Sync with the PWM signal

Change-Id: I8f625c42e31b504744ce5b506fc8689370406402
diff --git a/y2020/wpilib_interface.cc b/y2020/wpilib_interface.cc
index 8c30918..4275506 100644
--- a/y2020/wpilib_interface.cc
+++ b/y2020/wpilib_interface.cc
@@ -481,6 +481,7 @@
     // Thread 3.
     ::aos::ShmEventLoop sensor_reader_event_loop(&config.message());
     SensorReader sensor_reader(&sensor_reader_event_loop);
+    sensor_reader.set_pwm_trigger(true);
     sensor_reader.set_drivetrain_left_encoder(make_encoder(0));
     sensor_reader.set_drivetrain_right_encoder(make_encoder(1));
     // TODO: pin numbers