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drivers: added servo motor driver

dev/timer
Hauke Petersen 9 years ago
parent
commit
e2a8bcb832
  1. 3
      drivers/Makefile
  2. 86
      drivers/include/servo.h
  3. 3
      drivers/servo/Makefile
  4. 46
      drivers/servo/servo.c

3
drivers/Makefile

@ -34,5 +34,8 @@ endif
ifneq (,$(filter rgbled,$(USEMODULE)))
DIRS += rgbled
endif
ifneq (,$(filter servo,$(USEMODULE)))
DIRS += servo
endif
include $(RIOTBASE)/Makefile.base

86
drivers/include/servo.h

@ -0,0 +1,86 @@
/*
* Copyright (C) 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @defgroup driver_servo Servo Motor Driver
* @ingroup drivers
* @brief High-level driver for servo motors
* @{
*
* @file
* @brief High-level driver for easy handling of servo motors
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*/
#ifndef __SERVO_H
#define __SERVO_H
#include "periph/pwm.h"
/**
* @name Descriptor struct for a servo
*/
typedef struct {
pwm_t device; /**< the PWM device driving the servo */
int channel; /**< the channel the servo is connected to */
unsigned int min; /**< minimum pulse width, in us */
unsigned int max; /**< maximum pulse width, in us */
} servo_t;
/**
* @brief Initialize a servo motor by assigning it a PWM device and channel
*
* Digital servos are controlled by regular pulses sent to them. The width
* of a pulse determines the position of the servo. A pulse width of 1.5ms
* puts the servo in the center position, a pulse width of about 1.0ms and
* about 2.0ms put the servo to the maximum angles. These values can however
* differ slightly from servo to servo, so the min and max values are
* parameterized in the init function.
*
* The servo is initialized with fixed PWM values:
* - frequency: 100Hz (10ms interval)
* - resolution: 10000 (1000 steps per ms)
*
* Caution: When initializing a servo, the PWM device will be reconfigured to
* new frequency/resolution values. It is however fine to use multiple servos
* with the same PWM device, just on different channels.
*
* @param[out] dev struct describing the servo
* @param[in] pwm the PWM device the servo is connected to
* @param[in] pwm_channel the PWM channel the servo is connected to
* @param[in] min minimum pulse width in us
* @param[in] max maximum pulse width in us
*
* @return 0 on success
* @return <0 on error
*/
int servo_init(servo_t *dev, pwm_t pwm, int pwm_channel, unsigned int min, unsigned int max);
/**
* @brief Set the servo motor to a specified position
*
* The position of the servo is specified in the pulse width that controls the
* servo. A value of 1500 means a pulse width of 1.5 ms, which is the center
* position on most servos.
*
* In case pos is larger/smaller then the max/min values, pos will be set to
* these values.
*
* @param[in] dev the servo to set
* @param[in] pos the position to set the servo in us
*
* @return 0 on success
* @return -1 on invalid configured channel
* @return -2 on invalid position
*/
int servo_set(servo_t *dev, unsigned int pos);
#endif /* __SERVO_H */
/** @} */

3
drivers/servo/Makefile

@ -0,0 +1,3 @@
MODULE = servo
include $(RIOTBASE)/Makefile.base

46
drivers/servo/servo.c

@ -0,0 +1,46 @@
/*
* Copyright (C) 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup driver_servo
* @{
*
* @file
* @brief Servo motor driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "servo.h"
#include "periph/pwm.h"
#define FREQUENCY (100U)
#define RESOLUTION (10000U)
int servo_init(servo_t *dev, pwm_t pwm, int pwm_channel, unsigned int min, unsigned int max)
{
dev->device = pwm;
dev->channel = pwm_channel;
dev->min = min;
dev->max = max;
return pwm_init(dev->device, PWM_LEFT, FREQUENCY, RESOLUTION);
}
int servo_set(servo_t *dev, unsigned int pos)
{
if (pos > dev->max) {
pos = dev->max;
}
else (pos < dev->min) {
pos = dev->min;
}
return pwm_set(dev->device, dev->channel, pos);
}
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