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3b32b89839
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@146 ebee16cc-31ac-478f-84a7-5cbb03baadba
109 lines
3.1 KiB
C
109 lines
3.1 KiB
C
/**
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******************************************************************************
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*
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* @file pios_delay.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
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* Parts by Thorsten Klose (tk@midibox.org) (tk@midibox.org)
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* @brief Delay Functions
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* - Provides a micro-second granular delay using a TIM
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* @see The GNU Public License (GPL) Version 3
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* @defgroup PIOS_DELAY Delay Functions
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* @{
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*
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*****************************************************************************/
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/*
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* This program 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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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/* Project Includes */
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#include "pios.h"
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/**
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* Initialises the Timer used by PIOS_DELAY functions<BR>
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* This is called from pios.c as part of the main() function
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* at system start up.
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* \return < 0 if initialisation failed
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*/
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int32_t PIOS_DELAY_Init(void)
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{
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/* Enable timer clock */
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if(PIOS_DELAY_TIMER_RCC == RCC_APB2Periph_TIM1 || PIOS_DELAY_TIMER_RCC == RCC_APB2Periph_TIM8) {
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RCC_APB2PeriphClockCmd(PIOS_DELAY_TIMER_RCC, ENABLE);
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} else {
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RCC_APB1PeriphClockCmd(PIOS_DELAY_TIMER_RCC, ENABLE);
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}
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/* Time base configuration */
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TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
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TIM_TimeBaseStructure.TIM_Period = 65535; // maximum value
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TIM_TimeBaseStructure.TIM_Prescaler = 72-1; // for 1 uS accuracy fixed to 72Mhz
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TIM_TimeBaseStructure.TIM_ClockDivision = 0;
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TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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TIM_TimeBaseInit(PIOS_DELAY_TIMER, &TIM_TimeBaseStructure);
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/* Enable counter */
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TIM_Cmd(PIOS_DELAY_TIMER, ENABLE);
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/* No error */
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return 0;
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}
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/**
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* Waits for a specific number of uS<BR>
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* Example:<BR>
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* \code
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* // Wait for 500 uS
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* PIOS_DELAY_Wait_uS(500);
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* \endcode
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* \param[in] uS delay (1..65535 microseconds)
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* \return < 0 on errors
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*/
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int32_t PIOS_DELAY_WaituS(uint16_t uS)
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{
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uint16_t start = PIOS_DELAY_TIMER->CNT;
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/* Note that this event works on 16bit counter wrap-arounds */
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while((uint16_t)(PIOS_DELAY_TIMER->CNT - start) <= uS);
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/* No error */
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return 0;
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}
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/**
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* Waits for a specific number of mS<BR>
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* Example:<BR>
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* \code
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* // Wait for 500 mS
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* PIOS_DELAY_Wait_mS(500);
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* \endcode
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* \param[in] mS delay (1..65535 milliseconds)
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* \return < 0 on errors
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*/
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int32_t PIOS_DELAY_WaitmS(uint16_t mS)
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{
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for(int i = 0; i < mS; i++) {
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PIOS_DELAY_WaituS(1000);
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}
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/* No error */
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return 0;
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}
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