This page details the high-level design behind the autopilot code.
RTOS
The main autopilot systems are built on FreeRTOS, an open-source Real-Time Operating System. FreeRTOS gives us the ability to run multiple concurrent tasks on a single embedded system, each of which has a priority and can "block" for a period of time while they wait for data. At any given time, the highest priority task that is not blocking will be running.
A few notes about developing for real-time systems:
- Treat timeouts as a design error. Most blocking OS functions on the autopilot allow (or require) specifying a timeout for the blocking operation.