PWM timer on PA0

main.c

@@ -1,4 +1,5 @@
 #include "system.h"
+#include "timer.h"
 #include "uart.h"
 #include <libopencm3/cm3/nvic.h>
 #include <libopencm3/cm3/systick.h>
@@ -15,7 +16,14 @@ static void gpio_setup(void) {
 
     /* Setup GPIO6 and 7 (in GPIO port A) for LED use. */
     gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO12);
+
+    /*
+     * Set TIM1 channel output pins to
+     * 'output alternate function push-pull'.
+     */
+    gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_TIM2_CH1_ETR);
 }
+
 static void clock_setup(void) {
     rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
 
@@ -35,12 +43,15 @@ int main(void) {
     gpio_setup();
     sys_tick_setup();
     usart_setup();
+    timer_setup();
 
     printf("Printf is working!\n");
 
     gpio_clear(GPIOC, GPIO13);
     gpio_set(GPIOC, GPIO13);
 
+    timer_pwm_set_duty(75.0);
+
     uint64_t init = sys_ticks_get();
     while (sys_ticks_get() == init);
 

timer.c

@@ -0,0 +1,19 @@
+#include "timer.h"
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/timer.h>
+
+void timer_setup(void) {
+    rcc_periph_clock_enable(RCC_TIM2);
+    timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
+    timer_set_oc_mode(TIM2, TIM_OC1, TIM_OCM_PWM1);
+    timer_enable_counter(TIM2);
+    timer_enable_oc_output(TIM2, TIM_OC1);
+
+    timer_set_prescaler(TIM2, PRESCALER - 1);
+    timer_set_period(TIM2, ARR_VAL - 1);
+}
+
+void timer_pwm_set_duty(float duty) {
+    const float raw = (float)ARR_VAL * (duty / 100.0f);
+    timer_set_oc_value(TIM2, TIM_OC1, (uint32_t)raw);
+}

timer.h

@@ -0,0 +1,9 @@
+#pragma once
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/timer.h>
+
+#define PRESCALER (72)
+#define ARR_VAL   (1000)
+
+void timer_setup(void);
+void timer_pwm_set_duty(float duty);