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--- eeros_architecture:hal:feature_functions [2017/04/30 09:52] – created graf
+++ eeros_architecture:hal:feature_functions [2021/05/16 09:33] (current) – [List of Feature Function for Hardware Wrapper Libraries] ursgraf
@@ Line 1: / Line 1: @@
 ====== Feature Functions ======
+All inputs and outputs of the HAL have a common set of properties and functions for reading or writing them. Some hardware channels have specific properties not common to other channels, e.g. a pulse width modulated output needs to be assigned its base frequency. Another example would be a digital to analog converter which has a calibration function which needs to be called upon request. \\
+Feature functions are functions which are specific to a HAL object. They can be called by a user with
+<code cpp>
+  void callOutputFeature(OutputInterface *obj, std::string featureName, ArgTypesOut... args);
+  void callInputFeature(InputInterface *obj, std::string featureName, ArgTypesIn... args);
+</code>
+The parameter are as follows:
+  - OutputInterface / InputInterface: the HAL object
+  - featureName: name of the function as defined in the appropriate hardware wrapper library, see [[eeros_architecture:hal:hardware_libraries|]].
+  - args: arguments to this function
+The following example shows how to set the frequency of a pulse width modulated output. This
+is usually done just once. After this you can release the object.
+<code cpp>
+  HAL& hal = HAL::instance();
+  eeros::hal::Output<double>* pwm = hal.getScalableOutput("pwm1");
+  hal.callOutputFeature(pwm, "setPwmFrequency", 100.0);
+  hal.releaseOutput("pwm1");
+</code>
+===== Accessing Feature Functions from the Control System =====
+The control system defines a peripheral output objects which is connected to our HAL object. The control system will usually periodically write to this output and set the duty cycle.
+However, if you wish to change the frequency of the signal you must again use the feature function as follows:
+<code cpp>
+  PeripheralOutput<double> motorSpeed("pwm1");
+  motorSpeed.callOutputFeature("setPwmFrequency", 200.0);
+</code>
+===== List of Feature Function for Hardware Wrapper Libraries =====
+^library^type^function^Parameter^Description^
+|bbblue-eeros|AnalogOut|freeSpin|channel|Puts a motor into a zero-throttle state allowing it to spin freely. Motor channel (1-4) or 0 for all channels. Make sure, that the peripheral output driving the motor does not run, else the set function will reenable the H-bridge.|
+|:::|:::|brake|channel|Connects the motor terminal pairs together which makes the motor fight against its own back EMF turning it into a brake resisting rotation. Motor channel (1-4) or 0 for all channels. Make sure, that the peripheral output driving the motor does not run, else the set function will reenable the H-bridge.|
+|:::|Fqd|resetFqd| |Sets the encoder position to zero. This can be useful for homing.|
+|:::|:::|setFqdPos|position|Sets the encoder position to a given value. This can be useful for homing.|
+|flink-eeros|Fqd|resetFqd| |Sets the encoder position to zero. This can be useful for homing.|
+|:::|Pwm|setPwmFrequency|frequency|Sets the pwm frequency (Hz).|
+|:::|:::|setPwmDutyCycle|duty cycle|Sets the pwm duty cycle (0.0 .. 1.0).|
+|:::|Watchdog|resetWatchdog| |Resets the watchdog.|
+|:::|:::|setWatchdogTimeout|timeout|Sets the watchdog timeout (s).|