icu.dox
4.68 KB
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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 ICU ICU Driver
* @brief Generic ICU Driver.
* @details This module implements a generic ICU (Input Capture Unit) driver.
* @pre In order to use the ICU driver the @p HAL_USE_ICU option
* must be enabled in @p halconf.h.
*
* @section icu_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).
* @if LATEX_PDF
* @dot
digraph example {
size="5, 7";
rankdir="LR";
node [shape=circle, fontname=Sans, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
edge [fontname=Sans, fontsize=8];
stop [label="ICU_STOP\nLow Power"];
uninit [label="ICU_UNINIT", style="bold"];
ready [label="ICU_READY\nClock Enabled"];
waiting [label="ICU_WAITING"];
active [label="ICU_ACTIVE"];
idle [label="ICU_IDLE"];
uninit -> stop [label=" icuInit()", constraint=false];
stop -> stop [label="\nicuStop()"];
stop -> ready [label="\nicuStart()"];
ready -> stop [label="\nicuStop()"];
ready -> ready [label="\nicuStart()\nicuDisable()"];
ready -> waiting [label="\nicuEnable()"];
waiting -> active [label="\nStart Front"];
waiting -> ready [label="\nicuDisable()"];
active -> idle [label="\nStop Front\n>width_cb<"];
active -> ready [label="\nicuDisable()\nicuDisableI()"];
idle -> active [label="\nStart Front\n>period_cb<"];
idle -> ready [label="\nicuDisable()\nicuDisableI()"];
}
* @enddot
* @else
* @dot
digraph example {
rankdir="LR";
node [shape=circle, fontname=Sans, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
edge [fontname=Sans, fontsize=8];
stop [label="ICU_STOP\nLow Power"];
uninit [label="ICU_UNINIT", style="bold"];
ready [label="ICU_READY\nClock Enabled"];
waiting [label="ICU_WAITING"];
active [label="ICU_ACTIVE"];
idle [label="ICU_IDLE"];
uninit -> stop [label=" icuInit()", constraint=false];
stop -> stop [label="\nicuStop()"];
stop -> ready [label="\nicuStart()"];
ready -> stop [label="\nicuStop()"];
ready -> ready [label="\nicuStart()\nicuDisable()"];
ready -> waiting [label="\nicuEnable()"];
waiting -> active [label="\nStart Front"];
waiting -> ready [label="\nicuDisable()"];
active -> idle [label="\nStop Front\n>width_cb<"];
active -> ready [label="\nicuDisable()\nicuDisableI()"];
idle -> active [label="\nStart Front\n>period_cb<"];
idle -> ready [label="\nicuDisable()\nicuDisableI()"];
}
* @enddot
* @endif
*
* @section icu_2 ICU Operations.
* This driver abstracts a generic Input Capture Unit composed of:
* - A clock prescaler.
* - A main up counter.
* - Two capture registers triggered by the rising and falling edges on
* the sampled input.
* .
* The ICU unit can be programmed to synchronize on the rising or falling
* edge of the sample input:
* - <b>ICU_INPUT_ACTIVE_HIGH</b>, a rising edge is the start signal.
* - <b>ICU_INPUT_ACTIVE_LOW</b>, a falling edge is the start signal.
* .
* After the activation the ICU unit can be in one of the following
* states at any time:
* - <b>ICU_WAITING</b>, waiting the first start signal.
* - <b>ICU_ACTIVE</b>, after a start signal.
* - <b>ICU_IDLE</b>, after a stop signal.
* .
* Callbacks are invoked when start or stop signals occur.
*
* @ingroup IO
*/