7 Nokia Corporation - initial contribution. |
7 Nokia Corporation - initial contribution. |
8 Contributors: |
8 Contributors: |
9 --> |
9 --> |
10 <!DOCTYPE concept |
10 <!DOCTYPE concept |
11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
12 <concept id="GUID-F84E18B8-5883-5A3A-A9DB-EC25BB86149F" xml:lang="en"><title>Timers</title><shortdesc>The Kernel implements timing functions using a 1 millisecond tick |
12 <concept id="GUID-F84E18B8-5883-5A3A-A9DB-EC25BB86149F" xml:lang="en"><title>Timers</title><shortdesc>The Kernel implements timing functions using a 1 millisecond |
13 timer.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
13 tick timer.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
14 <p> The phone hardware must therefore provide a high-speed timer that can |
14 <p> The phone hardware must therefore provide a high-speed timer that |
15 provide regular 1 ms interrupts. The ASSP/Variant part of the base port must |
15 can provide regular 1 ms interrupts. The ASSP/Variant part of the |
16 use this timer hardware to call the Kernel every millisecond. </p> |
16 base port must use this timer hardware to call the Kernel every millisecond. </p> |
17 <p>The base port provides the timer service in an interrupt-service routine |
17 <p>The base port provides the timer service in an interrupt-service |
18 called a tick handler. The functions used for this are as follows: </p> |
18 routine called a tick handler. The functions used for this are as |
|
19 follows: </p> |
19 <ul> |
20 <ul> |
20 <li id="GUID-6CFD0FFF-9D8D-5FBC-867C-88933476D896"><p>The tick handler must |
21 <li id="GUID-6CFD0FFF-9D8D-5FBC-867C-88933476D896"><p>The tick handler |
21 be started by the Variant's implementation of the <xref href="GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D.dita#GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D/GUID-FE55E398-7F08-384F-9E74-2CC2E45002B6"><apiname>Asic::Init3()</apiname></xref> function. </p> </li> |
22 must be started by the Variant's implementation of the <xref href="GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D.dita#GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D/GUID-FE55E398-7F08-384F-9E74-2CC2E45002B6"><apiname>Asic::Init3()</apiname></xref> function. </p> </li> |
22 <li id="GUID-9F148C98-2FA8-529D-A0E8-DB5A4705E063"><p>The tick handler calls |
23 <li id="GUID-9F148C98-2FA8-529D-A0E8-DB5A4705E063"><p>The tick handler |
23 the Kernel's <xref href="GUID-C4EB9F55-9A40-3B4D-B90A-FD39A5E68AE1.dita#GUID-C4EB9F55-9A40-3B4D-B90A-FD39A5E68AE1/GUID-BC7CAC2D-97F2-3B82-AF80-7F8535315052"><apiname>NTImer::TickQ()</apiname></xref> function. </p> </li> |
24 calls the Kernel's <xref href="GUID-C4EB9F55-9A40-3B4D-B90A-FD39A5E68AE1.dita#GUID-C4EB9F55-9A40-3B4D-B90A-FD39A5E68AE1/GUID-BC7CAC2D-97F2-3B82-AF80-7F8535315052"><apiname>NTImer::TickQ()</apiname></xref> function. </p> </li> |
24 <li id="GUID-DC16C15E-221B-5945-9F5A-349FAD35921D"><p>The Variant reports |
25 <li id="GUID-DC16C15E-221B-5945-9F5A-349FAD35921D"><p>The Variant |
25 the exact number of microseconds between ticks in its implementation of <xref href="GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D.dita#GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D/GUID-6EAD3751-9F37-3C1B-9910-678A286D80E9"><apiname>Asic::MsTickPeriod()</apiname></xref>. </p> </li> |
26 reports the exact number of microseconds between ticks in its implementation |
|
27 of <xref href="GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D.dita#GUID-A83A7C3C-7DC0-3B9C-842F-70FCC751365D/GUID-6EAD3751-9F37-3C1B-9910-678A286D80E9"><apiname>Asic::MsTickPeriod()</apiname></xref>. </p> </li> |
26 </ul> |
28 </ul> |
27 <p>The ASSP/Variant must decide how to implement a repeating tick interrupt |
29 <p>The ASSP/Variant must decide how to implement a repeating tick |
28 for the hardware available. Typically this involves using either a free running |
30 interrupt for the hardware available. Typically this involves using |
29 timer with a match register, which is reset on each match, or a self-reloading |
31 either a free running timer with a match register, which is reset |
30 countdown timer, to generate a periodic interrupt. </p> |
32 on each match, or a self-reloading countdown timer, to generate a |
|
33 periodic interrupt. </p> |
31 <p>A base port can implement other timers that are required by peripherals |
34 <p>A base port can implement other timers that are required by peripherals |
32 that have sub-millisecond timing requirements. This is optional, and depends |
35 that have sub-millisecond timing requirements. This is optional, and |
33 on the available hardware. </p> |
36 depends on the available hardware. </p> |
34 </conbody><related-links> |
37 </conbody><related-links> |
35 <link href="GUID-E0DCBDCF-C056-53E5-A375-778327F848E4.dita#GUID-E0DCBDCF-C056-53E5-A375-778327F848E4/GUID-F5275882-BBD0-561F-B617-683AA2004BB9"> |
38 <link href="GUID-E0DCBDCF-C056-53E5-A375-778327F848E4.dita#GUID-E0DCBDCF-C056-53E5-A375-778327F848E4/GUID-F5275882-BBD0-561F-B617-683AA2004BB9"> |
36 <linktext>Asic::Init3() implementation</linktext></link> |
39 <linktext>Asic::Init3() implementation</linktext></link> |
37 <link href="http://developer.symbian.org/wiki/index.php/Symbian_OS_Internals/5._Kernel_Services.dita"> |
40 <link href="http://developer.symbian.org/wiki/index.php/Symbian_OS_Internals/5._Kernel_Services" scope="external"><linktext>Symbian OS Internals - Chapter 5.5 Timers</linktext> |
38 <linktext>Symbian OS Internals - Chapter 5.5 Timers</linktext></link> |
41 </link> |
39 </related-links></concept> |
42 </related-links></concept> |