/* * This file is part of the Trezor project, https://trezor.io/ * * Copyright (C) 2016 Saleem Rashid <trezor@saleemrashid.com> * * This library is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This library 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library. If not, see <http://www.gnu.org/licenses/>. */ #include "timer.h" #include <libopencm3/cm3/systick.h> #include <libopencm3/cm3/vector.h> #include <libopencm3/stm32/rcc.h> /* 1 tick = 1 ms */ extern volatile uint32_t system_millis; /* * Initialise the Cortex-M3 SysTick timer */ void timer_init(void) { system_millis = 0; /* * MCU clock (120 MHz) as source * * (120 MHz / 8) = 15 clock pulses * */ systick_set_clocksource(STK_CSR_CLKSOURCE_AHB_DIV8); STK_CVR = 0; /* * 1 tick = 1 ms @ 120 MHz * * (15 clock pulses * 1000 ms) = 15000 clock pulses * * Send an interrupt every (N - 1) clock pulses */ systick_set_reload(14999); /* SysTick as interrupt */ systick_interrupt_enable(); systick_counter_enable(); } void sys_tick_handler(void) { system_millis++; }