86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2, as
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* published by the Free Software Foundation.
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*
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* this software 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 software. If not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Daniele Lacamera
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*
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*
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*/
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#include <stdint.h>
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#include "system.h"
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#define TIM2_BASE (0x40000000)
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#define TIM2_CR1 (*(volatile uint32_t *)(TIM2_BASE + 0x00))
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#define TIM2_DIER (*(volatile uint32_t *)(TIM2_BASE + 0x0c))
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#define TIM2_CNT (*(volatile uint32_t *)(TIM2_BASE + 0x24))
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#define TIM2_PSC (*(volatile uint32_t *)(TIM2_BASE + 0x28))
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#define TIM2_ARR (*(volatile uint32_t *)(TIM2_BASE + 0x2c))
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#define TIM_DIER_UIE (1 << 0)
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#define TIM_CR1_CLOCK_ENABLE (1 << 0)
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#define TIM_CR1_UPD_RS (1 << 2)
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#define TIM_CR1_EV_DISABLE (1 << 1)
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int timer_init(uint32_t clock, uint32_t prescaler, uint32_t interval_ms)
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{
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uint32_t val = 0;
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uint32_t psc = 1;
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uint32_t err = 0;
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uint32_t reg = 0;
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clock = ((clock * prescaler) / 2000) * interval_ms;
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while (psc < 65535) {
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val = clock / psc;
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err = clock % psc;
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if ((val < 65535) && (err == 0)) {
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val--;
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break;
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}
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val = 0;
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psc++;
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}
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if (val == 0)
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return -1;
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nvic_irq_enable(NVIC_TIM2_IRQN);
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nvic_irq_setprio(NVIC_TIM2_IRQN, 4);
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APB1_CLOCK_RST |= TIM2_APB1_CLOCK_ER_VAL;
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DMB();
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APB1_CLOCK_RST &= ~TIM2_APB1_CLOCK_ER_VAL;
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APB1_CLOCK_ER |= TIM2_APB1_CLOCK_ER_VAL;
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TIM2_CR1 = 0;
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DMB();
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TIM2_PSC = psc;
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TIM2_ARR = val;
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TIM2_CNT = val - 1;
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reg = TIM2_CR1;
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reg &= ~TIM_CR1_EV_DISABLE;
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reg |= TIM_CR1_CLOCK_ENABLE;
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TIM2_CR1 = reg;
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TIM2_DIER |= TIM_DIER_UIE;
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DMB();
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return 0;
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}
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void timer_disable(void)
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{
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APB1_CLOCK_RST |= TIM2_APB1_CLOCK_ER_VAL;
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DMB();
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APB1_CLOCK_RST &= ~TIM2_APB1_CLOCK_ER_VAL;
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TIM2_CR1 |= TIM_CR1_EV_DISABLE;
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APB1_CLOCK_ER &= ~TIM2_APB1_CLOCK_ER_VAL;
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}
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