AP_Scripting: Add mission selection applet

libraries/AP_Scripting/applets/MissionSelector.lua

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+-- Loads one of three mission files to autopilot on each arm, depending on position of the Mission Reset AUX FUNC switch
+-- Must have Mission Reset switch assigned, it will function normally when armed or disarmed
+-- but also on the disarm to arm transition, it will load (if file exists) a file in the root named
+-- missionH.txt, missionM.txt, or missionH.txt corresponding to the the Mission Reset switch position of High/Mid/Low
+
+local mission_loaded = false
+local rc_switch = rc:find_channel_for_option(24)  --AUX FUNC sw for mission restart
+
+if not rc_switch then  -- requires the switch to be assigned in order to run script
+  return
+end
+
+local function read_mission(file_name)
+
+   -- Open file try and read header
+  local file = io.open(file_name,"r")
+  local header = file:read('l')
+  if not header then
+    return update, 1000 --could not read, file probably does not exist
+  end
+
+  -- check header
+  assert(string.find(header,'QGC WPL 110') == 1, file_name .. ': incorrect format')
+
+  -- clear any existing mission
+  assert(mission:clear(), 'Could not clear current mission')
+
+  -- read each line and write to mission
+  local item = mavlink_mission_item_int_t()
+  local index = 0
+  while true do
+    local data = {}
+    for i = 1, 12 do
+      data[i] = file:read('n')
+      if data[i] == nil then
+        if i == 1 then
+          gcs:send_text(6, 'loaded mission: ' .. file_name)
+          file:close()
+          return -- got to the end of the file
+        else
+          mission:clear() -- clear part loaded mission
+          error('failed to read file')
+        end
+      end
+    end
+
+    item:seq(data[1])
+    item:frame(data[3])
+    item:command(data[4])
+    item:param1(data[5])
+    item:param2(data[6])
+    item:param3(data[7])
+    item:param4(data[8])
+    item:x(data[9]*10^7)
+    item:y(data[10]*10^7)
+    item:z(data[11])
+
+    if not mission:set_item(index,item) then
+      mission:clear() -- clear part loaded mission
+      error(string.format('failed to set mission item %i',index))
+    end
+    index = index + 1
+  end
+  file:close()
+end
+
+function update()
+  if not arming:is_armed() then --if disarmed, wait until armed
+    mission_loaded = false
+    return update,1000
+  end
+  if not mission_loaded then --if first time after arm and switch is valid then try to load based on switch position
+    local filename
+    local sw_pos = rc_switch:get_aux_switch_pos()
+    if sw_pos == 0 then
+        filename = 'missionL.txt'
+    elseif sw_pos == 1 then
+        filename = 'missionM.txt'
+    else
+        filename = 'missionH.txt'
+    end
+    mission_loaded = true
+    read_mission(filename)
+  end
+  return update, 1000
+end
+
+return update, 5000

libraries/AP_Scripting/applets/MissionSelector.md

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+# MissionSelector LUA script
+
+This script will select and load one of three mission files upon every arm depending on the state of the AUX FUNCTION switch for Mission Reset (24). This allows easy, at the field selection of missions, particulary useful for changing autoland/RTL_AUTOLAND directions based on prevailing wing conditions. MissionH.txt, MissionM.txt, or MissionL.txt mission files in the SD card root will be loaded based on that switch position on a disarmed to armed transition.
+
+The basic AUX function of resetting the mission pointer to the first waypoint is unaltered when the switch is moved to the high position, as previous.
+
+If the AUX FUNCTION rc switch is not configured, the script is not active.
+
+If the file selected by the switch position is not in the root SD directory, nothing happens, otherwise the current mission will be cleared and the designated mission file will be loaded and the user notified of the mission change.
+
+If the file is available but is not the correct format , the script will abort.
+
+So a user can install the script and if the switch is configured and a file exists for selection it will function, but either can be missing without causing messaging to the user.