diff --git a/y2016/BUILD b/y2016/BUILD
index ccb1315..57892ea 100644
--- a/y2016/BUILD
+++ b/y2016/BUILD
@@ -39,6 +39,7 @@
     '//frc971/autonomous:auto_queue',
     '//y2016/control_loops/shooter:shooter_queue',
     '//y2016/control_loops/superstructure:superstructure_queue',
+    '//y2016/queues:ball_detector',
   ],
 )
 
diff --git a/y2016/joystick_reader.cc b/y2016/joystick_reader.cc
index 0e15eb0..f31b708 100644
--- a/y2016/joystick_reader.cc
+++ b/y2016/joystick_reader.cc
@@ -14,6 +14,7 @@
 #include "frc971/control_loops/drivetrain/drivetrain.q.h"
 #include "y2016/control_loops/shooter/shooter.q.h"
 #include "y2016/control_loops/superstructure/superstructure.q.h"
+#include "y2016/queues/ball_detector.q.h"
 
 #include "y2016/constants.h"
 #include "frc971/queues/gyro.q.h"
@@ -172,7 +173,17 @@
       wrist_goal_ = 0.0;
     }
 
-    is_intaking_ = data.IsPressed(kIntakeIn);
+    bool ball_detected = false;
+    ::y2016::sensors::ball_detector.FetchLatest();
+    if (::y2016::sensors::ball_detector.get()) {
+      ball_detected = ::y2016::sensors::ball_detector->voltage > 2.5;
+    }
+    if (data.PosEdge(kIntakeIn)) {
+      saw_ball_when_started_intaking_ = ball_detected;
+    }
+
+    is_intaking_ = data.IsPressed(kIntakeIn) &&
+                   (!ball_detected || saw_ball_when_started_intaking_);
 
     if (data.IsPressed(kFire) && shooter_velocity_ != 0.0) {
       fire_ = true;
@@ -263,6 +274,9 @@
   // If we're waiting for the subsystems to zero.
   bool waiting_for_zero_ = true;
 
+  // If true, the ball was present when the intaking button was pressed.
+  bool saw_ball_when_started_intaking_ = false;
+
   bool is_intaking_ = false;
   bool is_outtaking_ = false;
   bool fire_ = false;
diff --git a/y2016/queues/BUILD b/y2016/queues/BUILD
index 3b282fd..81f75d4 100644
--- a/y2016/queues/BUILD
+++ b/y2016/queues/BUILD
@@ -3,6 +3,13 @@
 load('/aos/build/queues', 'queue_library')
 
 queue_library(
+  name = 'ball_detector',
+  srcs = [
+    'ball_detector.q',
+  ],
+)
+
+queue_library(
   name = 'profile_params',
   srcs = [
     'profile_params.q',
diff --git a/y2016/queues/ball_detector.q b/y2016/queues/ball_detector.q
new file mode 100644
index 0000000..948cc25
--- /dev/null
+++ b/y2016/queues/ball_detector.q
@@ -0,0 +1,13 @@
+package y2016.sensors;
+
+message BallDetector {
+  // Voltage measured by the ball detector sensor.
+
+  // Higher voltage means ball is closer to detector, lower voltage means ball
+  // is far from the sensor or not in the robot at all.
+  // TODO(comran): Check to see if our sensor's output corresponds with the
+  // comment above.
+
+  double voltage;
+};
+queue BallDetector ball_detector;
diff --git a/y2016/wpilib/BUILD b/y2016/wpilib/BUILD
index bd55575..2cb2937 100644
--- a/y2016/wpilib/BUILD
+++ b/y2016/wpilib/BUILD
@@ -37,5 +37,6 @@
     '//y2016/control_loops/drivetrain:polydrivetrain_plants',
     '//y2016/control_loops/shooter:shooter_queue',
     '//y2016/control_loops/superstructure:superstructure_queue',
+    '//y2016/queues:ball_detector',
   ],
 )
diff --git a/y2016/wpilib/wpilib_interface.cc b/y2016/wpilib/wpilib_interface.cc
index 0ebd0e5..7c58f15 100644
--- a/y2016/wpilib/wpilib_interface.cc
+++ b/y2016/wpilib/wpilib_interface.cc
@@ -36,6 +36,7 @@
 #include "y2016/control_loops/drivetrain/drivetrain_dog_motor_plant.h"
 #include "y2016/control_loops/shooter/shooter.q.h"
 #include "y2016/control_loops/superstructure/superstructure.q.h"
+#include "y2016/queues/ball_detector.q.h"
 
 #include "frc971/wpilib/joystick_sender.h"
 #include "frc971/wpilib/loop_output_handler.h"
@@ -243,6 +244,12 @@
     wrist_encoder_.set_index(::std::move(index));
   }
 
+  // Ball detector setter.
+  void set_ball_detector(::std::unique_ptr<AnalogInput> analog) {
+    ball_detector_ = ::std::move(analog);
+  }
+
+
   // All of the DMA-related set_* calls must be made before this, and it doesn't
   // hurt to do all of them.
 
@@ -333,6 +340,14 @@
 
       superstructure_message.Send();
     }
+
+    {
+      auto ball_detector_message =
+          ::y2016::sensors::ball_detector.MakeMessage();
+      ball_detector_message->voltage = ball_detector_->GetVoltage();
+      LOG_STRUCT(DEBUG, "ball detector", *ball_detector_message);
+      ball_detector_message.Send();
+    }
   }
 
   void Quit() { run_ = false; }
@@ -371,6 +386,7 @@
   ::std::unique_ptr<Encoder> shooter_left_encoder_, shooter_right_encoder_;
   ::frc971::wpilib::DMAEncoderAndPotentiometer intake_encoder_,
       shoulder_encoder_, wrist_encoder_;
+  ::std::unique_ptr<AnalogInput> ball_detector_;
 
   ::std::atomic<bool> run_{true};
   DigitalGlitchFilter drivetrain_shooter_encoder_filter_, hall_filter_,
@@ -611,7 +627,6 @@
     ::std::thread pdp_fetcher_thread(::std::ref(pdp_fetcher));
     SensorReader reader;
 
-    // TODO(constants): Update these input numbers.
     reader.set_drivetrain_left_encoder(make_encoder(5));
     reader.set_drivetrain_right_encoder(make_encoder(6));
     reader.set_drivetrain_left_hall(make_unique<AnalogInput>(5));
@@ -632,6 +647,8 @@
     reader.set_wrist_index(make_unique<DigitalInput>(1));
     reader.set_wrist_potentiometer(make_unique<AnalogInput>(1));
 
+    reader.set_ball_detector(make_unique<AnalogInput>(7));
+
     reader.set_dma(make_unique<DMA>());
     ::std::thread reader_thread(::std::ref(reader));