Embedded Systems: An Integrated Approach by Pearson

252 EMBEDDED SYSTEMS

In the OS, interrupts are used either with hardware support (provided by the

processor) or by pure software. Either way, an interrupt handler or ISR does the

processing of the task initiated by the interrupt. In multitasking systems, task switching

is usually accomplished by interrupts. For example, in the round robin method, every

tseconds, an interrupt is generated and then the current task is pre-empted and the next

task is taken up.

Interrupts are associated with a delay which is called ‘interrupt latency’. Recollect

the sequence of actions that follow an interrupt, which are as follows:

i) Saving the current context

ii) Determining the identity of the interrupt

iii) Switching to the new context

iv) Starting ...