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https://github.com/PX4/PX4-Autopilot.git
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Add basic support for pulse count in the PWM interface
git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4285 7fd9a85b-ad96-42d3-883c-3090e2eb8679
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patacongo
@@ -1,7 +1,7 @@
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/****************************************************************************
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* include/nuttx/pwm.h
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*
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* Copyright (C) 2011 Gregory Nutt. All rights reserved.
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* Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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@@ -66,6 +66,18 @@
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/****************************************************************************
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* Pre-Processor Definitions
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****************************************************************************/
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/* Configuration ************************************************************/
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/* CONFIG_PWM - Enables because PWM driver support
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* CONFIG_PWM_PULSECOUNT - Some hardware will support generation of a fixed
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* number of pulses. This might be used, for example to support a stepper
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* motor. If the hardware will support a fixed pulse count, then this
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* configuration should be set to enable the capability.
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* CONFIG_DEBUG_PWM - If enabled (with CONFIG_DEBUG and, optionally,
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* CONFIG_DEBUG_VERBOSE), this will generate output that can be use dto
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* debug the PWM driver.
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*/
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/* IOCTL Commands ***********************************************************/
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/* The PWM module uses a standard character driver framework. However, since
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* the PWM driver is a devices control interface and not a data transfer
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* interface, the majority of the functionality is implemented in driver
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@@ -75,7 +87,8 @@
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* output. This command will neither start nor stop the pulsed output.
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* It will either setup the configuration that will be used when the
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* output is started; or it will change the characteristics of the pulsed
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* output on the fly if the timer is already started.
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* output on the fly if the timer is already started. This command will
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* set the PWM characteristics and return immediately.
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*
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* ioctl argument: A read-only reference to struct pwm_info_s that provides
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* the characteristics of the pulsed output.
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@@ -87,11 +100,16 @@
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* characteristics of the pulsed output.
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*
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* PWMIOC_START - Start the pulsed output. The PWMIOC_SETCHARACTERISTICS
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* command must have previously been sent.
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* command must have previously been sent. If CONFIG_PWM_PULSECOUNT is
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* defined and the pulse count was configured to a non-zero value, then
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* this ioctl call will, by default, block until the programmed pulse count
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* completes. That default blocking behavior can be overridden by using
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* the O_NONBLOCK flag when the PWM driver is opened.
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*
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* ioctl argument: None
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*
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* PWMIOC_STOP - Stop the pulsed output.
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* PWMIOC_STOP - Stop the pulsed output. This command will stop the PWM
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* and return immediately.
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*
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* ioctl argument: None
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*/
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@@ -109,7 +127,13 @@
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struct pwm_info_s
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{
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uint32_t frequency; /* Frequency of the pulse train */
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ub16_t duty; /* Duty of the pulse train, "1" to "0" duration */
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ub16_t duty; /* Duty of the pulse train, "1"-to-"0" duration.
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* Maximum: 65535/65536 (0x0000ffff)
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* Minimum: 1/65536 (0x00000001) */
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#ifdef CONFIG_PWM_PULSECOUNT
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uint32_t count; /* The number of pulse to generate. 0 means to
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* generate an indefinite number of pulses */
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#endif
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};
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/* This structure is a set a callback functions used to call from the upper-
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@@ -134,9 +158,19 @@ struct pwm_ops_s
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CODE int (*shutdown)(FAR struct pwm_lowerhalf_s *dev);
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/* (Re-)initialize the timer resources and start the pulsed output */
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/* (Re-)initialize the timer resources and start the pulsed output. The
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* start method should return an error if it cannot start the timer with
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* the given parameter (frequency, duty, or optionally pulse count)
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*/
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CODE int (*start)(FAR struct pwm_lowerhalf_s *dev, FAR const struct pwm_info_s *info);
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#ifdef CONFIG_PWM_PULSECOUNT
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CODE int (*start)(FAR struct pwm_lowerhalf_s *dev,
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FAR const struct pwm_info_s *info,
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FAR void *handle);
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#else
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CODE int (*start)(FAR struct pwm_lowerhalf_s *dev,
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FAR const struct pwm_info_s *info);
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#endif
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/* Stop the pulsed output and reset the timer resources*/
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@@ -144,7 +178,8 @@ struct pwm_ops_s
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/* Lower-half logic may support platform-specific ioctl commands */
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CODE int (*ioctl)(FAR struct pwm_lowerhalf_s *dev, int cmd, unsigned long arg);
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CODE int (*ioctl)(FAR struct pwm_lowerhalf_s *dev,
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int cmd, unsigned long arg);
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};
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/* This structure is the generic form of state structure used by lower half
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@@ -217,6 +252,47 @@ extern "C" {
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int pwm_register(FAR const char *path, FAR struct pwm_lowerhalf_s *dev);
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/****************************************************************************
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* Name: pwm_expired
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*
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* Description:
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* If CONFIG_PWM_PULSECOUNT is defined and the pulse count was configured
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* to a non-zero value, then the "upper half" driver will wait for the
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* pulse count to expire. The sequence of expected events is as follows:
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*
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* 1. The upper half driver calls the start method, providing the lower
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* half driver with the pulse train characteristics. If a fixed
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* number of pulses is required, the 'count' value will be nonzero.
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* 2. The lower half driver's start() methoc must verify that it can
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* support the request pulse train (frequency, duty, AND pulse count).
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* It it cannot, it should return an error. If the pulse count is
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* non-zero, it should set up the hardware for that number of pulses
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* and return success. NOTE: That is CONFIG_PWM_PULSECOUNT is
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* defined, the start() method receives an additional parameter
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* that must be used in this callback.
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* 3. When the start() method returns success, the upper half driver
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* will "sleep" until the pwm_expired method is called.
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* 4. When the lower half detects that the pulse count has expired
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* (probably through an interrupt), it must call the pwm_expired
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* interface using the handle that was previously passed to the
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* start() method
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*
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* Input parameters:
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* handle - This is the handle that was provided to the lower-half
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* start() method.
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*
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* Returned Value:
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* None
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*
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* Assumptions:
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* This function may be called from an interrupt handler.
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*
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****************************************************************************/
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#ifdef CONFIG_PWM_PULSECOUNT
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EXTERN void pwm_expired(FAR void *handle);
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#endif
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/****************************************************************************
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* Platform-Independent "Lower-Half" PWM Driver Interfaces
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****************************************************************************/
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