diff --git a/Kernel.cpp b/Kernel.cpp
index 01e725f..2152ed5 100644
--- a/Kernel.cpp
+++ b/Kernel.cpp
@@ -10,6 +10,7 @@ struct Task *Kernel_get_task(int pid);
 struct Task tasks[MAX_TASKS];
 int next_pid = 1;
 unsigned long last_tick;
+bool inputs[2] = {false, false};
 
 void Kernel_panic(char* message)
 {
@@ -25,9 +26,10 @@ void Kernel_panic(char* message)
 void Kernel_setup()
 {
   last_tick = millis();
+  //Serial.begin(115200);
 }
 
-void Kernel_start(int (*callback)(unsigned int), unsigned long interval)
+void Kernel_start(int (*callback)(int, unsigned int), unsigned long interval)
 {
   struct Task *process = Kernel_get_task(0);
   if (process->pid == -1)
@@ -77,6 +79,64 @@ void Kernel_reap(int pid)
   process->signal_mask = 0xFFFF;
 }
 
+void Kernel_signal(unsigned int signal)
+{
+  for (int i=0; i<MAX_TASKS; i++)
+  {
+    if (tasks[i].pid != 0 && tasks[i].running == true)
+    {
+      tasks[i].signal |= signal;
+    }
+  }
+}
+
+void Kernel_signal(int pid, unsigned int signal)
+{
+  struct Task *process = Kernel_get_task(pid);
+  if (process->pid == pid)
+  {
+    process->signal |= signal;
+  }
+}
+
+void Kernel_signal_mask(int pid, unsigned int signal_mask)
+{
+  struct Task *process = Kernel_get_task(pid);
+  if (process->pid == pid)
+  {
+    process->signal_mask = signal_mask;
+  }
+}
+
+unsigned long Kernel_get_run_interval(int pid)
+{
+  struct Task *process = Kernel_get_task(pid);
+  return process->pid == pid ? process->run_interval : 0;
+}
+
+void Kernel_set_run_interval(int pid, unsigned long interval)
+{
+  struct Task *process = Kernel_get_task(pid);
+  if (process->pid == pid)
+  {
+    process->run_interval = interval;
+  }
+  
+}
+
+int Kernel_count_running_tasks()
+{
+  int count = 0;
+  for (int i=0; i<MAX_TASKS; i++)
+  {
+    if (tasks[i].pid != 0 && tasks[i].running)
+    {
+      count++;
+    }
+  }
+  return count;
+}
+
 int Kernel_get_exit_code(int pid)
 {
   struct Task *process = Kernel_get_task(pid);
@@ -91,6 +151,13 @@ bool Kernel_is_exited(int pid)
   return process->pid != pid || process->running == false;
 }
 
+bool Kernel_read_input(int input)
+{
+  bool value = inputs[input];
+  inputs[input] = false;
+  return value;
+}
+
 struct Task *Kernel_get_task(int pid)
 {
   for (int i=0; i<MAX_TASKS; i++)
@@ -124,25 +191,33 @@ void Kernel_tick()
       // Make sure we found at least one active process, because if not we dead.
       running_tasks++;
 
-      // Check if this tick's duration will push us over the run interval and if so set the TICK signal
-      if (tasks[i].run_accumulator + duration > tasks[i].run_interval)
+      // Check if this process is running on a schedule and this tick's duration will push us over the run interval and if so set the TICK signal
+      // run_interval 0 is a special case of "run whenever we run", so set TICK any time we get here
+      if (tasks[i].run_interval > 0)
       {
-        // Set signal
-        tasks[i].signal |= SIGNAL_TICK;
-        // Reset accumulator so we can start counting again
-        tasks[i].run_accumulator = 0;
+        if (tasks[i].run_accumulator + duration > tasks[i].run_interval)
+        {
+          // Set signal
+          tasks[i].signal |= SIGNAL_TICK;
+          // Reset accumulator so we can start counting again
+          tasks[i].run_accumulator = 0;
+        }
+        else
+        {
+          // Otherwise, accumulate time
+          tasks[i].run_accumulator += duration;
+        }
       }
       else
       {
-        // Otherwise, accumulate time
-        tasks[i].run_accumulator += duration;
+        tasks[i].signal |= SIGNAL_TICK;
       }
 
       // If the process has any non-masked signals pending, run it
       if ((tasks[i].signal & tasks[i].signal_mask) != 0)
       {
         // Run the task
-        int task_return = (*tasks[i].callback)(tasks[i].signal);
+        int task_return = (*tasks[i].callback)(tasks[i].pid, tasks[i].signal);
         // Reset the signal
         tasks[i].signal = SIGNAL_NONE;
 
@@ -162,7 +237,7 @@ void Kernel_tick()
 
       // Check each task to see if it's the one scheduled to run on the next closest tick, and track it
       // so we can put the processor to sleep until then.
-      if (tasks[i].running && tasks[i].run_interval - tasks[i].run_accumulator < next_tick_due)
+      if (tasks[i].running && tasks[i].run_interval > 0 && tasks[i].run_interval - tasks[i].run_accumulator < next_tick_due)
       {
         next_tick_due = tasks[i].run_interval - tasks[i].run_accumulator;
       }
@@ -176,9 +251,35 @@ void Kernel_tick()
     Kernel_panic(panic_msg);
   }
 
-  // Put processor to sleep until the next scheduled run of a task
+  // If no signals pending, put processor to sleep until the next scheduled run of a task
   // Leave the home button enabled to force a wake-up before then
-  esp_sleep_enable_timer_wakeup(next_tick_due * 1000);
-  esp_sleep_enable_ext0_wakeup((gpio_num_t)37, LOW);
-  esp_light_sleep_start();
+  bool signals_pending = false;
+  for (int i=0; i<MAX_TASKS; i++)
+  {
+    if (tasks[i].signal != SIGNAL_NONE)
+    {
+      signals_pending = true;
+    }
+  }
+  if (!signals_pending)
+  {
+    esp_sleep_enable_timer_wakeup(next_tick_due * 1000);
+    esp_sleep_enable_ext0_wakeup((gpio_num_t)37, LOW);
+    esp_sleep_enable_ext1_wakeup(0x8000000000, ESP_EXT1_WAKEUP_ALL_LOW);
+    esp_light_sleep_start();
+
+    esp_sleep_wakeup_cause_t wakeup_reason;
+    wakeup_reason = esp_sleep_get_wakeup_cause();
+    switch(wakeup_reason){
+      case ESP_SLEEP_WAKEUP_TIMER     : break;
+      case ESP_SLEEP_WAKEUP_EXT0      : inputs[0] = true; break;
+      case ESP_SLEEP_WAKEUP_EXT1      : inputs[1] = true; break;
+      case ESP_SLEEP_WAKEUP_TOUCHPAD  : break;
+      case ESP_SLEEP_WAKEUP_ULP       : break;
+      case ESP_SLEEP_WAKEUP_GPIO      : break;
+      case ESP_SLEEP_WAKEUP_UART      : break;
+      default                         : break;
+    }
+  }
+  
 }
diff --git a/Kernel.h b/Kernel.h
index 78cf6f7..088b982 100644
--- a/Kernel.h
+++ b/Kernel.h
@@ -4,7 +4,7 @@ struct Task
   int pid = 0;
   bool running = false;
   int exit_code = 0;
-  int (*callback)(unsigned int);
+  int (*callback)(int, unsigned int);
   unsigned long run_interval = 0;
   unsigned long run_accumulator = 0;
   unsigned int signal = 0;
@@ -18,7 +18,7 @@ void Kernel_tick();
 void Kernel_panic(char* message);
 
 // Start a new process
-void Kernel_start(int (*callback)(unsigned int), unsigned long interval);
+void Kernel_start(int (*callback)(int, unsigned int), unsigned long interval);
 // Continue execution of a process
 void Kernel_enable(int pid);
 // Pause execution of a process
@@ -26,12 +26,33 @@ void Kernel_disable(int pid);
 // Clean up exited process
 void Kernel_reap(int pid);
 
+// Send a signal to a/all processes
+void Kernel_signal(int pid, unsigned int signal);
+void Kernel_signal(unsigned int signal);
+
+// Set a tasks's signal mask
+void Kernel_signal_mask(int pid, unsigned int signal_mask);
+
+// Get the run interval of a process
+unsigned long Kernel_get_run_interval(int pid);
+
+// Count how many tasks are running
+int Kernel_count_running_tasks();
+
 // Check if process has exited
 bool Kernel_is_exited(int pid);
 // Get exit code of process
 int Kernel_get_exit_code(int pid);
 
-#define SIGNAL_NONE 0
-#define SIGNAL_TICK 1
-#define SIGNAL_START 2
-#define SIGNAL_STOP 4
+// Check if a button was pressed
+bool Kernel_read_input(int input);
+
+#define SIGNAL_NONE     0x0000
+#define SIGNAL_TICK     0x0001
+#define SIGNAL_START    0x0002
+#define SIGNAL_STOP     0x0004
+#define SIGNAL_INPUT_A  0x0008
+#define SIGNAL_INPUT_B  0x0010
+
+#define KERNEL_INPUT_BUTTON_A 0
+#define KERNEL_INPUT_BUTTON_B 1
diff --git a/PowerManagement.cpp b/PowerManagement.cpp
index 1b0ef84..e6540d8 100644
--- a/PowerManagement.cpp
+++ b/PowerManagement.cpp
@@ -1,10 +1,78 @@
+#include <M5StickC.h>
+#include "Kernel.h"
+#include "PowerManagement.h"
 
-void PowerManagement_setup()
+#define IDLE_TIMEOUT 5000
+#define SLEEP_TIMEOUT 10000
+
+#define POWER_STATE_WAKE 0
+#define POWER_STATE_IDLE 1
+#define POWER_STATE_SLEEP 2
+
+unsigned long accumulator = 0;
+int power_state = 0;
+
+void sleep()
 {
-  
+  power_state = POWER_STATE_SLEEP;
+  M5.Axp.DeepSleep();
 }
 
-void PowerManagement_tick()
+void idle()
 {
+  power_state = POWER_STATE_IDLE;
+  M5.Axp.ScreenBreath(7); 
+}
+
+void wake()
+{
+  power_state = POWER_STATE_WAKE;
+  M5.Axp.ScreenBreath(12);
+}
 
+int PowerManagement(int pid, unsigned int signal)
+{
+  // Receive start/stop/input/tick signals
+  if (signal & SIGNAL_START)
+  {
+    Kernel_signal_mask(pid, SIGNAL_START | SIGNAL_STOP | SIGNAL_INPUT_A | SIGNAL_INPUT_B | SIGNAL_TICK);
+  }
+
+  // Accumulate time every time we run
+  if ((signal & SIGNAL_START) == 0 && signal & SIGNAL_TICK)
+  {
+    accumulator += Kernel_get_run_interval(pid);
+  }
+
+  // But reset it whenever a button is pressed
+  if ((signal & SIGNAL_INPUT_A) != 0 || (signal & SIGNAL_INPUT_B) != 0)
+  {
+    if (power_state != POWER_STATE_WAKE)
+    {
+      wake();
+    }
+    accumulator = 0;
+  }
+
+  switch (power_state)
+  {
+    case POWER_STATE_WAKE:
+      if (accumulator > IDLE_TIMEOUT)
+      {
+        idle();
+      }
+      break;
+    case POWER_STATE_IDLE:
+      if (accumulator > SLEEP_TIMEOUT)
+      {
+        sleep();
+      }
+      break;
+  }
+
+  // TODO: On sleep, signal "STOP" to all tasks and reschedule ourselves more frequently
+  // Wait until Kernel_count_running == 1, then put chip to sleep
+
+  return 0;
+  
 }
diff --git a/PowerManagement.h b/PowerManagement.h
index da44c18..9cc4c4e 100644
--- a/PowerManagement.h
+++ b/PowerManagement.h
@@ -1,3 +1,2 @@
 
-void PowerManagement_setup();
-void PowerManagement_tick();
+int PowerManagement(int pid, unsigned int signal);
diff --git a/UserInput.cpp b/UserInput.cpp
new file mode 100644
index 0000000..b8be5aa
--- /dev/null
+++ b/UserInput.cpp
@@ -0,0 +1,25 @@
+#include <M5StickC.h>
+#include "Kernel.h"
+
+int UserInput(int pid, unsigned int signal)
+{
+  Serial.println("UserInput called");
+  if (signal & SIGNAL_START)
+  {
+    Kernel_signal_mask(pid, SIGNAL_START | SIGNAL_STOP | SIGNAL_TICK);
+  }
+  if (signal & SIGNAL_TICK)
+  {
+    if (Kernel_read_input(KERNEL_INPUT_BUTTON_A))
+    {
+      Kernel_signal(SIGNAL_INPUT_A);
+    }
+    
+    if (Kernel_read_input(KERNEL_INPUT_BUTTON_B))
+    {
+      Kernel_signal(SIGNAL_INPUT_B);
+    }
+  }
+
+  return 0;
+}
diff --git a/UserInput.h b/UserInput.h
new file mode 100644
index 0000000..78c5588
--- /dev/null
+++ b/UserInput.h
@@ -0,0 +1,2 @@
+
+int UserInput(int pid, unsigned int signal);
diff --git a/watchos.ino b/watchos.ino
index 22a4d10..e8a4a2f 100644
--- a/watchos.ino
+++ b/watchos.ino
@@ -1,10 +1,12 @@
 #include <M5StickC.h>
-#include "PowerManagement.h"
 #include "Kernel.h"
 #include "Colours.h"
 
+#include "PowerManagement.h"
+#include "UserInput.h"
+
 int count = 0;
-int test_func(unsigned int signal)
+int test_func(int pid, unsigned int signal)
 {
   M5.Lcd.fillScreen(TFT_DARKGREY);
   M5.Lcd.setCursor(0, 0);
@@ -13,18 +15,28 @@ int test_func(unsigned int signal)
     M5.Lcd.setRotation(3);
     M5.Lcd.print("Initializing...");
   }
-  if (signal & SIGNAL_STOP)
+  if ((signal & SIGNAL_STOP)) // || count == 5)
   {
     M5.Lcd.print("Stopping");
     return 255;
   }
-  if (signal & SIGNAL_TICK)
+  if (signal & SIGNAL_TICK && (signal & SIGNAL_INPUT_A) == 0 && (signal & SIGNAL_INPUT_B) ==0)
   {
     count++;
     M5.Lcd.print("Ran: ");
     M5.Lcd.print(String(count));
     M5.Lcd.print(" times");
   }
+
+  if (signal & SIGNAL_INPUT_A)
+  {
+    M5.Lcd.print("Input A!");
+  }
+  
+  if (signal & SIGNAL_INPUT_B)
+  {
+    M5.Lcd.print("Input B!");
+  }
   return 0;
 }
 
@@ -32,13 +44,13 @@ void setup()
 {
   M5.begin();
   Kernel_setup();
-  PowerManagement_setup();
-
+  //Kernel_start(&PowerManagement, 1000);
+  Kernel_start(&UserInput, 0);
   Kernel_start(&test_func, 1000);
 }
 
 void loop()
 {
+  M5.update();
   Kernel_tick();
-  PowerManagement_tick();
 }