gpt.dox
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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @defgroup GPT GPT Driver
* @brief Generic GPT Driver.
* @details This module implements a generic GPT (General Purpose Timer)
* driver. The timer can be programmed in order to trigger callbacks
* after a specified time period or continuously with a specified
* interval.
* @pre In order to use the GPT driver the @p HAL_USE_GPT option
* must be enabled in @p halconf.h.
*
* @section gpt_1 Driver State Machine
* The driver implements a state machine internally, not all the driver
* functionalities can be used in any moment, any transition not explicitly
* shown in the following diagram has to be considered an error and shall
* be captured by an assertion (if enabled).
* @dot
digraph example {
rankdir="LR";
node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true",
width="0.9", height="0.9"];
edge [fontname=Helvetica, fontsize=8];
stop [label="GPT_STOP\nLow Power"];
uninit [label="GPT_UNINIT", style="bold"];
ready [label="GPT_READY\nClock Enabled"];
continuous [label="GPT_CONT..S\nContinuous\nMode"];
oneshot [label="GPT_ONESHOT\nOne Shot\nMode"];
uninit -> stop [label=" gptInit()", constraint=false];
stop -> stop [label="\ngptStop()"];
stop -> ready [label="\ngptStart()"];
ready -> stop [label="\ngptStop()"];
ready -> ready [label="\ngptStart()"];
ready -> continuous [label="\ngptStartContinuous()"];
continuous -> ready [label="\ngptStopTimer()"];
continuous -> continuous [label=">callback<"];
ready -> oneshot [label="\ngptStartOneShot()\ngptPolledDelay()"];
oneshot -> ready [label="\n>callback<\nor\nDelay Over"];
}
* @enddot
*
* @section gpt_2 GPT Operations.
* This driver abstracts a generic timer composed of:
* - A clock prescaler.
* - A main up counter.
* - A comparator register that resets the main counter to zero when the limit
* is reached. A callback is invoked when this happens.
* .
* The timer can operate in three different modes:
* - <b>Continuous Mode</b>, a periodic callback is invoked until the driver
* is explicitly stopped.
* - <b>One Shot Mode</b>, a callback is invoked after the programmed period
* and then the timer automatically stops.
* - <b>Delay Mode</b>, the timer is used for inserting a brief delay into
* the execution flow, no callback is invoked in this mode.
* .
* @ingroup IO
*/