diff --git a/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.c b/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.c
index dd961db..550c417 100644
--- a/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.c
+++ b/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.c
@@ -1,10 +1,106 @@
 /**
  * @file watch_power_management.h
  * @author Anatole SCHRAMM-HENRY
- * @brief Watch power management functions API header file
+ * @brief Watch power management functions API source file
  * @version 0.1
  * @date 2023-10-12
  * 
  * @copyright MIT
  * 
- */
\ No newline at end of file
+ */
+
+#include "watch_power_management.h"
+#include "app_common.h"
+#include "lv_port_tick.h"
+
+static struct
+{
+    watch_power_state_e current_power_state;
+    enum CPU_CLK cpu_clock_idle;
+    enum CPU_CLK cpu_clock_full_speed;
+} _watch_power_management = {
+    .current_power_state = WATCH_POWER_STATE_FULL_SPEED,
+    .cpu_clock_idle = CPU_CLK_80M,
+    .cpu_clock_full_speed = CPU_CLK_160M,
+    };
+
+/**
+ * @brief Helper function to change the CPU clock of the micro.
+ * Internally checks that the new clock is different to the current one.
+ * 
+ * @param cpu_clock the new frequency to apply @ref enum CPU_CLK
+ */
+static void _set_cpu_clock(enum CPU_CLK cpu_clock);
+
+static enum CPU_CLK _cpu_frequency_to_CPU_CLK(uint32_t frequency);
+
+static uint32_t _CPU_CLK_to_cpu_frequency(enum CPU_CLK cpu_clock);
+
+void watch_power_management_change_power_state(watch_power_state_e power_state)
+{
+    // If we are already in this power state, then there is nothing more to do.
+    if(power_state == _watch_power_management.current_power_state) return;
+
+    switch (power_state)
+    {
+    case WATCH_POWER_STATE_IDLE:
+        // We set the CPU clock to the value defined for the IDLE state
+        _set_cpu_clock(_watch_power_management.cpu_clock_idle);
+        break;
+    case WATCH_POWER_STATE_FULL_SPEED:
+        // We set the CPU clock to the value defined for the FULL SPEED state
+        _set_cpu_clock(_watch_power_management.cpu_clock_full_speed);
+        break;
+    case WATCH_POWER_STATE_SLEEP:
+        break;
+    case WATCH_POWER_STATE_BLE_SLEEP:
+        APP_LOG_INFO("Entering BLE sleep mode");
+        // We set the CPU clock to 40MHz (can't go lower or the BLE radio will stop working)
+        _set_cpu_clock(CPU_CLK_40M);
+        // We can stop the lvgl timer
+        APP_LOG_INFO("Stopping LVGL tick timer");
+        lv_port_tick_stop();
+        break;
+    case WACTH_POWER_STATE_STANDBY:
+    default:
+        break;
+    }
+
+    // Let's apply the new power state
+    _watch_power_management.current_power_state = power_state;
+}
+
+watch_power_state_e watch_power_management_get_current_power_state(void)
+{
+    return _watch_power_management.current_power_state;
+}
+
+bool watch_power_management_check_current_power_state_is(watch_power_state_e power_state)
+{
+    return power_state == _watch_power_management.current_power_state;
+}
+
+static void _set_cpu_clock(enum CPU_CLK cpu_clock)
+{
+    // First let's get the current clock speed
+    tls_sys_clk clk;
+    tls_sys_clk_get(&clk);
+
+    // If the current clock is different from the clock we want to apply :
+    if(_cpu_frequency_to_CPU_CLK(clk.cpuclk) != cpu_clock)
+    {
+        tls_sys_clk_set(cpu_clock);
+        APP_LOG_INFO("New CPU frequency : %u MHz", _CPU_CLK_to_cpu_frequency(cpu_clock));
+    }
+}
+
+static enum CPU_CLK _cpu_frequency_to_CPU_CLK(uint32_t frequency)
+{
+    return W800_PLL_CLK_MHZ / frequency;
+}
+
+static uint32_t _CPU_CLK_to_cpu_frequency(enum CPU_CLK cpu_clock)
+{
+    return W800_PLL_CLK_MHZ / cpu_clock;
+}
+ 
\ No newline at end of file
diff --git a/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.h b/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.h
index 16653e9..fb51690 100644
--- a/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.h
+++ b/src/W800_SDK_v1.00.10/app/app_drivers/watch_power_management/watch_power_management.h
@@ -12,6 +12,9 @@
 #ifndef WATCH_POWER_MANAGEMENT_H
 #define WATCH_POWER_MANAGEMENT_H
 
+#include "wm_type_def.h"
+#include "wm_cpu.h"
+
 typedef enum watch_power_state
 {
     /**
@@ -47,9 +50,10 @@ typedef enum watch_power_state
     WACTH_POWER_STATE_STANDBY,
 } watch_power_state_e;
 
-typedef struct watch_power_management
-{
-    watch_power_state_e current_power_state;
-} watch_power_management_t;
+void watch_power_management_change_power_state(watch_power_state_e power_state);
+
+watch_power_state_e watch_power_management_get_current_power_state(void);
+
+bool watch_power_management_check_current_power_state_is(watch_power_state_e power_state);
 
 #endif //WATCH_POWER_MANAGEMENT_H
\ No newline at end of file