restructuring

deprecated/F0/blink/systick_blink.c

@@ -0,0 +1,82 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.com>
+ * Copyright (C) 2013 Onno Kortmann <onno@gmx.net>
+ * Copyright (C) 2013 Frantisek Burian <BuFran@seznam.cz> (merge)
+ *
+ * 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 <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/systick.h>
+
+#include "stm32f0.h"
+
+/* Called when systick fires */
+void sys_tick_handler(void){
+    pin_toggle(GPIOB, GPIO3);
+}
+
+/*
+ * Set up timer to fire every x milliseconds
+ * This is a unusual usage of systick, be very careful with the 24bit range
+ * of the systick counter!  You can range from 1 to 2796ms with this.
+ */
+static void systick_setup(int xms){
+    static int curms = 0;
+    if(curms == xms) return;
+    // 6MHz
+    systick_set_clocksource(STK_CSR_CLKSOURCE_EXT);
+    /* clear counter so it starts right away */
+    STK_CVR = 0;
+
+    systick_set_reload(6000 * xms);
+    systick_counter_enable();
+    systick_interrupt_enable();
+    curms = xms;
+}
+
+/* set STM32 to clock by 48MHz from HSI oscillator */
+static void clock_setup(void){
+    rcc_clock_setup_in_hsi_out_48mhz();
+    //rcc_clock_setup_in_hse_8mhz_out_48mhz();
+
+    /* Enable clocks to the GPIO subsystems (A&B) */
+    RCC_AHBENR = RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
+}
+
+static void gpio_setup(void){
+    /* Set green led (PB3) as output */
+    gpio_mode_setup(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO3);
+    /* D2 - PA12 - switch blink rate (pullup input) */
+    gpio_mode_setup(GPIOA, GPIO_MODE_INPUT, GPIO_PUPD_PULLUP, GPIO12);
+}
+
+
+int main(void){
+    clock_setup();
+    gpio_setup();
+
+    /* 500ms ticks =>  1000ms period => 1Hz blinks */
+    systick_setup(500);
+
+    /* Do nothing in main loop */
+    while (1){
+        if(pin_read(GPIOA, GPIO12)) systick_setup(125); // no jumper - 4Hz
+        else systick_setup(500); // 1Hz
+    }
+}