BNO055

Intro to this Experiment

• BNO055 is a system in package.
• A combination of cortex M0, microcontroller, fusion software is responsible of handling everything in the background.
• We are going to play with BNO055 from Raspberry Pi Pico by using MicroPython.

I²C Wiring

• I2C or IIC or SMBus Pins
  • SCL: Clock line
  • SDA: Data line

    Slave1     Master     Slave2
    SCL    <->  SCL   <->    SCL
    SDA    <->  SDA   <->    SDA

Read temperature and absolute orientation

• Following infos are from datasheet
  • The default I2C address of the BNO055 device is 0x29 (Datasheet 4.6 I2C Protocol)
  • The default operation mode after power-on is CONFIGMODE. (3.3 Operation Modes)
  • Incomplete Register Table (4.2.1 Register map Page 0)

  Page   Name              Addr    Default
   0,1   Page ID           0x07    0x00
     0   OPR_MODE          0x3D    0x1C
     0   TEMP              0x34    0x00
     0   CALIB_STAT        0x35    0x00
     0   EUL_Heading_LSB   0x1A    0x00
  

• Setup an i2c obj (API doc)

from machine import Pin, I2C
i2c = I2C(id=0, scl=Pin(5), sda=Pin(4), freq=400000)

• Make sure we are at Page 0 (Different page, different register)

>>> i2c.readfrom_mem(0x29, 0x07, 1)
b'\x00'

• Check if we are at CONFIGMODE

>>> "{0:b}".format(int.from_bytes(i2c.readfrom_mem(0x29, 0x3D, 1), 'little', True))
'10000' # 10000 is xxxx0000

• We read nothing in CONFIGMODE

>>> i2c.readfrom_mem(0x29, 0x34, 1) # TEMP
b'\x00'

• Change operation mode from CONFIGMODE to NDOF

i2c.writeto_mem(0x29, 0x3D, b'\x0C') # 0x0C == xxxx1100

• Read Temperature

>>> temp = i2c.readfrom_mem(0x29, 0x34, 1)
>>> int.from_bytes(temp, 'little', True)
31 # Celsius Deg

• Read Calibration Status

>>> "{0:b}".format(int.from_bytes(i2c.readfrom_mem(0x29, 0x35, 1), 'little', True))
'110100' # Last two zeros means magnetometer is not calibrated

• Shake BNO055 and what happend

>>> "{0:b}".format(int.from_bytes(i2c.readfrom_mem(0x29, 0x35, 1), 'little', True))
'110011' # Calibrated

• Read Heading

import time
while 1:
  print(int.from_bytes(i2c.readfrom_mem(0x29, 0x1A, 2), "little", True) / 16) # 16 is from Table 3-29: Euler angle data representation
  time.sleep(0.2)

Some Soldering Work to enable I2C communication

An important quote from VitallyRaccoon's post: "To configure the module for i2c communication both jumpers should be closed."