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-rw-r--r--examples/other/timer_interrupt/timer.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/examples/other/timer_interrupt/timer.c b/examples/other/timer_interrupt/timer.c
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+++ b/examples/other/timer_interrupt/timer.c
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+/*
+ * This file is part of the libopenstm32 project.
+ *
+ * Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <libopenstm32/rcc.h>
+#include <libopenstm32/flash.h>
+#include <libopenstm32/gpio.h>
+#include <libopenstm32/usart.h>
+#include <libopenstm32/timer.h>
+#include <libopenstm32/nvic.h>
+
+/* Set STM32 to 72 MHz. HSE 16MHz */
+void clock_setup(void)
+{
+ /* enable Internal High Speed Oscillator */
+ rcc_osc_on(HSI);
+ rcc_wait_for_osc_ready(HSI);
+
+ /* Select HSI as SYSCLK source. */
+ rcc_set_sysclk_source(SW_SYSCLKSEL_HSICLK);
+
+ /* enable External High Speed Oscillator 16MHz */
+ rcc_osc_on(HSE);
+ rcc_wait_for_osc_ready(HSE);
+ rcc_set_sysclk_source(SW_SYSCLKSEL_HSECLK);
+
+ /* set prescalers for ADC, ABP1, ABP2... make this before touching the PLL */
+ rcc_set_hpre(HPRE_SYSCLK_NODIV); //prescales the AHB clock from the SYSCLK
+ rcc_set_adcpre(ADCPRE_PLCK2_DIV6); //prescales the ADC from the APB2 clock; max 14MHz
+ rcc_set_ppre1(PPRE1_HCLK_DIV2); //prescales the APB1 from the AHB clock; max 36MHz
+ rcc_set_ppre2(PPRE2_HCLK_NODIV); //prescales the APB2 from the AHB clock; max 72MHz
+
+ /* sysclk should run with 72MHz -> 2 Waitstates ; choose 0WS from 0-24MHz, 1WS from 24-48MHz, 2WS from 48-72MHz */
+ flash_set_ws(FLASH_LATENCY_2WS);
+
+ /* Set the PLL multiplication factor to 9. -> 16MHz (external) * 9 (multiplier) / 2 (PLLXTPRE_HSE_CLK_DIV2) = 72MHz */
+ rcc_set_pll_multiplication_factor(PLLMUL_PLL_CLK_MUL9);
+
+ /* Select HSI as PLL source. */
+ rcc_set_pll_source(PLLSRC_HSE_CLK);
+
+ /* divide external frequency by 2 before entering pll (only valid/needed for HSE) */
+ rcc_set_pllxtpre(PLLXTPRE_HSE_CLK_DIV2);
+
+ /* Enable PLL oscillator and wait for it to stabilize. */
+ rcc_osc_on(PLL);
+ rcc_wait_for_osc_ready(PLL);
+
+ /* Select PLL as SYSCLK source. */
+ rcc_set_sysclk_source(SW_SYSCLKSEL_PLLCLK);
+}
+
+void gpio_setup(void)
+{
+ /* Enable GPIOB clock. */
+ rcc_peripheral_enable_clock(&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 intterrupt routing will newer 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)
+{
+ clock_setup();
+ gpio_setup();
+ nvic_setup();
+
+ gpio_clear(GPIOB, GPIO7); /* LED1 on */
+ gpio_set(GPIOB, GPIO6); /* LED2 off */
+
+ rcc_peripheral_enable_clock(&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;
+}