1# Development Guidelines<a name="EN-US_TOPIC_0000001124066545"></a> 2 3- [Available APIs](#section158501652121514) 4- [How to Develop](#section783435801510) 5- [Development Example](#section460018317164) 6 - [Example Description](#section127752801718) 7 - [Sample Code](#section321653551711) 8 - [Verification](#section4366193318167) 9 10 11The time management module provides APIs to implement conversion between the system running time, ticks, and seconds/milliseconds. 12 13## Available APIs<a name="section158501652121514"></a> 14 15The following table describes APIs available for the OpenHarmony LiteOS-M time management. For more details about the APIs, see the API reference. 16 17**Table 1** APIs of the time management module 18 19<a name="table14277123518139"></a> 20<table><thead align="left"><tr id="row152771935131315"><th class="cellrowborder" valign="top" width="17.77177717771777%" id="mcps1.2.4.1.1"><p id="p1127733591316"><a name="p1127733591316"></a><a name="p1127733591316"></a>Category</p> 21</th> 22<th class="cellrowborder" valign="top" width="23.782378237823785%" id="mcps1.2.4.1.2"><p id="p22771357138"><a name="p22771357138"></a><a name="p22771357138"></a>API</p> 23</th> 24<th class="cellrowborder" valign="top" width="58.44584458445845%" id="mcps1.2.4.1.3"><p id="p327714358130"><a name="p327714358130"></a><a name="p327714358130"></a>Description</p> 25</th> 26</tr> 27</thead> 28<tbody><tr id="row1627793517136"><td class="cellrowborder" rowspan="4" valign="top" width="17.77177717771777%" headers="mcps1.2.4.1.1 "><p id="p10525141151410"><a name="p10525141151410"></a><a name="p10525141151410"></a>Time conversion</p> 29</td> 30<td class="cellrowborder" valign="top" width="23.782378237823785%" headers="mcps1.2.4.1.2 "><p id="p1027783551315"><a name="p1027783551315"></a><a name="p1027783551315"></a>LOS_MS2Tick</p> 31</td> 32<td class="cellrowborder" valign="top" width="58.44584458445845%" headers="mcps1.2.4.1.3 "><p id="p1717215119159"><a name="p1717215119159"></a><a name="p1717215119159"></a>Converts milliseconds into ticks.</p> 33</td> 34</tr> 35<tr id="row20278035131316"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p148921018154"><a name="p148921018154"></a><a name="p148921018154"></a>LOS_Tick2MS</p> 36</td> 37<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p61721311101517"><a name="p61721311101517"></a><a name="p61721311101517"></a>Converts ticks into milliseconds.</p> 38</td> 39</tr> 40<tr id="row1736713145208"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p13367171492014"><a name="p13367171492014"></a><a name="p13367171492014"></a>OsCpuTick2MS</p> 41</td> 42<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p14367121422016"><a name="p14367121422016"></a><a name="p14367121422016"></a>Converts cycles into milliseconds. Two UINT32 values indicate the high-order and low-order 32 bits of the result value, respectively.</p> 43</td> 44</tr> 45<tr id="row19475718122016"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p14475121882012"><a name="p14475121882012"></a><a name="p14475121882012"></a>OsCpuTick2US</p> 46</td> 47<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p26621730152310"><a name="p26621730152310"></a><a name="p26621730152310"></a>Converts cycles into microseconds. Two UINT32 values indicate the high-order and low-order 32 bits of the result value, respectively.</p> 48</td> 49</tr> 50<tr id="row327873511316"><td class="cellrowborder" rowspan="3" valign="top" width="17.77177717771777%" headers="mcps1.2.4.1.1 "><p id="p1743134312156"><a name="p1743134312156"></a><a name="p1743134312156"></a>Time statistics</p> 51</td> 52<td class="cellrowborder" valign="top" width="23.782378237823785%" headers="mcps1.2.4.1.2 "><p id="p18278435131316"><a name="p18278435131316"></a><a name="p18278435131316"></a>LOS_SysClockGet</p> 53</td> 54<td class="cellrowborder" valign="top" width="58.44584458445845%" headers="mcps1.2.4.1.3 "><p id="p1827813571317"><a name="p1827813571317"></a><a name="p1827813571317"></a>Obtains the system clock.</p> 55</td> 56</tr> 57<tr id="row1127823541313"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1927810354132"><a name="p1927810354132"></a><a name="p1927810354132"></a>LOS_TickCountGet</p> 58</td> 59<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p17278163512131"><a name="p17278163512131"></a><a name="p17278163512131"></a>Obtains the number of ticks since the system starts.</p> 60</td> 61</tr> 62<tr id="row1027814354131"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1727843510137"><a name="p1727843510137"></a><a name="p1727843510137"></a>LOS_CyclePerTickGet</p> 63</td> 64<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p827819358134"><a name="p827819358134"></a><a name="p827819358134"></a>Obtains the number of cycles for each tick.</p> 65</td> 66</tr> 67</tbody> 68</table> 69 70## How to Develop<a name="section783435801510"></a> 71 72The typical development process of time management is as follows: 73 741. Complete board configuration and adaptation as required, and configure the system clock frequency \(**OS\_SYS\_CLOCK** in Hz and **LOSCFG\_BASE\_CORE\_TICK\_PER\_SECOND**\). The default value of **OS\_SYS\_CLOCK** varies with the hardware platform. 752. Call the clock conversion and statistics APIs. 76 77> **NOTE:** 78>- The time management module depends on **OS\_SYS\_CLOCK** and **LOSCFG\_BASE\_CORE\_TICK\_PER\_SECOND**. 79>- The number of system ticks is not counted when the interrupt feature is disabled. Therefore, the number of ticks cannot be used as the accurate time. 80>- The configuration options are maintained in the **target\_config.h** file of the development board project. 81 82## Development Example<a name="section460018317164"></a> 83 84### Example Description<a name="section127752801718"></a> 85 86The following example describes basic time management methods, including: 87 881. Time conversion: converts milliseconds to ticks or converts ticks to milliseconds. 892. Time statistics: obtains the number of cycles per tick, number of ticks since system startup, and number of delayed ticks. 90 91### Sample Code<a name="section321653551711"></a> 92 93Prerequisites 94 95- The default value of **LOSCFG\_BASE\_CORE\_TICK\_PER\_SECOND** is **100**. 96- The system clock frequency **OS\_SYS\_CLOCK** is configured. 97 98Time conversion: 99 100``` 101VOID Example_TransformTime(VOID) 102{ 103 UINT32 ms; 104 UINT32 tick; 105 106 tick = LOS_MS2Tick(10000); // Convert 10000 ms into ticks. 107 dprintf("tick = %d \n", tick); 108 ms = LOS_Tick2MS(100); // Convert 100 ticks into ms. 109 dprintf("ms = %d \n", ms); 110} 111``` 112 113Time statistics and delay: 114 115``` 116VOID Example_GetTime(VOID) 117{ 118 UINT32 cyclePerTick; 119 UINT64 tickCount; 120 121 cyclePerTick = LOS_CyclePerTickGet(); 122 if(0 != cyclePerTick) { 123 dprintf("LOS_CyclePerTickGet = %d \n", cyclePerTick); 124 } 125 126 tickCount = LOS_TickCountGet(); 127 if(0 != tickCount) { 128 dprintf("LOS_TickCountGet = %d \n", (UINT32)tickCount); 129 } 130 131 LOS_TaskDelay(200); 132 tickCount = LOS_TickCountGet(); 133 if(0 != tickCount) { 134 dprintf("LOS_TickCountGet after delay = %d \n", (UINT32)tickCount); 135 } 136} 137``` 138 139### Verification<a name="section4366193318167"></a> 140 141The development is successful if the return result is as follows: 142 143Time conversion: 144 145``` 146tick = 1000 147ms = 1000 148``` 149 150Time statistics and delay: 151 152``` 153LOS_CyclePerTickGet = 495000 154LOS_TickCountGet = 1 155LOS_TickCountGet after delay = 201 156``` 157 158
