Timers

diff -r 578be2adaf3e -r 307f4279f433 Adaptation/GUID-F84E18B8-5883-5A3A-A9DB-EC25BB86149F.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Adaptation/GUID-F84E18B8-5883-5A3A-A9DB-EC25BB86149F.dita Fri Oct 15 14:32:18 2010 +0100 @@ -0,0 +1,42 @@ + + + + + +TimersThe kernel implements timing functions using a 1 millisecond +tick timer. +

The phone hardware must therefore provide a high-speed timer that +can provide regular 1 ms interrupts. The ASSP/Variant part of the +base port must use this timer hardware to call the kernel every millisecond.

The base port provides the timer service in an interrupt-service +routine called a tick handler. The functions used for this are as +follows:

The tick handler +must be started by the Variant's implementation of the Asic::Init3() function.
The tick handler +calls the kernel's NTImer::TickQ() function.
The Variant +reports the exact number of microseconds between ticks in its implementation +of Asic::MsTickPeriod().

The ASSP/Variant must decide how to implement a repeating tick +interrupt for the hardware available. Typically this involves using +either a free running timer with a match register, which is reset +on each match, or a self-reloading countdown timer, to generate a +periodic interrupt.

A base port can implement other timers that are required by peripherals +that have sub-millisecond timing requirements. This is optional, and +depends on the available hardware.

+ +Asic::Init3() implementation +Symbian OS Internals - Chapter 5.5 Timers + +

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