diff --git a/Core/Inc/led.h b/Core/Inc/led.h
new file mode 100644
index 0000000..31262e4
--- /dev/null
+++ b/Core/Inc/led.h
@@ -0,0 +1,17 @@
+#ifndef __LED_H
+#define __LED_H
+
+#include "main.h"
+
+#define LED_R 1
+#define LED_G 2
+#define LED_B 4
+#define LED_ALL 7
+
+void LED_Start(uint8_t led);
+void LED_Stop(uint8_t led);
+
+// duty in [0, 100]
+void LED_SetDuty(uint8_t r, uint8_t g, uint8_t b);
+
+#endif
diff --git a/Core/Src/led.c b/Core/Src/led.c
new file mode 100644
index 0000000..cdf511d
--- /dev/null
+++ b/Core/Src/led.c
@@ -0,0 +1,34 @@
+#include "led.h"
+#include "tim.h"
+
+#define LED_TIM (&htim3)
+#define LED_R_CHAN TIM_CHANNEL_4
+#define LED_G_CHAN TIM_CHANNEL_3
+#define LED_B_CHAN TIM_CHANNEL_2
+
+void LED_Start(uint8_t led)
+{
+  if (led & LED_R)
+    HAL_TIM_PWM_Start(LED_TIM, LED_R_CHAN);
+  if (led & LED_G)
+    HAL_TIM_PWM_Start(LED_TIM, LED_G_CHAN);
+  if (led & LED_B)
+    HAL_TIM_PWM_Start(LED_TIM, LED_B_CHAN);
+}
+
+void LED_Stop(uint8_t led)
+{
+  if (led & LED_R)
+    HAL_TIM_PWM_Stop(LED_TIM, LED_R_CHAN);
+  if (led & LED_G)
+    HAL_TIM_PWM_Stop(LED_TIM, LED_G_CHAN);
+  if (led & LED_B)
+    HAL_TIM_PWM_Stop(LED_TIM, LED_B_CHAN);
+}
+
+void LED_SetDuty(uint8_t r, uint8_t g, uint8_t b)
+{
+  __HAL_TIM_SetCompare(LED_TIM, LED_R_CHAN, r);
+  __HAL_TIM_SetCompare(LED_TIM, LED_G_CHAN, g);
+  __HAL_TIM_SetCompare(LED_TIM, LED_B_CHAN, b);
+}