75 lines
3 KiB
Plaintext
75 lines
3 KiB
Plaintext
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/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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* @defgroup GPT GPT Driver
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* @brief Generic GPT Driver.
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* @details This module implements a generic GPT (General Purpose Timer)
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* driver. The timer can be programmed in order to trigger callbacks
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* after a specified time period or continuously with a specified
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* interval.
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* @pre In order to use the GPT driver the @p HAL_USE_GPT option
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* must be enabled in @p halconf.h.
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*
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* @section gpt_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",
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width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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stop [label="GPT_STOP\nLow Power"];
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uninit [label="GPT_UNINIT", style="bold"];
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ready [label="GPT_READY\nClock Enabled"];
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continuous [label="GPT_CONT..S\nContinuous\nMode"];
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oneshot [label="GPT_ONESHOT\nOne Shot\nMode"];
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uninit -> stop [label=" gptInit()", constraint=false];
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stop -> stop [label="\ngptStop()"];
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stop -> ready [label="\ngptStart()"];
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ready -> stop [label="\ngptStop()"];
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ready -> ready [label="\ngptStart()"];
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ready -> continuous [label="\ngptStartContinuous()"];
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continuous -> ready [label="\ngptStopTimer()"];
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continuous -> continuous [label=">callback<"];
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ready -> oneshot [label="\ngptStartOneShot()\ngptPolledDelay()"];
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oneshot -> ready [label="\n>callback<\nor\nDelay Over"];
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}
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* @enddot
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*
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* @section gpt_2 GPT Operations.
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* This driver abstracts a generic 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. A callback is invoked when this happens.
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* .
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* The timer can operate in three different modes:
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* - <b>Continuous Mode</b>, a periodic callback is invoked until the driver
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* is explicitly stopped.
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* - <b>One Shot Mode</b>, a callback is invoked after the programmed period
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* and then the timer automatically stops.
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* - <b>Delay Mode</b>, the timer is used for inserting a brief delay into
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* the execution flow, no callback is invoked in this mode.
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* .
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* @ingroup HAL_NORMAL_DRIVERS
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*/
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