In this article we look at another pressure sensor – this time its the LPS22HB piezoresistive absolute pressure sensor and we will connect it to our Microbit
This is the sensor I used
Here is some technical information about this sensor
The LPS22HB is an ultra-compact piezoresistive absolute pressure sensor which functions as a digital output barometer. The device comprises a sensing element and an IC interface which communicates through I2C or SPI from the sensing element to the application.
The sensing element, which detects absolute pressure, consists of a suspended membrane manufactured using a dedicated process developed by ST.
The LPS22HB is available in a full-mold, holed LGA package (HLGA). It is guaranteed to operate over a temperature range extending from -40 °C to +85 °C. The package is holed to allow external pressure to reach the sensing element.
Features
- 260 to 1260 hPa absolute pressure range
- Current consumption down to 3 μA
- High overpressure capability: 20x full-scale
- Embedded temperature compensation
- 24-bit pressure data output
- 16-bit temperature data output
- ODR from 1 Hz to 75 Hz
- SPI and I²C interfaces
- Embedded FIFO
- Interrupt functions: Data Ready, FIFO flags, pressure thresholds
- Supply voltage: 1.7 to 3.6 V
- High shock survivability: 22,000 g
Parts Required
I used an expansion board connected to the Micro:bit, this makes it easier to connect sensors using connecting wire
Schematic/Connection
I used the I2C connection for the sensor
| Microbit | Sensor |
| 3v3 | 3v3 |
| Gnd | Gnd |
| SDA – 20 | SDA |
| SCL – 19 | SCL |
Code Example
This uses the library from hhttps://github.com/adrien3d/IO_LPS22HB
[codesyntax lang=”cpp”]
#include <Wire.h>
#include "IO_LPS22HB.h"
IO_LPS22HB lps22hb;
void setup()
{
Serial.begin(9600);
Serial.println("IoThings LPS22HB Arduino Test");
lps22hb.begin(0x5D);
byte who_am_i = lps22hb.whoAmI();
Serial.print("Who Am I? 0x");
Serial.print(who_am_i, HEX);
Serial.println(" (expected: 0xB1)");
if (who_am_i != LPS22HB_WHO_AM_I_VALUE)
{
Serial.println("Error while retrieving WHO_AM_I byte...");
while (true) {
// loop forever
}
}
}
void loop()
{
Serial.print("P=");
Serial.print(lps22hb.readPressure());
Serial.print(" mbar, T=");
Serial.print(lps22hb.readTemperature());
Serial.println("C");
delay(300);
}
[/codesyntax]
Output
Open the serial monitor and you should see something like this
P=1014.41 mbar, T=23.33C
P=1014.42 mbar, T=23.41C
P=1014.41 mbar, T=23.45C
P=1014.41 mbar, T=23.47C
P=1014.40 mbar, T=23.45C
P=1014.39 mbar, T=23.40C
Links
https://www.st.com/resource/en/datasheet/lps22hb.pdf