4.75V represents >115 kPa.
Note that 1 atmosphere of pressure at sea level is equal to 101,325 Pa or 101 kPa. The graph below shows a typical output response of an MPX4115A pressure sensor, below 15KPa and above 115KPa the voltage doesn’t change.The MPX4115A is thus an ideal sensor for microcontroller based barometer or altimeter applications.
- 1.5% Maximum Error over 0° to 85°C
- Ideally suited for Microprocessor or Microcontroller– Based Systems
- Temperature Compensated from –40° to +125°C
- Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package
- Aviation Altimeters
- Industrial Controls
- Engine Control
- Weather Stations and Weather Reporting Devices
As shown on the circuit diagram above, it is very easy to interface the MPX4115A to a PIC, if you are using the 8-pin sensor, connect pin 2 to +5V, pin 3 to ground and the output is on pin 4 (connect to analog pin of PIC). leave the rest unconnected. If you are using the 6-pin sensor, pin 1 is the output (connect to analog pin of PIC), pin 2 to ground and pin 3 to +5V. Leave the rest unconnected.
Note: Pin 1 is noted by the notch in the lead
VDD and VSS of the pic microcontroller is not shown in the circuit diagram. VDD should be connected to +5V and VSS to GND. The MCLR is disabled in software and an internal oscillator clock is selected so no need for external crystal.
A 16 x 2 lines LCD display is connected to PORT B. refer to the Interfacing LCD Display with PIC microcontroller
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