got the output check stuff actually compiling and closer to working
diff --git a/bbb_cape/src/cape/data_struct.h b/bbb_cape/src/cape/data_struct.h
index d60a0e9..6d747bb 100644
--- a/bbb_cape/src/cape/data_struct.h
+++ b/bbb_cape/src/cape/data_struct.h
@@ -82,9 +82,12 @@
       int32_t left_drive;
       int32_t right_drive;
 
-      // The length of the pulse from the ultrasonic sensor in 100kHZ ticks.
+      // The length of the pulse from the ultrasonic sensor in 100KHz ticks.
       uint32_t ultrasonic_pulse_length;
 
+      // The length of the pulse from the sidecar PWM output in 10MHz ticks.
+      uint32_t output_check_pulse_length;
+
       int32_t shooter_position, pusher_distal_posedge_position,
           pusher_proximal_posedge_position;