px4-firmware/apps/drivers/drv_pwm_output.h

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/**
 * @file PWM servo output interface.
 *
 * Servo values can be set with the PWM_SERVO_SET ioctl, by writing a
 * pwm_output_values structure to the device, or by publishing to the
 * output_pwm ObjDev.
 * Writing a value of 0 to a channel suppresses any output for that
 * channel.
 */

#pragma once

#include <stdint.h>
#include <sys/ioctl.h>

#include "drv_orb_dev.h"

__BEGIN_DECLS

/**
 * Path for the default PWM output device.
 *
 * Note that on systems with more than one PWM output path (e.g.
 * PX4FMU with PX4IO connected) there may be other devices that
 * respond to this protocol.
 */
#define PWM_OUTPUT_DEVICE_PATH	"/dev/pwm_output"

/**
 * Maximum number of PWM output channels in the system.
 */
#define PWM_OUTPUT_MAX_CHANNELS	16

/**
 * Servo output signal type, value is actual servo output pulse
 * width in microseconds.
 */
typedef uint16_t	servo_position_t;

/**
 * Servo output status structure.
 *
 * May be published to output_pwm, or written to a PWM output
 * device.
 */
struct pwm_output_values {
	/** desired servo update rate in Hz */
	uint32_t		update_rate;

	/** desired pulse widths for each of the supported channels */
	servo_position_t	values[PWM_OUTPUT_MAX_CHANNELS];
};

/*
 * ObjDev tag for PWM outputs.
 */
ORB_DECLARE(output_pwm);

/*
 * ioctl() definitions
 *
 * Note that ioctls and ObjDev updates should not be mixed, as the
 * behaviour of the system in this case is not defined.
 */
#define _PWM_SERVO_BASE		0x2700

/** arm all servo outputs handle by this driver */
#define PWM_SERVO_ARM		_IOC(_PWM_SERVO_BASE, 0)

/** disarm all servo outputs (stop generating pulses) */
#define PWM_SERVO_DISARM	_IOC(_PWM_SERVO_BASE, 1)

/** set a single servo to a specific value */
#define PWM_SERVO_SET(_servo)	_IOC(_PWM_SERVO_BASE, 0x20 + _servo)

/** get a single specific servo value */
#define PWM_SERVO_GET(_servo)	_IOC(_PWM_SERVO_BASE, 0x40 + _servo)


/*
 * Low-level PWM output interface.
 *
 * This is the low-level API to the platform-specific PWM driver.
 */

/**
 * Intialise the PWM servo outputs using the specified configuration.
 *
 * @param channel_mask	Bitmask of channels (LSB = channel 0) to enable.
 *			This allows some of the channels to remain configured
 *			as GPIOs or as another function.
 * @return		OK on success.
 */
__EXPORT extern int	up_pwm_servo_init(uint32_t channel_mask);

/**
 * De-initialise the PWM servo outputs.
 */
__EXPORT extern void	up_pwm_servo_deinit(void);

/**
 * Arm or disarm servo outputs.
 *
 * When disarmed, servos output no pulse.
 *
 * @bug This function should, but does not, guarantee that any pulse
 *      currently in progress is cleanly completed.
 *
 * @param armed		If true, outputs are armed; if false they
 *			are disarmed.
 */
__EXPORT extern void	up_pwm_servo_arm(bool armed);

/**
 * Set the servo update rate
 *
 * @param rate		The update rate in Hz to set.
 * @return		OK on success, -ERANGE if an unsupported update rate is set.
 */
__EXPORT extern int	up_pwm_servo_set_rate(unsigned rate);

/**
 * Set the current output value for a channel.
 *
 * @param channel	The channel to set.
 * @param value		The output pulse width in microseconds.
 */
__EXPORT extern int	up_pwm_servo_set(unsigned channel, servo_position_t value);

/**
 * Get the current output value for a channel.
 *
 * @param channel	The channel to read.
 * @return		The output pulse width in microseconds, or zero if
 *			outputs are not armed or not configured.
 */
__EXPORT extern servo_position_t up_pwm_servo_get(unsigned channel);

__END_DECLS