Embedded Systems Design, 2nd Edition

192 Embedded systems design

To convert the previous example to one using interrupts, all

the polling and data port code is removed from the background

analysis software. The data transfer code is written as part of the

interrupt service routine (ISR) associated with the interrupt gen-

erated by the data port hardware. When the port receives a byte of

data, it generates an interrupt. This activates the ISR which proc-

esses the data before handing execution back to the background

task. The beauty of this type of operation is that the background

task can be written independently of the data port code and that

the whole timing of the system is now moved ...