Interface BMI160 with Raspberry Pi Pico & MicroPython

Overview
In this tutorial, we will be
interfacing the BMI160 Accelerometer & Gyroscope
with the
Raspberry Pi Pico
using
MicroPython
. The
BMI160
is a small, low-power, low-noise 16-bit inertial measurement unit that integrates a
3-axis accelerometer
and a
3-axis gyroscope
. It provides precise motion sensing for applications like augmented reality, fitness tracking, and indoor navigation.
This tutorial provides detailed information about the
BMI160 Accelerometer Gyroscope Module
, including its specifications and technical details. First, we will interface the
BMI160
with a
Raspberry Pi Pico
and then write a
MicroPython code
to convert the accelerometer raw values to
Acceleration
and
Tilt Angles
(Pitch & Roll).
Bill of Materials
We will need the following components for this tutorial. You can purchase all the components from the given links.
S.N.
Components Name
Quantity
Purchase Link

Raspberry Pi Pico

Amazon
AliExpress

BMI160 Accelerometer Gyroscope

Amazon
AliExpress

Connecting Wires

Amazon
AliExpress

Breadboard

Amazon
AliExpress
BMI160 3 Axis Accelerometer & Gyroscope
The
BMI160
is a high-performance, small, and ultra-low-power 16-bit Inertial Measurement Unit (IMU) that combines a 3-axis accelerometer and a 3-axis gyroscope in a single package.
Fig: Front & Back of BMI160
It is designed to deliver accurate and reliable motion sensing for a wide range of applications, such as augmented reality, indoor navigation, wearable devices, and gaming. The sensor offers advanced features like motion detection, step counting, and gesture recognition, making it versatile for modern technology needs.
The
BMI160
supports both
I2C
and
SPI
interfaces for communication, making it compatible with a variety of microcontrollers and processors. It has a compact footprint of just
2.5 x 3.0 x 0.8 mm³
, which is smaller than many competing IMUs, such as the MPU6050, and is well-suited for space-constrained devices like wearables. Refer to Bosch
BMI160 Datasheet
for more information.
Technical Specifications of BMI160
Operating Voltage: 1.71 – 3.6 V (Breakout Board operates between 3.2V~6V)
Power Consumption
:
Gyroscope: 900 µA (full operation)
Gyroscope + Accelerometer: 950 µA (full operation)
Accelerometer: 180 µA (full operation)
Suspend Mode: 3 µA
Motion Detection: 200 µA
Acceleration Range: ±2g/±4g/±8g/±16g
Gyroscopes Range: ±125°/s,±250°/s,±500°/s,±1000°/s,±2000°/s
Acceleration Zero-g Offset: ±40mg
Gyroscopes Zero-g Offset: ±10°/s
Interfaces
:
Primary
: I2C or SPI
Secondary
: High-speed SPI for optical image stabilization
Noise Density
:
Accelerometer: 180 µg/√Hz
Gyroscope: 0.008 °/s/√Hz
Programmable Frequency: 25/32Hz~1600Hz
6D Detection and Location
16-bit Data Output
Shock Resistance: 1000gx 200us
2 Independent Programmable Interrupt Generators
In-built 1024 Byte FIFO
Applications of BMI160
Augmented Reality
: Tracks motion for virtual environments.
Indoor Navigation
: Supports step counting and positioning.
Mobile Devices
: For smartphones and smartwatches.
Wearables
: Powers fitness and health devices.
Gaming
: Tracks motion in controllers.
Cameras
: Stabilizes images.
Drones & Toys
: Enables motion sensing.
Pinout of BMI160
Fig: Pinout of BMI160 Gyroscope Accelerometer Module
Pin
Description
VIN
VIN
Power input pin. Accepts
3.3V to 5V
and steps it down for the BMI160 using an onboard regulator.
3.3V
3.3V
Regulated 3.3V output pin.
GND
GND
Ground pin. Connect to the ground of your system.
OCS
OCS
Optional Chip Select for secondary SPI interface (used in optical image stabilization).
INT1
INT1
Interrupt pin 1. Used for motion events or data-ready notifications.
INT2
INT2
Interrupt pin 2. An additional interrupt pin for more advanced use cases.
SCL/SCX
SCL
or
SCX
I2C clock line
when using I2C communication. Acts as
SPI clock (SCX)
in SPI mode.
SDA/SDX
SDA
or
SDX
I2C data line
when using I2C communication. Acts as
SPI data (SDX)
in SPI mode.
CS
CS
Chip Select pin for SPI communication. Used to select the BMI160 during SPI transactions.
SA0
SA0
I2C address selection pin. Connect to
GND
for address
0x68
or to
3.3V
for
0x69
Interfacing BMI160 with Raspberry Pi Pico
Let us interface the BMI160 Gyroscope Accelerometer module with Raspberry Pi Pico Board. We can either use the module in SPI Mode or in I2C Mode. For this tutorial, we are using the I2C Mode as it just requires 2 wires.
Here is an interfacing circuit diagram for the connection between BMI160 and Raspberry Pi Pico Board.
BMI160 Pin
Raspberry Pi Pico
Description
3.3V
3.3V
Power input for the BMI160.
GND
GND
Ground connection.
SCL
GP1
I2C Clock line.
SDA
GP0
I2C Data line.
SA0
GND
Sets I2C address to
0x68
You can use a breadboard to connect the BMI160 with Raspberry Pi Pico as per the circuit diagram.
MicroPython Code
After hardware connection is done, now lets write an
MicroPython Code
to read the Raw Acceleration and Gyroscope Data from BMI160 Module & Raspberry Pi Pico. We will use some mathematical equations to convert the raw values into acceleration and gyroscopic value.
Raw values are converted to 𝑚/𝑠^2 using the formula:
Sensitivity for ±2g is 16384 LSB/g. Adjust if you use a different range.
The angle of rotation around the X-axis is called as Pitch which is calculated using the following formula:
The angle of rotation around the Y-axis is called as Roll which is calculated using the following formula:
This code uses a Raspberry Pi Pico to interface with the BMI160 sensor via I2C. It measures acceleration in m/s² and calculates tilt angles (pitch and roll). Auto-calibration is performed to remove offsets. Accurate readings are printed continuously.

from
machine
import
I2C
Pin
import
math
import
time
# Constants
BMI160_I2C_ADDR
=
0x68
ACCEL_SENSITIVITY
=
16384.0
# ±2g sensitivity for the accelerometer in LSB/g
# Initialize I2C with specified pins
i2c
=
I2C
(

scl
=
Pin
(

)
sda
=
Pin
(

)
freq
=
400000
)
def
write_register
(
addr
reg
data
)
:
""
"Write data to a register."
""
i2c
writeto_mem
(
addr
reg
bytes
(
[
data
]
)
)
def
read_register
(
addr
reg
length
)
:
""
"Read data from a register."
""
return
i2c
readfrom_mem
(
addr
reg
length
)
def
initialize_bmi160
(
)
:
""
"Initialize the BMI160 sensor."
""
# Set accelerometer to normal mode
write_register
(
BMI160_I2C_ADDR
0x7E
0x11
)
# ACC_NORMAL_MODE
time
sleep
(
0.1
)
def
read_raw_acceleration
(
)
:
""
"Read raw acceleration data."
""
data
=
read_register
(
BMI160_I2C_ADDR
0x12

)
# Read accel data
ax_raw
=
int
from_bytes
(
data
[

:

]
'little'
)
(

<<

if
data
[

]
&
0x80
else

)
ay_raw
=
int
from_bytes
(
data
[

:

]
'little'
)
(

<<

if
data
[

]
&
0x80
else

)
az_raw
=
int
from_bytes
(
data
[

:

]
'little'
)
(

<<

if
data
[

]
&
0x80
else

)
return
ax_raw
ay_raw
az_raw
def
auto_calibrate
(
)
:
""
"Perform auto-calibration to remove noise or error."
""
(
"Starting auto-calibration..."
)
num_samples
=

ax_offset
=

ay_offset
=

az_offset
=

for
_
in
range
(
num_samples
)
:
ax_raw
ay_raw
az_raw
=
read_raw_acceleration
(
)
ax_offset
+=
ax_raw
ay_offset
+=
ay_raw
az_offset
+=
az_raw
time
sleep
(
0.01
)
# Small delay between readings
# Calculate average offsets
ax_offset
//= num_samples
ay_offset
//= num_samples
az_offset
//= num_samples
# Assuming the sensor is stable, Z-axis should measure 1g (gravity)
az_offset
-=
int
(
ACCEL_SENSITIVITY
)
(
"Auto-calibration completed."
)
(
"Offsets - X: {}, Y: {}, Z: {}"
format
(
ax_offset
ay_offset
az_offset
)
)
return
ax_offset
ay_offset
az_offset
def
read_acceleration
(
ax_offset