initial commit

src/main.c

@@ -0,0 +1,85 @@
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/rcc.h>
+
+#define LED_OR_PORT GPIOC
+#define LED_OR_PIN GPIO10
+
+#define LED_GR_PORT GPIOC
+#define LED_GR_PIN GPIO11
+
+#define LED_RD_PORT GPIOC
+#define LED_RD_PIN GPIO12
+
+#define COUNT_PERIOD_MS 500
+
+static volatile uint32_t s_ticks = 0;
+
+void sys_tick_handler(void) { s_ticks++; }
+
+static void delay_ms(uint32_t ms) {
+  uint32_t until = s_ticks + ms;
+  while (s_ticks < until)
+    ;
+}
+
+static void clock_setup(void) {
+  rcc_clock_setup_pll(&rcc_hsi_configs[RCC_CLOCK_3V3_170MHZ]);
+}
+
+static void systick_setup(void) {
+  /* 1 ms tick at 170 MHz core clock */
+  systick_set_reload(rcc_ahb_frequency / 1000 - 1);
+  systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
+  systick_counter_enable();
+  systick_interrupt_enable();
+}
+
+static void gpio_setup(void) {
+  rcc_periph_clock_enable(RCC_GPIOC);
+
+  gpio_mode_setup(LED_OR_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_OR_PIN);
+  gpio_mode_setup(LED_GR_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_GR_PIN);
+  gpio_mode_setup(LED_RD_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_RD_PIN);
+
+  gpio_set_output_options(LED_OR_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_LOW,
+                          LED_OR_PIN);
+  gpio_set_output_options(LED_GR_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_LOW,
+                          LED_GR_PIN);
+  gpio_set_output_options(LED_RD_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_LOW,
+                          LED_RD_PIN);
+
+  gpio_clear(LED_OR_PORT, LED_OR_PIN);
+  gpio_clear(LED_GR_PORT, LED_GR_PIN);
+  gpio_set(LED_RD_PORT, LED_RD_PIN); // active low
+}
+
+static void gpio_write(uint32_t gpioport, uint16_t gpios, uint8_t value) {
+  if (value == 0) {
+    gpio_clear(gpioport, gpios);
+  } else {
+    gpio_set(gpioport, gpios);
+  }
+}
+
+static void set_binary_counter(uint8_t value) {
+  gpio_write(LED_OR_PORT, LED_OR_PIN, value & 0x04);
+  gpio_write(LED_GR_PORT, LED_GR_PIN, value & 0x02);
+  gpio_write(LED_RD_PORT, LED_RD_PIN, value & 0x01);
+}
+
+int main(void) {
+  clock_setup();
+  systick_setup();
+  gpio_setup();
+
+  uint8_t counter = 0;
+
+  while (1) {
+    set_binary_counter(counter);
+    delay_ms(COUNT_PERIOD_MS);
+    counter++; // overflow is fine
+  }
+
+  return 0;
+}