Beaglebone and LSM303DLHC sensor example in Python

The LSM303DLHC is a system-in-package featuring a 3D digital linear acceleration sensor and a 3D digital magnetic sensor.

The LSM303DLHC has linear acceleration full scales of ±2g / ±4g / ±8g / ±16g and a magnetic field full scale of ±1.3 / ±1.9 / ±2.5 / ±4.0 / ±4.7 / ±5.6 / ±8.1 gauss.

The LSM303DLHC includes an I2C serial bus interface that supports standard and fast mode 100 kHz and 400 kHz. The system can be configured to generate interrupt signals by inertial wake-up/free-fall events as well as by the positionof the device itself. Thresholds and timing of interrupt generators are programmable by the end user. Magnetic and accelerometer blocks can be enabled or put into power-down mode separately

Features

3 magnetic field channels and 3 acceleration channels
From ±1.3 to ±8.1 gauss magnetic field full scale
±2g/±4g/±8g/±16g linear acceleration full scale
16-bit data output
I2C serial interface
Analog supply voltage 2.16 V to 3.6 V
Power-down mode / low-power mode
2 independent programmable interrupt generators for free-fall and motion detection
Embedded temperature sensor
Embedded FIFO
6D/4D-orientation detection

Parts Required

Connection

Code

This is a python example, I used  the cloud9 IDE

[codesyntax lang=”python”]

# Distributed with a free-will license.
# Use it any way you want, profit or free, provided it fits in the licenses of its associated works.
# LSM303DLHC
# This code is designed to work with the LSM303DLHC_I2CS I2C Mini Module available from ControlEverything.com.
# https://www.controleverything.com/products

import smbus
import time

# Get I2C bus
bus = smbus.SMBus(2)

# LSM303DLHC Accl address, 0x19(25)
# Select control register1, 0x20(32)
#		0x27(39)	Acceleration data rate = 10Hz, Power ON, X, Y, Z axis enabled
bus.write_byte_data(0x19, 0x20, 0x27)
# LSM303DLHC Accl address, 0x19(25)
# Select control register4, 0x23(35)
#		0x00(00)	Continuos update, Full scale selection = +/-2g,
bus.write_byte_data(0x19, 0x23, 0x00)

time.sleep(0.5)

# LSM303DLHC Accl address, 0x19(25)
# Read data back from 0x28(40), 2 bytes
# X-Axis Accl LSB, X-Axis Accl MSB
data0 = bus.read_byte_data(0x19, 0x28)
data1 = bus.read_byte_data(0x19, 0x29)

# Convert the data
xAccl = data1 * 256 + data0
if xAccl > 32767 :
	xAccl -= 65536

# LSM303DLHC Accl address, 0x19(25)
# Read data back from 0x2A(42), 2 bytes
# Y-Axis Accl LSB, Y-Axis Accl MSB
data0 = bus.read_byte_data(0x19, 0x2A)
data1 = bus.read_byte_data(0x19, 0x2B)

# Convert the data
yAccl = data1 * 256 + data0
if yAccl > 32767 :
	yAccl -= 65536

# LSM303DLHC Accl address, 0x19(25)
# Read data back from 0x2C(44), 2 bytes
# Z-Axis Accl LSB, Z-Axis Accl MSB
data0 = bus.read_byte_data(0x19, 0x2C)
data1 = bus.read_byte_data(0x19, 0x2D)

# Convert the data
zAccl = data1 * 256 + data0
if zAccl > 32767 :
	zAccl -= 65536

# LSM303DLHC Mag address, 0x1E(30)
# Select MR register, 0x02(02)
#		0x00(00)	Continous conversion mode
bus.write_byte_data(0x1E, 0x02, 0x00)
# LSM303DLHC Mag address, 0x1E(30)
# Select CRA register, 0x00(00)
#		0x10(16)	Temperatuer disabled, Data output rate = 15Hz
bus.write_byte_data(0x1E, 0x00, 0x10)
# LSM303DLHC Mag address, 0x1E(30)
# Select CRB register, 0x01(01)
#		0x20(32)	Gain setting = +/- 1.3g
bus.write_byte_data(0x1E, 0x01, 0x20)

time.sleep(0.5)

# LSM303DLHC Mag address, 0x1E(30)
# Read data back from 0x03(03), 2 bytes
# X-Axis Mag MSB, X-Axis Mag LSB
data0 = bus.read_byte_data(0x1E, 0x03)
data1 = bus.read_byte_data(0x1E, 0x04)

# Convert the data
xMag = data0 * 256 + data1
if xMag > 32767 :
	xMag -= 65536

# LSM303DLHC Mag address, 0x1E(30)
# Read data back from 0x05(05), 2 bytes
# Y-Axis Mag MSB, Y-Axis Mag LSB
data0 = bus.read_byte_data(0x1E, 0x07)
data1 = bus.read_byte_data(0x1E, 0x08)

# Convert the data
yMag = data0 * 256 + data1
if yMag > 32767 :
	yMag -= 65536

# LSM303DLHC Mag address, 0x1E(30)
# Read data back from 0x07(07), 2 bytes
# Z-Axis Mag MSB, Z-Axis Mag LSB
data0 = bus.read_byte_data(0x1E, 0x05)
data1 = bus.read_byte_data(0x1E, 0x06)

# Convert the data
zMag = data0 * 256 + data1
if zMag > 32767 :
	zMag -= 65536

# Output data to screen
print "Acceleration in X-Axis : %d" % xAccl
print "Acceleration in Y-Axis : %d" % yAccl
print "Acceleration in Z-Axis : %d" % zAccl
print "Magnetic field in X-Axis : %d" %xMag
print "Magnetic field in Y-Axis : %d" %yMag
print "Magnetic field in Z-Axis : %d" %zMag

[/codesyntax]

Output

Here are a couple of runs moving the sensor around

debian@beaglebone:/var/lib/cloud9/$ python LSM303DLHC.py
Acceleration in X-Axis : 3072
Acceleration in Y-Axis : 15872
Acceleration in Z-Axis : -256
Magnetic field in X-Axis : 6
Magnetic field in Y-Axis : -459
Magnetic field in Z-Axis : 237
debian@beaglebone:/var/lib/cloud9/$ python LSM303DLHC.py
Acceleration in X-Axis : -4544
Acceleration in Y-Axis : 960
Acceleration in Z-Axis : 8192
Magnetic field in X-Axis : 83
Magnetic field in Y-Axis : -26
Magnetic field in Z-Axis : 590

Link

https://www.st.com/resource/en/datasheet/DM00027543.pdf