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 (25Ā°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 thatĀ 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 doesnāt change.The MPX4115A is thus an ideal sensor for microcontroller based barometer or altimeterĀ applications.
FeaturesĀ
- 1.5% Maximum Error over 0Ā° to 85Ā°C
- Ideally suited for Microprocessor or Microcontrollerā Based Systems
- Temperature Compensated from ā40Ā° to +125Ā°C
- Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package
Application Examples
- Aviation Altimeters
- Industrial Controls
- Engine Control
- Weather Stations and Weather Reporting Devices
Ā Circuit diagram
As shown on the circuit diagram above, it is very easy to interface the MPX4115A to a PIC, if you are using theĀ 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).Ā leave the rest unconnected. If you are using the 6-pin sensor, pin 1 is the output (connect to analog pin of PIC),Ā 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 theĀ Interfacing LCD Display with PIC microcontrollerĀ
For more detail: Digital Barometer using PIC Microcontroller and MPX4115A Pressure Sensor ā XC8
