Implement communication to IMU

[whymarrh]

The IMU communication is via I²C

[whymarrh]

@EasternEdgeRobotics/developers this is up for grabs is anyone wants to take it

[cal-pratt]

@whymarrh Currently working on this item.

The best library to use seems to be:

• http://pi4j.com/

Sample code of interest:

• https://blogs.oracle.com/acaicedo/entry/some_samples_using_gpio_and

[whymarrh]

Though they'll share the underlying communication protocol, is this different from the thruster stuff (#9)?

[cal-pratt]

The thrusters are run through an I2C interface.
The design decision to move i2c functions to the rasprime requires that the arduino communication (in system-manager branch) be translated to java.

I was considering using PI4J for this.

[cal-pratt]

Ah, I completely misread this. After basic code for i2c communication is added, the IMU portion of the task can be handed off.

[cal-pratt]

Current status of AltIMU-10 v3 components:

• L3GD20H Gyroscope datasheet
  • Define register addresses Register lookup for L3GD20H Gyro #65
  • Define Angular Velocity values L3GD20H Gyro and Immutable/ Mutable Angular Velocity Value Pair #70
  • Create L3gGyro hardware interface L3GD20H Gyro and Immutable/ Mutable Angular Velocity Value Pair #70 - in progress
  • Test on hardware
• LSM303D Accelerometer & magnetometer datasheet
  • Define register addresses - in progress
  • Define Acceleration values - in progress
  • Define Magnetic Filed values (compass) - in progress
  • Determine startup procedures
  • Create LSM303D hardware interface
  • Test on hardware
• LPS331AP Barometer datasheet
  • Define register addresses
  • Define Pressure values
  • Determine startup procedures
  • Create Barometer hardware interface
  • Test on hardware
• AltIMU GUI
  • Create Angular Velocity view
  • Create Acceleration view
  • Create Magnetic Filed view (compass)
  • Create Pressure view

---

Device details:

Sensor	Address low	Address high (default)
L3GD20H gyroscope	1101010b	1101011b
LSM303D accelerometer & magnetometer	0011110b	0011111b
LPS331AP barometer	1011100b	1011101b

Output format (I²C):

• Gyro: one 16-bit reading per axis
• Accelerometer: one 16-bit reading per axis
• Magnetometer: one 16-bit reading per axis
• Barometer: 24-bit pressure reading (4096 LSb/mbar)

Sensitivity range:

• Gyro: ±245, ±500, or ±2000°/s
• Accelerometer: ±2, ±4, ±6, ±8, or ±16 g
• Magnetometer: ±2, ±4, ±8, or ±12 gauss
• Barometer: 260 mbar to 1260 mbar (26 kPa to 126 kPa)

[cal-pratt]

Note that the AltIMU devices use predefined I²C addresses. We're going to use the grounded (low) addresses, however, we should avoid re-using any of these addresses to avoid future conflicts.

Reserved Addresses: 0x6A, 0x6B, 0x1E, 0x1F, 0x5C, 0x5D

[whymarrh]

The amount of time required to make IMU output useful to us is greater than the amount of time we have.