Add I2C implementation #52
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@asymingt hey hey this is awesome stuff! I try to carve some time out soon to review this and test the UART stuff. So cool btw to hear this is working on a google coral board - haven't gotten one myself but they definitely look cool! |
@flynneva, glad you appreciate the contribution. The code does work, but it's not particularly high-performance. I'm seeing ~60Hz throughput when the node is run without anything else: Also, the magnetic field sensor is somehow now also working, although I think the scale factor is off. |
These results are actually comparable to a pure C++ implementation (https://github.com/bdholt1/ros2_bno055_sensor) so I suspect this might have to do with (1) bus speed limitations, or (2) IPC overhead. I'm leaning towards the former. |
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Worked out that we are bus limited -- it's either the i2c bus or the chip that is holding back the sampling frequency. Knowing this, I can get ~100Hz raw IMU and ~20Hz magnetometer with this PR, where I've separated our the publication into smaller i2c transactions. But I have to disable quaternion and gravitational vector publication: # For streaming raw inertial data.
Node(
package='bno055',
executable='bno055',
name='bno055_imu_node',
parameters=[
{ "ros_topic_prefix": "bno055/" },
{ "connection_type": "i2c" },
{ "i2c_bus": 0 },
{ "i2c_addr": 0x28 },
{ "imu_query_frequency": 100 },
{ "rot_query_frequency": 0 },
{ "gra_query_frequency": 0 },
{ "mag_query_frequency": 20 },
{ "tmp_query_frequency": 1 },
{ "cal_query_frequency": 1 },
{ "frame_id": "bno055" },
{ "operation_mode": 0x0C },
{ "placement_axis_remap": "P2" },
{ "acc_factor": 100.0 },
{ "mag_factor": 16000000.0 },
{ "gyr_factor": 900.0 },
{ "set_offsets" : False },
{ "offset_acc": [0xFFEC, 0x00A5, 0xFFE8] },
{ "offset_mag": [0xFFB4, 0xFE9E, 0x027D] },
{ "offset_gyr": [0x0002, 0xFFFF, 0xFFFF] }
],
output='screen'
),Here are my results on a Coral Dev Mini Board: |
@asymingt this might be something we can just add to the docs later so others know this as well for I2C. If you want to add it to this PR feel free, but also we can just add it in another PR later as well...not a big deal either way. |
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@flynneva I think I addressed your review comments. I added a couple of copyright headers to files that didn't have them. Hopefully that's OK. |
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@flynneva feel free to merge this when you're ready to add the changes. |
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@asymingt yes sorry! I am traveling for work this week (at CES) so I won't get to it this week but will make it a priority next week. |
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@asymingt again, thank you for the contribution! 🙏🏼 stuff like this is what makes the ROS / OSS community so great 👏🏼 |
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| try: | ||
| self.serialConnection.write(buf_out) | ||
| buf_in = bytearray(self.serialConnection.read()) |
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This line should be buf_in = bytearray(self.serialConnection.read(2)) since the UART protocol register write answers with two bytes (preferably 0xEE 0X01 - Write success) which is tested later in line 140. Additional reasoning: previous implementation in bno055/connectors/Connector.py line 126 and datasheet page 93.
This modifies the code to add I2C support for the BNO055 sensor using the
smbuslibrary for I2C access. It addsi2c_busandi2c_addrparameters to define the bus and address for the chip.TODO list:
ZeroDevisionErroron startupTested on a Google Coral Dev Mini board.
I do get two warnings about the first few readings being zero after initial configuration.
IMU data looks to not be garbage: