Meeting real-time constraints using "Sandwich Delays"

In this paper, we are concerned with the development of software for a class of embedded systems in which there are two (sometimes conflicting) constraints. First, we wish to implement the design on a microcontroller with a cost of around $1.00 (US). This type of platform might include an 8-bit or 16/32-bit microcontroller with very limited memory and CPU performance. Second, we wish to produce a system with extremely predictable behaviour. These behavioural constraints are of a hard real-time nature: for example, we typically require that the interval between the start times of periodic tasks does not vary by more than 1 μs (preferably less).