tap: add landing gear capability

This configures the PWM output for the landing gear.

ROMFS/px4fmu_common/mixers/mount_legs.aux.mix

@@ -23,5 +23,5 @@ S: 0 7      0  20000 -10000 -10000  10000
 # mixer for right leg
 M: 1
 O:      10000  10000      0 -10000  10000
-S: 0 8      0  20000 -10000 -10000  10000
+S: 0 7      0  20000 -10000 -10000  10000
 

ROMFS/tap_common/init.d/rcS

@@ -331,10 +331,20 @@ unset OUTPUT_MODE
 #
 # Start the RC input driver
 #
-if fmu mode_rcin
+if fmu mode_pwm1
 then
 fi
 
+#
+# Use 400 Hz PWM output for landing gear (frequency also affects RGB LED)
+#
+pwm rate -c 1 -r 400
+
+#
+# Load the gear mixer onto fmu
+#
+mixer load /dev/px4fmu /etc/mixers/gear.mix
+
 #
 # Start the navigator
 #

ROMFS/tap_common/mixers/gear.mix

@@ -0,0 +1,7 @@
+#
+# This maps actuator_controls_0[7] to the first and only PWM output
+#
+
+M: 1
+O:      10000  10000      0 -10000  10000
+S: 0 7  10000  10000      0 -10000  10000