70 lines
2.8 KiB
Plaintext
70 lines
2.8 KiB
Plaintext
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
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2011 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @defgroup PWM PWM Driver
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* @brief Generic PWM Driver.
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* @details This module implements a generic PWM (Pulse Width Modulation)
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* driver.
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* @pre In order to use the PWM driver the @p HAL_USE_PWM option
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* must be enabled in @p halconf.h.
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*
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* @section pwm_1 Driver State Machine
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* The driver implements a state machine internally, not all the driver
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* functionalities can be used in any moment, any transition not explicitly
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* shown in the following diagram has to be considered an error and shall
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* be captured by an assertion (if enabled).
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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uninit [label="PWM_UNINIT", style="bold"];
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stop [label="PWM_STOP\nLow Power"];
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ready [label="PWM_READY\nClock Enabled"];
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uninit -> stop [label="pwmInit()"];
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stop -> stop [label="pwmStop()"];
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stop -> ready [label="pwmStart()"];
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ready -> stop [label="pwmStop()"];
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ready -> ready [label="pwmEnableChannel()\npwmDisableChannel()"];
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}
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* @enddot
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*
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* @section pwm_2 PWM Operations.
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* This driver abstracts a generic PWM timer composed of:
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* - A clock prescaler.
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* - A main up counter.
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* - A comparator register that resets the main counter to zero when the limit
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* is reached. An optional callback can be generated when this happens.
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* - An array of @p PWM_CHANNELS PWM channels, each channel has an output,
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* a comparator and is able to invoke an optional callback when a comparator
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* match with the main counter happens.
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* .
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* A PWM channel output can be in two different states:
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* - <b>IDLE</b>, when the channel is disabled or after a match occurred.
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* - <b>ACTIVE</b>, when the channel is enabled and a match didn't occur yet
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* in the current PWM cycle.
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* .
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* Note that the two states can be associated to both logical zero or one in
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* the @p PWMChannelConfig structure.
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*
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* @ingroup IO
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*/
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