diff --git a/ion/include/ion.h b/ion/include/ion.h
index 2654a0a43..da2313b55 100644
--- a/ion/include/ion.h
+++ b/ion/include/ion.h
@@ -6,6 +6,7 @@
 #include <ion/events.h>
 #include <ion/keyboard.h>
 #include <ion/led.h>
+#include <ion/power.h>
 
 
 /* ION is not your regular library. It is a library you link against, but it
diff --git a/ion/include/ion/power.h b/ion/include/ion/power.h
new file mode 100644
index 000000000..ae4a6747a
--- /dev/null
+++ b/ion/include/ion/power.h
@@ -0,0 +1,12 @@
+#ifndef ION_POWER_H
+#define ION_POWER_H
+
+namespace Ion {
+namespace Power {
+
+void suspend();
+
+}
+}
+
+#endif
diff --git a/ion/src/device/Makefile b/ion/src/device/Makefile
index 4ea83d014..374e40ae0 100644
--- a/ion/src/device/Makefile
+++ b/ion/src/device/Makefile
@@ -6,6 +6,7 @@ objs += $(addprefix ion/src/device/, \
   heap.o\
   keyboard.o\
   led.o\
+  power.o\
 )
 
 # When using the register.h C++ file in production mode, we expect the compiler
diff --git a/ion/src/device/device.cpp b/ion/src/device/device.cpp
index eef8e3fb4..6fe1064ae 100644
--- a/ion/src/device/device.cpp
+++ b/ion/src/device/device.cpp
@@ -53,6 +53,7 @@ void Ion::Device::initClocks() {
   RCC.APB1ENR()->setTIM3EN(true);
 
   RCC.APB2ENR()->setADC1EN(true);
+  RCC.APB2ENR()->setSYSCFGEN(true);
 }
 
 void Ion::Device::initFPU() {
diff --git a/ion/src/device/keyboard.cpp b/ion/src/device/keyboard.cpp
index 7ddb9fe30..89a843a50 100644
--- a/ion/src/device/keyboard.cpp
+++ b/ion/src/device/keyboard.cpp
@@ -79,7 +79,11 @@ bool keyDown(Key k) {
 
 // Private Ion::Keyboard::Device methods
 
-void Ion::Keyboard::Device::init() {
+namespace Ion {
+namespace Keyboard {
+namespace Device {
+
+void init() {
   for (uint8_t i=0; i<numberOfRows; i++) {
     uint8_t pin = RowPins[i];
     RowGPIO.MODER()->setMode(pin, GPIO::MODER::Mode::Output);
@@ -92,3 +96,32 @@ void Ion::Keyboard::Device::init() {
     ColumnGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::Up);
   }
 }
+
+void generateWakeUpEventForKey(Ion::Keyboard::Key k) {
+  // We're driving the rows and reading the columns.
+  int row = rowForKey(k);
+  for (uint8_t i=0; i<numberOfRows; i++) {
+    /* In open-drain mode, a 0 in the register drives the pin low, and a 1 lets
+     * the pin floating (Hi-Z). So we want to set the current row to zero and
+     * all the others to 1. */
+    bool state = (i == row ? 0 : 1);
+    uint8_t pin = RowPins[i];
+    RowGPIO.ODR()->set(pin, state);
+  }
+
+  uint8_t column = columnForKey(k);
+  uint8_t columnPin = ColumnPins[column];
+
+  SYSCFG.EXTICR1()->setEXTI(columnPin, ColumnGPIO);
+
+  EXTI.EMR()->set(columnPin, true);
+
+  /* When the key is pressed, it will go from 1 (because it's pulled up) to
+   * zero (because it's connected to the open-drain output. In other words,
+   * we're waiting for a falling edge. */
+  EXTI.FTSR()->set(columnPin, true);
+}
+
+}
+}
+}
diff --git a/ion/src/device/keyboard.h b/ion/src/device/keyboard.h
index c9c102def..13d79c400 100644
--- a/ion/src/device/keyboard.h
+++ b/ion/src/device/keyboard.h
@@ -1,6 +1,7 @@
 #ifndef ION_DEVICE_KEYBOARD_H
 #define ION_DEVICE_KEYBOARD_H
 
+#include <ion/keyboard.h>
 #include "regs/regs.h"
 
 namespace Ion {
@@ -43,6 +44,8 @@ inline uint8_t columnForKey(Ion::Keyboard::Key key) {
   return (int)key%numberOfColumns;
 }
 
+void generateWakeUpEventForKey(Ion::Keyboard::Key k);
+
 }
 }
 }
diff --git a/ion/src/device/power.cpp b/ion/src/device/power.cpp
new file mode 100644
index 000000000..52a1bb4d1
--- /dev/null
+++ b/ion/src/device/power.cpp
@@ -0,0 +1,10 @@
+#include <ion/power.h>
+#include <ion/display.h>
+#include "keyboard.h"
+
+void Ion::Power::suspend() {
+  Display::setBacklightIntensity(0);
+  Keyboard::Device::generateWakeUpEventForKey(Ion::Keyboard::Key::J1);
+  asm("wfe");
+  Display::setBacklightIntensity(0xFF);
+}
diff --git a/ion/src/device/regs/exti.h b/ion/src/device/regs/exti.h
new file mode 100644
index 000000000..a70a7cfc1
--- /dev/null
+++ b/ion/src/device/regs/exti.h
@@ -0,0 +1,30 @@
+#ifndef REGS_EXTI_H
+#define REGS_EXTI_H
+
+#include "register.h"
+
+class EXTI {
+public:
+  class MaskRegister : Register32 {
+  public:
+    bool get(int index) { return (bool)getBitRange(index, index); }
+    void set(int index, bool state) volatile { setBitRange(index, index, state); }
+  };
+
+  //class IMR : public MaskRegister { };
+  class EMR : public MaskRegister { };
+  class FTSR : public MaskRegister { };
+
+  constexpr EXTI() {};
+  //REGS_REGISTER_AT(IMR, 0x00);
+  REGS_REGISTER_AT(EMR, 0x04);
+  REGS_REGISTER_AT(FTSR, 0x0C);
+private:
+  constexpr uint32_t Base() const {
+    return 0x40013C00;
+  }
+};
+
+constexpr EXTI EXTI;
+
+#endif
diff --git a/ion/src/device/regs/gpio.h b/ion/src/device/regs/gpio.h
index 54535829a..918594473 100644
--- a/ion/src/device/regs/gpio.h
+++ b/ion/src/device/regs/gpio.h
@@ -69,6 +69,7 @@ public:
   };
 
   constexpr GPIO(int i) : m_index(i) {}
+  operator int() const { return m_index; }
   REGS_REGISTER_AT(MODER, 0x00);
   REGS_REGISTER_AT(OTYPER, 0x04);
   REGS_REGISTER_AT(PUPDR, 0x0C);
diff --git a/ion/src/device/regs/rcc.h b/ion/src/device/regs/rcc.h
index 3f2ee432e..5be8b3f3f 100644
--- a/ion/src/device/regs/rcc.h
+++ b/ion/src/device/regs/rcc.h
@@ -36,6 +36,7 @@ public:
   public:
     REGS_BOOL_FIELD(TIM1EN, 0);
     REGS_BOOL_FIELD(ADC1EN, 8);
+    REGS_BOOL_FIELD(SYSCFGEN, 14);
   };
 
   constexpr RCC() {};
diff --git a/ion/src/device/regs/regs.h b/ion/src/device/regs/regs.h
index 209543e1a..586b84e16 100644
--- a/ion/src/device/regs/regs.h
+++ b/ion/src/device/regs/regs.h
@@ -2,10 +2,12 @@
 #define REGS_REGS_H
 
 #include "adc.h"
+#include "exti.h"
 #include "cm4.h"
 #include "fsmc.h"
 #include "rcc.h"
 #include "gpio.h"
+#include "syscfg.h"
 #include "tim.h"
 
 #endif
diff --git a/ion/src/device/regs/syscfg.h b/ion/src/device/regs/syscfg.h
new file mode 100644
index 000000000..c13fbe612
--- /dev/null
+++ b/ion/src/device/regs/syscfg.h
@@ -0,0 +1,25 @@
+#ifndef REGS_SYSCFG_H
+#define REGS_SYSCFG_H
+
+#include "register.h"
+
+#include "gpio.h"
+
+class SYSCFG {
+public:
+  class EXTICR1 : Register32 {
+  public:
+    void setEXTI(int index, GPIO gpio) volatile { setBitRange(4*index+3, 4*index, (uint32_t)gpio); }
+  };
+
+  constexpr SYSCFG() {};
+  REGS_REGISTER_AT(EXTICR1, 0x08);
+private:
+  constexpr uint32_t Base() const {
+    return 0x40013800;
+  }
+};
+
+constexpr SYSCFG SYSCFG;
+
+#endif