Breakout board based on the OMRON 2SMPB-02E pressure and humidity sensor. It allows to detect atmospheric pressure and temperature. Designed for creating weather stations or applications where it is important to know these parameters, such as air mass meters and altimeters. The breakout has a low drop linear voltage regulator and a MOSFET adapter for the I²C-Bus interface. The latter is useful for translating the logic levels supported by the sensor to adapt them to the standard TTLs of traditional logic boards and to Arduino.

Using the breakout with Arduino and a simple Sketch, thanks to which we will print on the serial monitor the values ​​read in the surrounding environment; can be used for many applications, ranging from simple weather stations to dynamic model aircraft and visual flight, to the realization of altimeters for every field of use, wearable electronics and air mass meters (to determine which pressure is not sufficient but is necessary also know the air density, related to temperature).

Note. Breakout board is sold already assembled and tested. Arduino and jumpers are not included (see related products).

Let's now let you see how we tried the breakout board in combination with Arduino Uno, which based on the expected sketch will acquire the data from the Omron sensor and print them on serial, so that by starting the Arduino IDE we will be able to visualize them on the Serial Monitor.
The wiring diagram you see below proposes the connection of the board to the Arduino Uno Rev3 expansion connectors. Only six wires are used for the connection, namely:

• two for the I²C-Bus lines, since it is enough for us to be able to carry out an essential communication in order to have the measurements to pass to the serial line; to be precise, we connect Arduino SCL to the breakout board and SDA of Arduino to SDI of the breakout board;
• a common mass for the GND supplying the same;
• an additional mass to set the breakout board SDO line fixed to logical zero, since we will operate in I²C-Bus mode and place this address pin at 0, thus setting the device address to 0;
• one that takes Arduino UNO 3V3 pin to the breakout board RST input to disable sensor reset.

The tolerance on the absolute pressure measurement is, in an operating temperature range of 0 and 65 ° C, ± 50 Pa, while between -20 ° C and 0 ° C rises to ± 80 Pa. Instead on the relative pressure it is ± 3.9 Pa. The resolution (ie the minimum detectable gradient) on the pressure measurement amounts to just
0.06 Pa, which makes it more than suitable for the sensor to work as an altimeter, as it can detect even slight variations in pressure that correspond to small changes in altitude.
As for the temperature measurement, the internal sensor detects (between 30 to 110 kPa) in a range between -20 ° C and + 65 ° C, with a resolution of just 0.0002 ° C, therefore very high, and a tolerance of ± 2 ° C. As for the power supply, the sensor requires a continuous voltage value between 1.7 and 3.6Vdc, while the average absorption, assuming an operating cycle that includes 1 sample / s in Ultra High Accuracy mode (with very high precision with 24-bit data output) is just 21.4 μA, which makes the device ideal for very low-power, battery-powered or energy-harvesting solutions. In this regard, consider that the Omron device supports a sleep mode, in which it is brought to rest completely absorbing just 2 microamps.
As for the continuous operation, for the pressure measurement we are on an absorption of the order of 0.64 ÷ 0.8 mA, while for the temperature measuring section we are between 0.41 and 0.52 mA; the difference depends on the sensor used. The logic levels on the data channels consequently go to the supply voltage, therefore in output they are proportional:
if we feed the 3V chip, levels 1 and 0 will be 3V and 0V respectively. The pin-out of the component is as follows:

1) asynchronous reset (active at logic 1);
2) CSB - setting the communication mode;
3) SDI - SDA of the I-C-Bus and input data of the SPI;
4) SCK - communication clock;
5) SDO - SPI data output;
6) VDDIO - digital I / O power supply;
7) GND - common mass;
8) VDD - power supply;
9) VPP - internal OTP memorization pulse.

• Datasheet Omron 2SMPB-02E Sensor
• Omron sensor management library 2SMPB-02E