Angle of Attack sensor using PWM input

Driver for a PWM based angle of attack sensor A second sensor can be defined for the sideslip angle It is assumed that both sensors are the same, only sensitivity, offset and direction can differ.

Sensor example: US DIGITAL MA3-P12-125-B

Example for airframe file

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

<module name="AOA_pwm">
  b'<define name="AOA_SENS" value="(2*3.14)/AOA_PWM_PERIOD" />\n    '
  b'<define name="AOA_OFFSET" value="0." />\n    '
  b'<define name="AOA_ANGLE_OFFSET" value="3.14" />\n    '
  b'<define name="AOA_REVERSE" value="TRUE|FALSE" />\n    '
  b'<define name="AOA_PWM_PERIOD" value="4096" />\n    '
  b'<define name="AOA_PWM_OFFSET" value="1" />\n    '
  b'<define name="SEND_AOA" value="TRUE|FALSE" />\n    '
  b'<define name="LOG_AOA" value="TRUE|FALSE" />\n    '
  b'<define name="SSA_SENS" value="(2*3.14)/AOA_PWM_PERIOD" />\n    '
  b'<define name="SSA_OFFSET" value="0." />\n    '
  b'<define name="SSA_REVERSE" value="TRUE|FALSE" />\n  '
  b'<configure name="AOA_PWM_CHANNEL" value="PWM_INPUTX" />\n    '
  b'<configure name="SSA_PWM_CHANNEL" value="PWM_INPUTX" />\n    '
</module>

Module configuration options

Configure Options

name: AOA_PWM_CHANNEL value: PWM_INPUTX
Description: Select PWM input channel for AOA sensor
name: SSA_PWM_CHANNEL value: PWM_INPUTX
Description: Select PWM input channel for Sideslip sensor (optional)

Define Options

name: AOA_SENS value: (2*3.14)/AOA_PWM_PERIOD
Description: sensor sensitivity
name: AOA_OFFSET value: 0.
Description: offset in radian that can be set from settings
name: AOA_ANGLE_OFFSET value: 3.14
Description: global offset in radian corresponding to the sensor mounting (default: 3.14)
name: AOA_REVERSE value: TRUE|FALSE
Description: set to TRUE to reverse rotation direction
name: AOA_PWM_PERIOD value: 4096
Description: period in microsec (e.g. 4096 for 12 bits sensor)
name: AOA_PWM_OFFSET value: 1
Description: initial offset on the raw pwm signal if needed (default: 1usec)
name: SEND_AOA value: TRUE|FALSE
Description: enable telemetry report (default: TRUE)
name: LOG_AOA value: TRUE|FALSE
Description: enable logging on SD card (default: FALSE)
name: SSA_SENS value: (2*3.14)/AOA_PWM_PERIOD
Description: sensor sensitivity
name: SSA_OFFSET value: 0.
Description: offset in radian that can be set from settings
name: SSA_REVERSE value: TRUE|FALSE
Description: set to TRUE to reverse rotation direction

Module functions

Init Functions

These initialization functions are called once on startup.

aoa_pwm_init()

Periodic Functions

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

aoa_pwm_update()
- Frequency in Hz: 20
- 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

aoa_pwm.h

Source Files

modules/sensors/aoa_pwm.c

Raw AOA_pwm.xml file:

<!DOCTYPE module SYSTEM "module.dtd">
 
<module name="AOA_pwm" dir="sensors" task="sensors">
  <doc>
    <description>
      Angle of Attack sensor using PWM input
 
      Driver for a PWM based angle of attack sensor
      A second sensor can be defined for the sideslip angle
      It is assumed that both sensors are the same, only sensitivity, offset and direction can differ.
 
      Sensor example: US DIGITAL MA3-P12-125-B
    </description>
    <configure name="AOA_PWM_CHANNEL" value="PWM_INPUTX" description="Select PWM input channel for AOA sensor"/>
    <define name="AOA_SENS" value="(2*3.14)/AOA_PWM_PERIOD" description="sensor sensitivity"/>
    <define name="AOA_OFFSET" value="0."  description="offset in radian that can be set from settings"/>
    <define name="AOA_ANGLE_OFFSET" value="3.14"  description="global offset in radian corresponding to the sensor mounting (default: 3.14)"/>
    <define name="AOA_REVERSE" value="TRUE|FALSE" description="set to TRUE to reverse rotation direction"/>
    <define name="AOA_PWM_PERIOD" value="4096" description="period in microsec (e.g. 4096 for 12 bits sensor)"/>
    <define name="AOA_PWM_OFFSET" value="1" description="initial offset on the raw pwm signal if needed (default: 1usec)"/>
    <define name="SEND_AOA" value="TRUE|FALSE" description="enable telemetry report (default: TRUE)"/>
    <define name="LOG_AOA" value="TRUE|FALSE" description="enable logging on SD card (default: FALSE)"/>
    <configure name="SSA_PWM_CHANNEL" value="PWM_INPUTX" description="Select PWM input channel for Sideslip sensor (optional)"/>
    <define name="SSA_SENS" value="(2*3.14)/AOA_PWM_PERIOD" description="sensor sensitivity"/>
    <define name="SSA_OFFSET" value="0."  description="offset in radian that can be set from settings"/>
    <define name="SSA_REVERSE" value="TRUE|FALSE" description="set to TRUE to reverse rotation direction"/>
  </doc>
  <settings>
    <dl_settings>
      <dl_settings NAME="AOA">
        <dl_setting MAX="1" MIN="0" STEP="1" VAR="aoa_send_type" shortname="send type" module="modules/sensors/aoa_pwm" values="AOA|SIDESLIP"/>
        <dl_setting MAX="180" MIN="-180" STEP="0.1" VAR="aoa_pwm.offset" shortname="AOA_offset" module="modules/sensors/aoa_pwm" param="AOA_OFFSET" unit="rad" alt_unit="deg"/>
        <dl_setting MAX="0.95" MIN="0" STEP="0.001" VAR="aoa_pwm.filter" shortname="AOA_filter" module="modules/sensors/aoa_pwm" param="AOA_FILTER"/>
        <dl_setting MAX="180" MIN="-180" STEP="0.1" VAR="ssa_pwm.offset" shortname="SSA_offset" module="modules/sensors/aoa_pwm" param="SSA_OFFSET" unit="rad" alt_unit="deg"/>
        <dl_setting MAX="0.95" MIN="0" STEP="0.001" VAR="ssa_pwm.filter" shortname="SSA_filter" module="modules/sensors/aoa_pwm" param="SSA_FILTER"/>
      </dl_settings>
    </dl_settings>
  </settings>
 
  <dep>
    <depends>pwm_meas</depends>
  </dep>
  <header>
    <file name="aoa_pwm.h" />
  </header>
 
  <init fun="aoa_pwm_init()" />
  <periodic fun="aoa_pwm_update()" freq="20" />
 
  <makefile target="ap">
    <file name="aoa_pwm.c" />
    <define name="AOA_PWM_CHANNEL" value="$(AOA_PWM_CHANNEL)" cond="ifdef AOA_PWM_CHANNEL" />
    <define name="$(AOA_PWM_CHANNEL)_TICKS_PER_USEC" value="1" />
    <define name="USE_$(AOA_PWM_CHANNEL)" value="PWM_PULSE_TYPE_ACTIVE_LOW" />
    <define name="SSA_PWM_CHANNEL" value="$(SSA_PWM_CHANNEL)" cond="ifdef SSA_PWM_CHANNEL" />
    <define name="$(SSA_PWM_CHANNEL)_TICKS_PER_USEC" value="1" cond="ifdef SSA_PWM_CHANNEL" />
    <define name="USE_$(SSA_PWM_CHANNEL)" value="PWM_PULSE_TYPE_ACTIVE_LOW" cond="ifdef SSA_PWM_CHANNEL" />
    <define name="USE_SIDESLIP" cond="ifdef SSA_PWM_CHANNEL" />
  </makefile>
</module>