Systick

main.c

@@ -1,17 +1,39 @@
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/flash.h>
 #include <libopencm3/stm32/gpio.h>
 #include <libopencm3/stm32/rcc.h>
+#include <stdint.h>
 
-static void clock_setup(void) {
-    // Use external 8 MHz HSE and PLL to 72 MHz
-    rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
-    rcc_periph_clock_enable(RCC_GPIOC);
-}
+volatile uint64_t ticks;
 
 static void gpio_setup(void) {
-    // gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO13);
+    rcc_periph_clock_enable(RCC_GPIOC);
     gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
 }
 
+void sys_tick_handler(void) { ticks++; }
+
+static void sys_tick_setup(void) {
+    ticks = 0;
+    // rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE16_72MHZ]);
+
+    // systick_set_clocksource(STK_CSR_CLKSOURCE_AHB_DIV8);
+    systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
+
+    // systick_set_reload(48000 - 1);
+    systick_set_frequency(1000, 72000000);
+
+    systick_clear();
+
+    systick_interrupt_enable();
+    systick_counter_enable();
+
+    return;
+}
+
+static uint64_t sys_ticks_get(void) { return ticks; }
+
 static void delay(volatile uint32_t count) {
     while (count-- > 0) {
         __asm__("nop");
@@ -19,13 +41,31 @@ static void delay(volatile uint32_t count) {
 }
 
 int main(void) {
-    clock_setup();
+    rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
+    // rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSI_48MHZ]);
     gpio_setup();
+    sys_tick_setup();
 
+    gpio_clear(GPIOC, GPIO13);
+    gpio_set(GPIOC, GPIO13);
+    // gpio_set(GPIOB, GPIO6);    /* LED2 off */
+
+    // ticks = 0;
+
+    uint64_t init = sys_ticks_get();
+    while (sys_ticks_get() == init);
+
+    /* We call this handler every 1ms so 1000ms = 1s on/off. */
+    uint64_t ref = 0;
     while (1) {
-        gpio_toggle(GPIOC, GPIO13); // On Blue Pill: LED is on PC13
-        delay(10000000);            // Crude delay loop
+        if (sys_ticks_get() > ref) {
+            ref += 500;
+            gpio_toggle(GPIOC, GPIO13);
+            // while (sys_ticks_get() % 1000 == 0);
+        }
     }
 
+    while (1);
+
     return 0;
 }