kopia lustrzana https://github.com/OpenRTX/OpenRTX
73 wiersze
2.6 KiB
C
73 wiersze
2.6 KiB
C
/***************************************************************************
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* Copyright (C) 2022 - 2025 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN *
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* Frederik Saraci IU2NRO *
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* Silvano Seva IU2KWO *
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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, *
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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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* *
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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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#ifndef TIMERS_H
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#define TIMERS_H
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#include <stdint.h>
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#include <stm32f4xx.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Configure prescaler and auto-reload register of a timer peripheral for a
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* given update frequency.
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*
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* @param tim: timer peripheral to be configured.
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* @param updFreq: desidered update frequency, in Hz.
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* @param busFreq: frequency of the APB bus the timer is attached to, in Hz.
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* @return effective timer update frequency, in Hz.
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*/
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inline uint32_t tim_setUpdateFreqency(TIM_TypeDef *tim, uint32_t updFreq,
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uint32_t busFreq)
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{
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/*
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* Timer update frequency is given by:
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* Fupd = (Fbus / prescaler) / autoreload
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*
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* First of all we fix the prescaler to 1 and compute the autoreload: if
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* the result is greater than the maximum autoreload value, we proceed
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* iteratively.
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*/
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uint32_t psc = 1;
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uint32_t arr = busFreq/updFreq;
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while(arr >= 0xFFFF)
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{
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psc += 1;
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arr = (busFreq / psc) / updFreq;
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}
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/* Values put in registers have to be decremented by one, see RM */
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tim->PSC = psc - 1;
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tim->ARR = arr - 1;
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return (busFreq/psc)/arr;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* USART3_H */
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