lidar_sf11 module

Parallax SF11-A/B/C Laser Rangefinder connected over i2c bus.

The update rate is 16 readings per second, so don't poll the lidar faster than 32Hz. In practice lidar_sf11_periodic() can run at most at freq=32. The i2c address can be reconfigured.

Example for airframe file

Add to your firmware section: This example contains all possible configuration options, not all of them are mandatory!

<module name="lidar_sf11">
  <configure name="LIDAR_SF11_I2C_DEV" value="i2c2" />
  <configure name="LIDAR_SF11_I2C_ADDR" value="0x50" />
  <configure name="USE_LIDAR_SF11_AGL" value="1" />
  <configure name="LIDAR_SF11_COMPENSATE_ROTATION" value="1" />
</module>

Module configuration options

Configure Options

• name: LIDAR_SF11_I2C_DEV value: i2c2
  Description: I2C device to use for lidar
• name: LIDAR_SF11_I2C_ADDR value: 0x50
  Description: default slave address of lidar
• name: USE_LIDAR_SF11_AGL value: 1
  Description: use this lidar for AGL measurements. On by deafult
• name: LIDAR_SF11_COMPENSATE_ROTATION value: 1
  Description: compensate AGL measurements for body rotation

Module functions

Init Functions

These initialization functions are called once on startup.

• lidar_sf11_init()

Event Functions

These event functions are called in each cycle of the module event loop.

• lidar_sf11_event()

Periodic Functions

These functions are called periodically at the specified frequency from the module periodic loop.

• lidar_sf11_downlink()
  • Frequency in Hz: 4
  • Autorun: FALSE
    Periodic function is started by user command.
• lidar_sf11_periodic()
  • Frequency in Hz: 32
  • Autorun: LOCK
    Periodic function automatically starts after init and can't be stopped.

Files

Header Files

The following headers are automatically included in modules.h

• lidar_sf11.h

Source Files

• modules/lidar/lidar_sf11.c

Raw lidar_sf11.xml file:

<!DOCTYPE module SYSTEM "module.dtd">

<module name="lidar_sf11" dir="lidar">
  <doc>
    <description>
      Parallax SF11-A/B/C Laser Rangefinder connected over i2c bus.
      The update rate is 16 readings per second, so don't poll the lidar faster than 32Hz.
      In practice lidar_sf11_periodic() can run at most at freq=32.
      The i2c address can be reconfigured.
    </description>
    <configure name="LIDAR_SF11_I2C_DEV" value="i2c2" description="I2C device to use for lidar"/>
    <configure name="LIDAR_SF11_I2C_ADDR" value="0x50" description="default slave address of lidar"/>
    <configure name="USE_LIDAR_SF11_AGL" value="1" description="use this lidar for AGL measurements. On by deafult"/>
    <configure name="LIDAR_SF11_COMPENSATE_ROTATION" value="1" description="compensate AGL measurements for body rotation"/>
  </doc>

  <settings>
    <dl_settings NAME="Lidar SF11">
      <dl_settings NAME="Lidar">
        <dl_setting MAX="1" MIN="0" STEP="1" VAR="lidar_sf11.compensate_rotation" shortname="derotate_agl"/>
        <dl_setting MAX="1" MIN="0" STEP="1" VAR="lidar_sf11.update_agl" shortname="update_agl"/>
      </dl_settings>
    </dl_settings>
  </settings>

  <header>
    <file name="lidar_sf11.h"/>
  </header>
  <init fun="lidar_sf11_init()"/>
  <periodic fun="lidar_sf11_downlink()" freq="4" autorun="FALSE"/> <!-- for debug -->
  <periodic fun="lidar_sf11_periodic()" freq="32"/> <!-- poll data, since we have 2 states in the state machine, divide the frequency
   by 2 to get the actual number of readings per second. For example 32Hz = 16 range readings, which is the maximum (per the datasheet) -->
  <event fun="lidar_sf11_event()"/>
  <makefile>
    <configure name="LIDAR_SF11_I2C_DEV" default="i2c1" case="lower|upper"/>
    <configure name="LIDAR_SF11_I2C_ADDR" default="0x50"/>
    <configure name="USE_LIDAR_SF11_AGL" default="1"/>
    <configure name="LIDAR_SF11_COMPENSATE_ROTATION" default="1"/>
    <define name="LIDAR_SF11_I2C_DEV" value="$(LIDAR_SF11_I2C_DEV_LOWER)"/>
    <define name="USE_$(LIDAR_SF11_I2C_DEV_UPPER)"/>
    <define name="LIDAR_SF11_I2C_ADDR" value="$(LIDAR_SF11_I2C_ADDR)"/>
    <define name="USE_LIDAR_SF11_AGL" value="$(USE_LIDAR_SF11_AGL)"/>
    <define name="LIDAR_SF11_COMPENSATE_ROTATION" value="$(LIDAR_SF11_COMPENSATE_ROTATION)"/>
    <file name="lidar_sf11.c"/>
  </makefile>
  <makefile target="nps">
    <define name="USE_SONAR" value="1"/><!-- in NPS use a virtual sonar to simulate lidar measurements -->
  </makefile>
</module>