AP_Scripting: Add EFI state get example

libraries/AP_Scripting/examples/efi_speed_check.lua

@@ -0,0 +1,21 @@
+--[[
+    Example for getting state of EFI and checking if the RPM is within tolerance
+--]]
+
+function do_check()
+    local efi_state = efi:get_state()
+    local engine_speed = efi_state:engine_speed_rpm()
+    if not engine_speed then
+        return
+    end
+    if engine_speed > 7000 then
+        gcs:send_text(2, "ECU RPM is too high!")
+    end
+end
+
+function update()
+    do_check()
+    return update, 100
+end
+gcs:send_text(6, "Started EFI speed check");
+return update, 0