In summary, there are three BIOS modules that are concerned with timing services. The timer module takes control of one of the device’s timer peripherals. This module plugs the peripheral’s interrupt with it’s own ISR and provides a service where it can fire an application function. The clock module can use some external periodic event in the system as an input  that calls the Clock_doTick() API, or can be configured to use a periodic heartbeat from the SYS/BIOS timer module. This module creates a software interrupt which gets posted by one of the inputs and enables any number of functions to be configured to fire, either as one shots or periodically. The timestamp module can provide a very powerful way to do benchmarks on the user’s code and help with debugging using the real time analysis tools.