# Pressure sensor

For the project, we use MS5837-30BA (Bar30 High-Resolution 300m Depth/Pressure Sensor) from Bluerobotics .

**The description of the sensor from** [**http://www.bluerobotics.com/store/electronics/bar30-sensor-r1/**](http://www.bluerobotics.com/store/electronics/bar30-sensor-r1/) **:** 

The *Bar30* pressure sensor is a high-pressure, high-resolution pressure sensor that is sealed from the water and ready to install in a [watertight enclosure](https://www.bluerobotics.com/product-category/watertight-enclosures/) on your ROV or AUV. With 0.2 mbar resolution, it has an amazing depth measurement resolution of 2mm in the water column!

The sensor is the Measurement Specialties MS5837-30BA, which can measure up to 30 bar (300m/1000ft depth) and communicates over I2C. It operates on 3.3V I2C voltage but can accept power input up to 5.5V. It comes standard with a 4-pin DF13 connector that is compatible with most [DroneCode](http://dronecode.org) compatible boards including the APM2.6, PixHawk, and others.

This sensor includes a temperature sensor accurate to ±1°C, with data also accessible through I2C. If you need something with more temperature accuracy, please check out the [*Celsius* Temperature Sensor](https://www.bluerobotics.com/store/electronics/celsius-sensor-r1/).

The anodized aluminum body was designed around the cable penetrator design and is compatible with all of the [watertight enclosures](https://www.bluerobotics.com/product-category/watertight-enclosures/).

**To summarize, there are some noticeable features:**

0.2 cm resoulution (in freshwater), but not confusing with absolute accuracy.

measure up to 30bar = 30\*1000 mBar = 30\*1000\*0.01 m = 300 m

From datasheet of the sensor, the accuracy +/-50 mBar (aka. +/-50cm in freshwater)

**By experiment and from Bluerobotics' forum**:

There is significant [drifting of absolute value](http://discuss.bluerobotics.com/t/bar30-pressure-sensor-drifting-absolute-value/990)

Problem of repeatibility of the values. Fonz (fernandoFonseca) recommends using [Sparkfun Breakout MS5803-14BA (but not waterproof)](https://www.sparkfun.com/products/12909)

After some period of time (can be up to 1 hour), values read from the sensor become stable