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  • Digital Pressure Sensor

  • Created: Jan 04, 2016

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The MPL115A1T1 device is a simple pressure sensor with SPI digital output devised for cost-effective applications. It utilizes a Micro Electro Mechanical Systems (MEMS) pressure sensor with a conditioning integrated circuit to give an accurate pressure data. An integrated analog-to-digital converter (ADC) provides digitized temperature and pressure outputs through the device serial peripheral interface. The MPL115A1T1 operates as a SPI slave with bus speeds up to 8 Mbps. It senses 50kPa to 115kPa absolute pressure with ±1kPa accuracy.

This digital pressure sensor reference design is made up of a MPL115A1T1 pressure sensor, a microcontroller, and an LCD display with an I2C backpack. The MPL115A1T1 interfaces to the microcontroller via SPI port. Initially, all circuit elements are active. The impedance of the SPI port pins is high and all associated registers are cleared. Then, the device enters standby mode and the process of reading the coefficient data will be executed. After reading the coefficient data, the microcontroller sends a conversion command to the MPL115A1T1 device to get a pressure reading. The MPL115A1T1 senses the temperature and pressure and put the result of the conversion into the pressure and temperature ADC output registers. The microcontroller reads the result from the ADC output registers and calculates the compensated pressure using the coefficient data and the raw sampled pressure and temperature ADC output values. The calculated result will be displayed on the LCD via I2C port of the microcontroller.

The MPL115A1T1 device operates with a 2.375V to 5.5V power supply with a current consumption of around 1 to 10uA. In this reference design, the voltage supply of the device is 5V since the microcontroller and the LCD requires a 5V supply. The resolution of the MPL115A1T1 device is typically 0.15kPa. Its conversion time takes around 1.6 to 3ms. The small size, low power consumption, high accuracy, and digitized output features of the MPL115A1T1 device makes it ideal for pressure measurement applications. It can be used in applications such as altimeters, weather stations, hard disk drives, industrial equipment, health monitoring, or air control systems.