| In this article we look at another acceleration sensor – this time its the BMA400 The BMA400 is the first real ultra-low power acceleration sensor without compromising on performance. Featuring 12-bit digital resolution, continuous measurement and a defined selectable bandwidth combined with ultra-low power the BMA400 allows low-noise measurement of accelerations in three perpendicular axes. The BMA400 thus senses tilt, orientation, tab/double tab, and enables plug ’n’ play step counting with activity recognition especially suited for wearable devices, which need a long-lasting battery lifetime. Thanks to the continuous measurement principle and always-defined bandwidth, the BMA400 is the ideal solution for smart home applications such as smart indoor climate systems and smart home security systems. In the latter, the BMA400 can distinguish between real alarm situations like broken glass and false signals coming from random vibrations. Thereby, the new acceleration sensor avoids false alarms. Features| Parameter | Technical data |
|---|
| Measurement range | ±2 g, ±4 g, ±8 g, ±16 g | | Digital resolution | 12 bit | | Output Data Rate (ODR) | 12.5 Hz to 800 Hz | | Low path filter bandwidth | Selectable 0.48xODR or 0.24xODR | | Current consumption (independent from ODR due to continuous measurement) | Max. performance: 14.5 μA
Typical use case: 5.8 μA
Low power use case: 3.5μA | | Noise density | Max. performance: 180 μg/√Hz (Z: x 1.45)
Typical use case: 300 μg/√Hz (Z: x 1.45)
Low power: 415 μg/√Hz (Z: x 1.45) | | Ultra low power / Auto-wake-up mode | 800 nA @ 25 Hz ODR | | Embedded features | - Step counter (< 4 μA overall)
- Activity recognition (walking, running, standing still)
- Activity change
- Orientation
- Tab/Double tab (< 8 μA overall)
- General interrupt 1 and 2 (programmable via thresholds, timer, logical AND/OR operations)
- 1 kB FIFO
| | Offset | ±80 mg | | TCO | ±1 mg/K | | Interface | SPI & I²C & 2 Interrupt pins | | Supply voltage | 1.71 V up to 3.6 V |
Parts Required Schematic/Connection  arduino and BMA400 Code ExampleThis uses the library from https://github.com/Seeed-Studio/Grove_3Axis_Digital_Accelerometer_BMA400 #include "BMA400.h"
float x = 0, y = 0, z = 0;
int16_t temp = 0;
void setup(void)
{
Wire.begin();
Serial.begin(115200);
while(!Serial);
Serial.println("BMA400 Raw Data");
while(1)
{
if(bma400.isConnection())
{
bma400.initialize();
Serial.println("BMA400 is connected");
break;
}
else Serial.println("BMA400 is not connected");
delay(2000);
}
}
void loop(void)
{
bma400.getAcceleration(&x, &y, &z);
temp = bma400.getTemperature();
Serial.print(x);
Serial.print(",");
Serial.print(y);
Serial.print(",");
Serial.print(z);
Serial.print(",");
Serial.print(temp);
Serial.println();
delay(500);
} OutputOpen the serial monitor and you should see something like this BMA400 is connected
564.45,808.59,201.17,23
1029.30,-105.47,400.39,23
908.20,-189.45,359.38,23
902.34,-265.63,345.70,23 Linkshttps://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMA400-DS000.pdf https://github.com/BoschSensortec/BMA400-API https://www.bosch-sensortec.com/bst/products/all_products/bma400_1 In this article we look at another sensor – this time its the LIS3MDL which is a 3-axis MEMS magnetic field sensor, digital output, I2C, SPI, low power mode, high performance The LIS3MDL has user-selectable full scales of ±4/±8/±12/±16 gauss.
The self-test capability allows the user to check the functioning of the sensor in the final application.
The device may be configured to generate interrupt signals for magnetic field detection.
The LIS3MDL includes an I2C serial bus interface that supports standard and fast mode (100 kHz and 400 kHz) and SPI serial standard interface.
The LIS3MDL is available in a small thin plastic land grid array package (LGA) and is guaranteed to operate over an extended temperature range of -40 °C to +85 °C. Features- Wide supply voltage, 1.9 V to 3.6 V
- Independent IO supply (1.8 V)
- ±4/±8/±12/±16 gauss selectable magnetic full scales
- Continuous and single-conversion modes
- 16-bit data output
- Interrupt generator
- Self-test
- I2C/SPI digital output interface
- Power-down mode / low-power mode
Parts Required Schematic/ConnectionCouldn’t find a good fritzing part or image to use, this is the sensor I bought  
As an added bonus here is the schematic for one of these modules 
| Arduino | Sensor | | 3.3v | Vcc | | Gnd | Gnd | | SDA (A4) | SDA | | SCL (A5) | SCL |
Code ExampleThis uses the library from https://github.com/pololu/lis3mdl-arduino /*
The sensor outputs provided by the library are the raw 16-bit values
obtained by concatenating the 8-bit high and low magnetometer data registers.
They can be converted to units of gauss using the
conversion factors specified in the datasheet for your particular
device and full scale setting (gain).
Example: An LIS3MDL gives a magnetometer X axis reading of 1292 with its
default full scale setting of +/- 4 gauss. The GN specification
in the LIS3MDL datasheet (page 8) states a conversion factor of 6842
LSB/gauss (where LSB means least significant bit) at this FS setting, so the raw
reading of 1292 corresponds to 1292 / 6842 = 0.1888 gauss.
*/
#include <Wire.h>
#include <LIS3MDL.h>
LIS3MDL mag;
char report[80];
void setup()
{
Serial.begin(9600);
Wire.begin();
if (!mag.init())
{
Serial.println("Failed to detect and initialize magnetometer!");
while (1);
}
mag.enableDefault();
}
void loop()
{
mag.read();
snprintf(report, sizeof(report), "M: %6d %6d %6d",
mag.m.x, mag.m.y, mag.m.z);
Serial.println(report);
delay(100);
} OutputOpen the serial monitor and you should see something like this M: -1934 5556 6732
M: -2222 5096 6958
M: -1508 5329 7391
M: -1174 5782 7194
M: -119 6447 6429
M: 447 6333 4702
M: 92 6073 4256
M: -1190 6107 5068
M: -1401 5808 6758
M: -502 5195 7839
M: 740 4453 8173
M: 1327 3639 8161
M: 1421 3006 4294 Linkshttps://www.st.com/resource/en/datasheet/lis3mdl.pdf In this article we look at another absolute pressure sensor – this time its the LPS22HB 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 Schematic/Connection  arduino and LPS22HB Code ExampleThis uses the library from hhttps://github.com/adrien3d/IO_LPS22HB /***************************************************************************
This is a library for the LPS22HB Absolute Digital Barometer
Designed to work with all kinds of LPS22HB Breakout Boards
These sensors use I2C, 2 pins are required to interface, as this :
VDD to 3.3V DC
SCL to A5
SDA to A4
GND to common groud
Written by Adrien Chapelet for IoThings
***************************************************************************/
#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);
} OutputOpen the serial monitor and you should see something like this IoThings LPS22HB Arduino Test
Who Am I? 0xB1 (expected: 0xB1)
P=982.52 mbar, T=18.21C
P=982.56 mbar, T=18.25C
P=982.51 mbar, T=18.26C
P=982.52 mbar, T=18.27C
P=982.54 mbar, T=18.27C
P=982.55 mbar, T=18.27C
P=982.51 mbar, T=18.26C
P=982.55 mbar, T=18.26C
P=982.55 mbar, T=18.26C Linkshttps://www.st.com/resource/en/datasheet/lps22hb.pdf In this article we look at a digital geomagnetic sensor – this time its the BMM150 BMM150 is a low power and low noise 3-axis digital geomagnetic sensor to be used in compass applications. The 12-pin wafer level chip scale package (WLCSP) with a footprint of 1.56 x 1.56 mm² and 0.60 mm height provides highest design flexibility to the developer of mobile devices. Applications like virtual reality or gaming on mobile devices such as mobile phones, tablet PCs or portable media players require 9-axis inertial sensing including magnetic heading information. Due to the stable performance over a large temperature range, the BMM150 is also especially suited for supporting drones in accurate heading. BMM150 can be used with an inertial measurement unit (IMU) consisting of a 3-axis accelerometer and a 3-axis gyroscope like Bosch Sensortec’s BMI055. Features| Parameter | Technical data |
|---|
| Package | CSWLP- (12 pin)
1.56×1.56×0.6 mm³
0.4 mm diagonal ball pitch | | Temperature range | -40°C … +85°C | | Digital interfaces | I²C and SPI
(2 interrupt pins) | | Resolution | 0.3μT | | Supply voltage | VDD: 1.62V to 3.6V
VDDIO: 1.2V to 3.6V | | Zero-B offset | ±50μT | | Non-linearity | <1% FS | | Magnetic range typ. | ±1300μT (x,y-axis)
±2500μT (z-axis) | | Average current consumption | 170 μA (low power preset)
500 μA (normal mode) | | Interrupts | New data, magnetic threshold high / low |
Parts Required Schematic/Connection  arduino and BMM150 Code ExampleThis uses the library from https://github.com/Seeed-Studio/Grove_3_Axis_Compass_V2.0_BMM150 #include <Arduino.h>
#include <Wire.h>
// libraries
#include "bmm150.h"
#include "bmm150_defs.h"
BMM150 bmm = BMM150();
void setup()
{
Serial.begin(9600);
if(bmm.initialize() == BMM150_E_ID_NOT_CONFORM) {
Serial.println("Chip ID can not read!");
while(1);
} else {
Serial.println("Initialize done!");
}
}
void loop()
{
bmm150_mag_data value;
bmm.read_mag_data();
value.x = bmm.raw_mag_data.raw_datax;
value.y = bmm.raw_mag_data.raw_datay;
value.z = bmm.raw_mag_data.raw_dataz;
float xyHeading = atan2(value.x, value.y);
float zxHeading = atan2(value.z, value.x);
float heading = xyHeading;
if(heading < 0)
heading += 2*PI;
if(heading > 2*PI)
heading -= 2*PI;
float headingDegrees = heading * 180/M_PI;
float xyHeadingDegrees = xyHeading * 180 / M_PI;
float zxHeadingDegrees = zxHeading * 180 / M_PI;
Serial.print("Heading: ");
Serial.println(headingDegrees);
delay(100);
} OutputOpen the serial monitor and you should see something like this – the results would have been more interesting if I moved the sensor but I was checking the stability Heading: 261.09
Heading: 262.21
Heading: 261.05
Heading: 260.50
Heading: 260.42
Heading: 260.13
Heading: 260.81
Heading: 259.46 Linkshttps://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMM150-DS001.pdf https://github.com/BoschSensortec/BMM150-Sensor-API | Subscribe to Arduinolearning via Email |
