Embedded Systems Design, 2nd Edition

Real-time without a RTOS 405

long time will loose their time accuracy. The tick is not that

accurate and the system time will quickly gain or lose time

compared to the time maintained by the real-time clock. Each time

the PC is rebooted, the system time is reset to match the real-time

clock and the accumulated error removed.

There is an already defined interrupt routine for this in the

PC. By programming the timer to generate a different time period

tick and then intercepting the interrupt handler and passing

control to the data sampler software, accurate timing for the data

sampling can be achieved. This is the basic method used in the

design.

Sampling ...