We're working on getting MISSION_ITEM_INT into APM master, and there is one outstanding issue that looks to be blocking at the moment. The current protocol doesn't offer any way to request what type of mission item a component is expecting from any transaction. Any feedback on how to address this?
There are currently two proposed solutions:
The current WIP PR can be found here: https://github.com/ArduPilot/ardupilot/pull/3937 It uses the second approach, the PR for the MAVLink side is available here: https://github.com/ArduPilot/mavlink/pull/3 (the doc string is slightly wrong and needs to be fixed before it's pulled in).