The BMA250E is an advanced, ultra-small, triaxial, low-g acceleration sensor with digital interfaces, aiming for low-power consumer electronics applications. Featuring 10 bit digital resolution, the BMA250E allows low-noise measurement of accelerations in 3 perpendicular axes.
A typical module
technical Information
| Parameter | Technical data |
|---|---|
| Digital resolution | 10 bit |
| Resolution (in ±2g range) |
3.9 mg |
| Measurement ranges (programmable) |
±2 g, ±4 g, ±8 g, ±16 g |
| Sensitivity (calibrated) | ±2 g: 256 LSB/g ±4 g: 128 LSB/g ±8 g: 64 LSB/g ±16 g: 32 LSB/g |
| Zero-g offset (typ., over life-time) | ±80 mg |
| Noise density (typ.) | 400 μg/√Hz |
| Bandwidths (programmable) | 1000 Hz … 8 Hz |
| Digital inputs/outputs | SPI & I²C, 2x digital interrupt pins |
| Supply voltage (VDD) | 1.62 V … 3.6 V |
| I/0 supply voltage (VDDIO) | 1.2 V … 3.6 V |
| Temperature range | -40 … +85°C |
| Current consumption – full operation – low-power mode |
130 μA (@ 2 kHz data rate) 6.5 μA (@ 40 Hz data rate) |
| LGA package | 2 x 2 x 0.95 mm³ |
| Interrupts | – Data-ready (e. g. for processor synchronization) – Any-motion (slope) detection (e. g. for wake-up) – Tap sensing (e. g. for tap-sensitive UI control) – Orientation change recognition (e. g. for portrait/landscape switching) – Flat detection (e. g. for position sensitive switching) – Low-g / high-g detection (e. g. for shock and free-fall detection) – No-motion (e.g. for power saving) |
Connection
| Raspberry PI | Module |
| 3.3v | Vcc |
| Gnd | Gnd |
| SDA | SDA |
| SCL | SCL |
Code
[codesyntax lang=”python”]
import smbus
import time
# Get I2C bus
bus = smbus.SMBus(1)
# BMA250 address, 0x18(24)
# Select range selection register, 0x0F(15)
# 0x03(03) Set range = +/-2g
bus.write_byte_data(0x19, 0x0F, 0x03)
# BMA250 address, 0x18(24)
# Select bandwidth register, 0x10(16)
# 0x08(08) Bandwidth = 7.81 Hz
bus.write_byte_data(0x19, 0x10, 0x08)
time.sleep(0.5)
# BMA250 address, 0x18(24)
# Read data back from 0x02(02), 6 bytes
# X-Axis LSB, X-Axis MSB, Y-Axis LSB, Y-Axis MSB, Z-Axis LSB, Z-Axis MSB
data = bus.read_i2c_block_data(0x19, 0x02, 6)
# Convert the data to 10 bits
xAccl = (data[1] * 256 + (data[0] & 0xC0)) / 64
if xAccl > 511 :
xAccl -= 1024
yAccl = (data[3] * 256 + (data[2] & 0xC0)) / 64
if yAccl > 511 :
yAccl -= 1024
zAccl = (data[5] * 256 + (data[4] & 0xC0)) / 64
if zAccl > 511 :
zAccl -= 1024
# 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
[/codesyntax]
Output
Link
CJMCU-250E BMA250E low g three axis accelerometer sensor module MEMS
