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60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/*
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* This file is part of the Trezor project, https://trezor.io/
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*
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* Copyright (C) 2016 Saleem Rashid <trezor@saleemrashid.com>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser 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 library 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "timer.h"
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#include <libopencm3/cm3/systick.h>
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#include <libopencm3/cm3/vector.h>
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#include <libopencm3/stm32/rcc.h>
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/* 1 tick = 1 ms */
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extern volatile uint32_t system_millis;
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/*
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* Initialise the Cortex-M3 SysTick timer
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*/
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void timer_init(void) {
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system_millis = 0;
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/*
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* MCU clock (120 MHz) as source
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*
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* (120 MHz / 8) = 15 clock pulses
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*
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*/
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systick_set_clocksource(STK_CSR_CLKSOURCE_AHB_DIV8);
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STK_CVR = 0;
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/*
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* 1 tick = 1 ms @ 120 MHz
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*
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* (15 clock pulses * 1000 ms) = 15000 clock pulses
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*
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* Send an interrupt every (N - 1) clock pulses
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*/
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systick_set_reload(14999);
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/* SysTick as interrupt */
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systick_interrupt_enable();
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systick_counter_enable();
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}
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void sys_tick_handler(void) { system_millis++; }
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