The technology of the air pressure sensor has progressed to the point now where it can be easily included in pocket-sized electronic widgets, such as cell phones, GPS devices, bike speedometers, and now even wrist-watches. Some of the more recent ones come in very small IC packages (even less than 5mm * 5mm), and have extremely low energy consumption (less than 3uA). They offer extreme precision and enough resolution to detect a tiny change in altitude (10 to 25cms in altitude). They can be hooked up to an existing circuit via a simple serial communication interface, such as SPI or I2C.
The analogue outputs of the previous versions of sensors have been replaced by digital outputs, so the analogue to digital conversion occurs right within the chip. This minimizes the length of the analogue signal lines and reduces interference for much higher precision. They use a sensor that is sensitive to both pressure changes and temperature changes, which means that temperature readings can be added as well.
In order to know how pressure measurements are made, it would help to grasp the difference between relative pressure and absolute pressure. Relative pressure sensors are used for most applications, for example tire pressure and blood pressure readings. In these type of sensors, the pressure being measured is usually referenced relative to background air pressure. In some industrial applications, this reference value could be a variable pressure of another liquid or gas. The reading from a relative pressure measurement is of course the difference between the two pressures.
Some applications require an absolute pressure reading, for example barometric pressures, atmospheric pressures, altimeter pressures, and deep vacuum pressures. According to the definition of absolute pressure, the pressure being measured is referenced against a perfect vacuum. But in actual applications, this reference may be any recurring value of pressure, eg average atmospheric pressure at sea level.
Pressure sensors enable you to predict weather - changes in air pressure frequently accompany localised rainfall for example, or decent weather. They can also help with altitude measurements (this is how altitude is measured on an aircraft for instance). As these sensors become smaller, they can add weather prediction or altitude measurements to applications where this was not possible in the past.
The analogue outputs of the previous versions of sensors have been replaced by digital outputs, so the analogue to digital conversion occurs right within the chip. This minimizes the length of the analogue signal lines and reduces interference for much higher precision. They use a sensor that is sensitive to both pressure changes and temperature changes, which means that temperature readings can be added as well.
In order to know how pressure measurements are made, it would help to grasp the difference between relative pressure and absolute pressure. Relative pressure sensors are used for most applications, for example tire pressure and blood pressure readings. In these type of sensors, the pressure being measured is usually referenced relative to background air pressure. In some industrial applications, this reference value could be a variable pressure of another liquid or gas. The reading from a relative pressure measurement is of course the difference between the two pressures.
Some applications require an absolute pressure reading, for example barometric pressures, atmospheric pressures, altimeter pressures, and deep vacuum pressures. According to the definition of absolute pressure, the pressure being measured is referenced against a perfect vacuum. But in actual applications, this reference may be any recurring value of pressure, eg average atmospheric pressure at sea level.
Pressure sensors enable you to predict weather - changes in air pressure frequently accompany localised rainfall for example, or decent weather. They can also help with altitude measurements (this is how altitude is measured on an aircraft for instance). As these sensors become smaller, they can add weather prediction or altitude measurements to applications where this was not possible in the past.
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Embedded Journeys is a great website for finding fun electronic modules eg the MS5611 air pressure sensor module or helpful things like a real time clock module.
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