/* * This file is part of the libopencm3 project. * * Copyright (C) 2010 Thomas Otto * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #include #include #include #include #include void gpio_setup(void) { /* Enable GPIOB clock. */ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN); /* Set GPIO6/7 (in GPIO port B) to 'output push-pull' for the LEDs. */ gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO6); gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO7); } void nvic_setup() { /* without this the timer interrupt routine will never be called */ nvic_enable_irq(NVIC_TIM2_IRQ); nvic_set_priority(NVIC_TIM2_IRQ, 1); } void tim2_isr() { /* LED2 on/off */ gpio_toggle(GPIOB, GPIO6); /* clear interrrupt flag */ TIM_SR(TIM2) &= ~TIM_SR_UIF; } int main(void) { rcc_clock_setup_in_hse_16mhz_out_72mhz(); gpio_setup(); nvic_setup(); gpio_clear(GPIOB, GPIO7); /* LED1 on */ gpio_set(GPIOB, GPIO6); /* LED2 off */ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM2EN); /* the goal is to let the LED2 glow for a second and then be off for a second */ /* Set timer start value */ TIM_CNT(TIM2) = 1; /* Set timer prescaler. 72MHz/1440 => 50000 counts per second */ TIM_PSC(TIM2) = 1440; /* End timer value. If this value is reached an interrupt is generated */ TIM_ARR(TIM2) = 50000; /* Update interrupt enable */ TIM_DIER(TIM2) |= TIM_DIER_UIE; /* Start timer */ TIM_CR1(TIM2) |= TIM_CR1_CEN; while(1); /* Halt. */ return 0; }