1# RTC<a name="EN-US_TOPIC_0000001051778226"></a> 2 3- [Overview](#section104842041574) 4 - [Available APIs](#section3373340142215) 5 6- [Usage Guidelines](#section20636145604113) 7 - [How to Use](#section16919828134215) 8 - [Creating an RTC Device Handle](#section1131212144310) 9 - [Releasing the RTC Device Handle](#section10744117144314) 10 - [Registering RtcAlarmCallback](#section14839440184320) 11 - [Performing RTC-related Operations](#section161927578433) 12 13- [Usage Example](#section1186111020456) 14 15## Overview<a name="section104842041574"></a> 16 17The real-time clock \(RTC\) driver provides precise real time for the operating system \(OS\). If the OS is powered off, the RTC driver continues to keep track of the system time using an external battery. 18 19### Available APIs<a name="section3373340142215"></a> 20 21**Table 1** APIs provided by the RTC driver 22 23<a name="table1731550155318"></a> 24<table><thead align="left"><tr id="row4419501537"><th class="cellrowborder" valign="top" width="21.902190219021904%" id="mcps1.2.4.1.1"><p id="p641050105320"><a name="p641050105320"></a><a name="p641050105320"></a><strong id="b17744818255"><a name="b17744818255"></a><a name="b17744818255"></a>Capability</strong></p> 25</th> 26<th class="cellrowborder" valign="top" width="24.98249824982498%" id="mcps1.2.4.1.2"><p id="p54150165315"><a name="p54150165315"></a><a name="p54150165315"></a><strong id="b257315114254"><a name="b257315114254"></a><a name="b257315114254"></a>Function</strong></p> 27</th> 28<th class="cellrowborder" valign="top" width="53.11531153115312%" id="mcps1.2.4.1.3"><p id="p941150145313"><a name="p941150145313"></a><a name="p941150145313"></a><strong id="b384185962317"><a name="b384185962317"></a><a name="b384185962317"></a>Description</strong></p> 29</th> 30</tr> 31</thead> 32<tbody><tr id="row17550163418501"><td class="cellrowborder" rowspan="2" valign="top" width="21.902190219021904%" headers="mcps1.2.4.1.1 "><p id="p11670643205012"><a name="p11670643205012"></a><a name="p11670643205012"></a>RTC handle</p> 33</td> 34<td class="cellrowborder" valign="top" width="24.98249824982498%" headers="mcps1.2.4.1.2 "><p id="p16550143465015"><a name="p16550143465015"></a><a name="p16550143465015"></a>RtcOpen</p> 35</td> 36<td class="cellrowborder" valign="top" width="53.11531153115312%" headers="mcps1.2.4.1.3 "><p id="p9550103415015"><a name="p9550103415015"></a><a name="p9550103415015"></a>Opens the RTC device to obtain its handle.</p> 37</td> 38</tr> 39<tr id="row1879052755020"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1479062716506"><a name="p1479062716506"></a><a name="p1479062716506"></a>RtcClose</p> 40</td> 41<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p1579142745012"><a name="p1579142745012"></a><a name="p1579142745012"></a>Releases a specified handle of the RTC device.</p> 42</td> 43</tr> 44<tr id="row34145016535"><td class="cellrowborder" rowspan="2" valign="top" width="21.902190219021904%" headers="mcps1.2.4.1.1 "><p id="p229610227124"><a name="p229610227124"></a><a name="p229610227124"></a>RTC time</p> 45</td> 46<td class="cellrowborder" valign="top" width="24.98249824982498%" headers="mcps1.2.4.1.2 "><p id="p19389143041518"><a name="p19389143041518"></a><a name="p19389143041518"></a>RtcReadTime</p> 47</td> 48<td class="cellrowborder" valign="top" width="53.11531153115312%" headers="mcps1.2.4.1.3 "><p id="p8738101941716"><a name="p8738101941716"></a><a name="p8738101941716"></a>Reads time information from the RTC driver, including the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 49</td> 50</tr> 51<tr id="row5632152611414"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p143890309153"><a name="p143890309153"></a><a name="p143890309153"></a>RtcWriteTime</p> 52</td> 53<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p573815197171"><a name="p573815197171"></a><a name="p573815197171"></a>Writes time information from the RTC driver, including the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 54</td> 55</tr> 56<tr id="row1468016592416"><td class="cellrowborder" rowspan="4" valign="top" width="21.902190219021904%" headers="mcps1.2.4.1.1 "><p id="p36817591648"><a name="p36817591648"></a><a name="p36817591648"></a>RTC alarm</p> 57</td> 58<td class="cellrowborder" valign="top" width="24.98249824982498%" headers="mcps1.2.4.1.2 "><p id="p968116598418"><a name="p968116598418"></a><a name="p968116598418"></a>RtcReadAlarm</p> 59</td> 60<td class="cellrowborder" valign="top" width="53.11531153115312%" headers="mcps1.2.4.1.3 "><p id="p768110592416"><a name="p768110592416"></a><a name="p768110592416"></a>Reads the RTC alarm time that was set last time.</p> 61</td> 62</tr> 63<tr id="row19313155514"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p73141951155"><a name="p73141951155"></a><a name="p73141951155"></a>RtcWriteAlarm</p> 64</td> 65<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p15314656511"><a name="p15314656511"></a><a name="p15314656511"></a>Writes the RTC alarm time based on the alarm index.</p> 66</td> 67</tr> 68<tr id="row138283422555"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p2829142165513"><a name="p2829142165513"></a><a name="p2829142165513"></a>RtcRegisterAlarmCallback</p> 69</td> 70<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p118291242155518"><a name="p118291242155518"></a><a name="p118291242155518"></a>Registers <strong id="b1648234343210"><a name="b1648234343210"></a><a name="b1648234343210"></a>RtcAlarmCallback</strong> that will be invoked when an alarm is generated at the specified time.</p> 71</td> 72</tr> 73<tr id="row13344113914568"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p2344103915616"><a name="p2344103915616"></a><a name="p2344103915616"></a>RtcAlarmInterruptEnable</p> 74</td> 75<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p034415397565"><a name="p034415397565"></a><a name="p034415397565"></a>Enables or disables RTC alarm interrupts.</p> 76</td> 77</tr> 78<tr id="row11801203517565"><td class="cellrowborder" rowspan="3" valign="top" width="21.902190219021904%" headers="mcps1.2.4.1.1 "><p id="p17261458942"><a name="p17261458942"></a><a name="p17261458942"></a>RTC configuration</p> 79</td> 80<td class="cellrowborder" valign="top" width="24.98249824982498%" headers="mcps1.2.4.1.2 "><p id="p15801153515561"><a name="p15801153515561"></a><a name="p15801153515561"></a>RtcGetFreq</p> 81</td> 82<td class="cellrowborder" valign="top" width="53.11531153115312%" headers="mcps1.2.4.1.3 "><p id="p980133515566"><a name="p980133515566"></a><a name="p980133515566"></a>Reads the frequency of the external crystal oscillator connected to the RTC driver.</p> 83</td> 84</tr> 85<tr id="row111502322563"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1615073225618"><a name="p1615073225618"></a><a name="p1615073225618"></a>RtcSetFreq</p> 86</td> 87<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p10150832165613"><a name="p10150832165613"></a><a name="p10150832165613"></a>Sets the frequency of the external crystal oscillator connected to the RTC driver.</p> 88</td> 89</tr> 90<tr id="row21771259145618"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1717725916562"><a name="p1717725916562"></a><a name="p1717725916562"></a>RtcReset</p> 91</td> 92<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p517712598569"><a name="p517712598569"></a><a name="p517712598569"></a>Resets the RTC.</p> 93</td> 94</tr> 95<tr id="row917116425716"><td class="cellrowborder" rowspan="2" valign="top" width="21.902190219021904%" headers="mcps1.2.4.1.1 "><p id="p144765201754"><a name="p144765201754"></a><a name="p144765201754"></a>Custom register</p> 96</td> 97<td class="cellrowborder" valign="top" width="24.98249824982498%" headers="mcps1.2.4.1.2 "><p id="p1117110418570"><a name="p1117110418570"></a><a name="p1117110418570"></a>RtcReadReg</p> 98</td> 99<td class="cellrowborder" valign="top" width="53.11531153115312%" headers="mcps1.2.4.1.3 "><p id="p1517114410578"><a name="p1517114410578"></a><a name="p1517114410578"></a>Reads the configuration of a custom RTC register based on the register index.</p> 100</td> 101</tr> 102<tr id="row46738190576"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1567331910573"><a name="p1567331910573"></a><a name="p1567331910573"></a>RtcWriteReg</p> 103</td> 104<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p1967391913576"><a name="p1967391913576"></a><a name="p1967391913576"></a>Writes the configuration of a custom RTC register based on the register index.</p> 105</td> 106</tr> 107</tbody> 108</table> 109 110> **NOTE:** 111>All functions provided in this document can be called only in kernel mode. 112 113## Usage Guidelines<a name="section20636145604113"></a> 114 115### How to Use<a name="section16919828134215"></a> 116 117During the OS startup, the HDF loads the RTC driver based on the configuration file. The RTC driver detects the RTC component and initializes the driver. 118 119[Figure 1](#fig166181128151112) illustrates the process of using an RTC device. 120 121**Figure 1** Process of using an RTC device<a name="fig166181128151112"></a> 122 123 124 125 126### Creating an RTC Device Handle<a name="section1131212144310"></a> 127 128After the RTC driver is loaded, you can use the API provided by the HDF and call APIs of the RTC driver. 129 130> **NOTE:** 131>Currently, only one RTC device is supported in the OS. 132 133DevHandle RtcOpen\(void\); 134 135**Table 2** Description of RtcOpen 136 137<a name="table1380712985611"></a> 138<table><tbody><tr id="row580722985616"><td class="cellrowborder" valign="top" width="21.45%"><p id="p1280722911565"><a name="p1280722911565"></a><a name="p1280722911565"></a><strong id="b748651620573"><a name="b748651620573"></a><a name="b748651620573"></a>Parameter</strong></p> 139</td> 140<td class="cellrowborder" valign="top" width="78.55%"><p id="p5807112965618"><a name="p5807112965618"></a><a name="p5807112965618"></a><strong id="b08682171578"><a name="b08682171578"></a><a name="b08682171578"></a>Description</strong></p> 141</td> 142</tr> 143<tr id="row17807112935611"><td class="cellrowborder" valign="top" width="21.45%"><p id="p13807132915565"><a name="p13807132915565"></a><a name="p13807132915565"></a>void</p> 144</td> 145<td class="cellrowborder" valign="top" width="78.55%"><p id="p15807429185612"><a name="p15807429185612"></a><a name="p15807429185612"></a>NA</p> 146</td> 147</tr> 148<tr id="row1980782911567"><td class="cellrowborder" valign="top" width="21.45%"><p id="p0807529165613"><a name="p0807529165613"></a><a name="p0807529165613"></a><strong id="b086691895718"><a name="b086691895718"></a><a name="b086691895718"></a>Return Value</strong></p> 149</td> 150<td class="cellrowborder" valign="top" width="78.55%"><p id="p9808162935612"><a name="p9808162935612"></a><a name="p9808162935612"></a><strong id="b6676151975710"><a name="b6676151975710"></a><a name="b6676151975710"></a>Description</strong></p> 151</td> 152</tr> 153<tr id="row2808192935615"><td class="cellrowborder" valign="top" width="21.45%"><p id="p380852915567"><a name="p380852915567"></a><a name="p380852915567"></a>handle</p> 154</td> 155<td class="cellrowborder" valign="top" width="78.55%"><p id="p26881319114110"><a name="p26881319114110"></a><a name="p26881319114110"></a>Returns the if the operation is successful.</p> 156</td> 157</tr> 158<tr id="row4808142945615"><td class="cellrowborder" valign="top" width="21.45%"><p id="p188084291561"><a name="p188084291561"></a><a name="p188084291561"></a>NULL</p> 159</td> 160<td class="cellrowborder" valign="top" width="78.55%"><p id="p780852912566"><a name="p780852912566"></a><a name="p780852912566"></a>The operation fails.</p> 161</td> 162</tr> 163</tbody> 164</table> 165 166``` 167DevHandle handle = NULL; 168 169/* Obtain the RTC device handle. */ 170handle = RtcOpen(); 171if (handle == NULL) { 172 /* Process the error. */ 173} 174``` 175 176### Releasing the RTC Device Handle<a name="section10744117144314"></a> 177 178You can call the following function to release the RTC device handle, thereby releasing resources of the device: 179 180void RtcClose\(DevHandle handle\); 181 182**Table 3** Description of RtcClose 183 184<a name="table37525421510"></a> 185<table><tbody><tr id="row10752134216114"><td class="cellrowborder" valign="top" width="21.45%"><p id="p1075217421019"><a name="p1075217421019"></a><a name="p1075217421019"></a><strong id="b229461765710"><a name="b229461765710"></a><a name="b229461765710"></a>Parameter</strong></p> 186</td> 187<td class="cellrowborder" valign="top" width="78.55%"><p id="p117531421411"><a name="p117531421411"></a><a name="p117531421411"></a><strong id="b2038421875712"><a name="b2038421875712"></a><a name="b2038421875712"></a>Description</strong></p> 188</td> 189</tr> 190<tr id="row57531442914"><td class="cellrowborder" valign="top" width="21.45%"><p id="p8753164210119"><a name="p8753164210119"></a><a name="p8753164210119"></a>handle</p> 191</td> 192<td class="cellrowborder" valign="top" width="78.55%"><p id="p17533425113"><a name="p17533425113"></a><a name="p17533425113"></a>RTC device handle.</p> 193</td> 194</tr> 195</tbody> 196</table> 197 198``` 199/* Release the RTC device handle. */ 200RtcClose(handle); 201``` 202 203### Registering RtcAlarmCallback<a name="section14839440184320"></a> 204 205After the OS is started, call the following function to register **RtcAlarmCallback**, which will be invoked when an alarm is generated at the specified time: 206 207int32\_t RtcRegisterAlarmCallback\(DevHandle handle, enum RtcAlarmIndex alarmIndex, RtcAlarmCallback cb\); 208 209**Table 4** Description of RtcRegisterAlarmCallback 210 211<a name="table7603619123820"></a> 212<table><thead align="left"><tr id="row1060351914386"><th class="cellrowborder" valign="top" width="21.36%" id="mcps1.2.3.1.1"><p id="p14603181917382"><a name="p14603181917382"></a><a name="p14603181917382"></a><strong id="b4295161718571"><a name="b4295161718571"></a><a name="b4295161718571"></a>Parameter</strong></p> 213</th> 214<th class="cellrowborder" valign="top" width="78.64%" id="mcps1.2.3.1.2"><p id="p36031519183819"><a name="p36031519183819"></a><a name="p36031519183819"></a><strong id="b43851218195716"><a name="b43851218195716"></a><a name="b43851218195716"></a>Description</strong></p> 215</th> 216</tr> 217</thead> 218<tbody><tr id="row1181618191115"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p131811218131116"><a name="p131811218131116"></a><a name="p131811218131116"></a>handle</p> 219</td> 220<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p6181191851111"><a name="p6181191851111"></a><a name="p6181191851111"></a>RTC device handle.</p> 221</td> 222</tr> 223<tr id="row960361918383"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p1775535165418"><a name="p1775535165418"></a><a name="p1775535165418"></a>alarmIndex</p> 224</td> 225<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p137551851185412"><a name="p137551851185412"></a><a name="p137551851185412"></a>Alarm index.</p> 226</td> 227</tr> 228<tr id="row1960431983813"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p3604719123817"><a name="p3604719123817"></a><a name="p3604719123817"></a>cb</p> 229</td> 230<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p1560441923818"><a name="p1560441923818"></a><a name="p1560441923818"></a>Callback that will be invoked when an alarm is generated at the specified time.</p> 231</td> 232</tr> 233<tr id="row11410612183019"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p460381915385"><a name="p460381915385"></a><a name="p460381915385"></a><strong id="b132291719185715"><a name="b132291719185715"></a><a name="b132291719185715"></a>Return Value</strong></p> 234</td> 235<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p96031619153812"><a name="p96031619153812"></a><a name="p96031619153812"></a><strong id="b5130182016576"><a name="b5130182016576"></a><a name="b5130182016576"></a>Description</strong></p> 236</td> 237</tr> 238<tr id="row15410111273017"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p133081510112813"><a name="p133081510112813"></a><a name="p133081510112813"></a>0</p> 239</td> 240<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p530813107289"><a name="p530813107289"></a><a name="p530813107289"></a>The operation is successful.</p> 241</td> 242</tr> 243<tr id="row1241081213303"><td class="cellrowborder" valign="top" width="21.36%" headers="mcps1.2.3.1.1 "><p id="p1123362173010"><a name="p1123362173010"></a><a name="p1123362173010"></a>Negative value</p> 244</td> 245<td class="cellrowborder" valign="top" width="78.64%" headers="mcps1.2.3.1.2 "><p id="p1723362153010"><a name="p1723362153010"></a><a name="p1723362153010"></a>The operation fails.</p> 246</td> 247</tr> 248</tbody> 249</table> 250 251The following is an example of registering **RtcAlarmCallback** for processing alarm **RTC\_ALARM\_INDEX\_A**: 252 253``` 254/* Register an RTC alarm callback. */ 255int32_t RtcAlarmACallback(enum RtcAlarmIndex alarmIndex) 256{ 257 if (alarmIndex == RTC_ALARM_INDEX_A) { 258 /* Process alarm A. */ 259 } else if (alarmIndex == RTC_ALARM_INDEX_B) { 260 /* Process alarm B. */ 261 } else { 262 /* Process the error. */ 263 } 264 return 0; 265} 266int32_t ret; 267/* Register RtcAlarmCallback for alarm A. */ 268ret = RtcRegisterAlarmCallback(handle, RTC_ALARM_INDEX_A, RtcAlarmACallback); 269if (ret != 0) { 270 /* Process the error. */ 271} 272``` 273 274### Performing RTC-related Operations<a name="section161927578433"></a> 275 276- Reading RTC time 277 278Call the following function to read time information from the RTC driver, including the year, month, the day of the week, day, hour, minute, second, and millisecond: 279 280int32\_t RtcReadTime\(DevHandle handle, struct RtcTime \*time\); 281 282**Table 5** Description of RtcReadTime 283 284<a name="table1018490043"></a> 285<table><tbody><tr id="row31848013417"><td class="cellrowborder" valign="top" width="21.45%"><p id="p1415816132411"><a name="p1415816132411"></a><a name="p1415816132411"></a><strong id="b10296717125710"><a name="b10296717125710"></a><a name="b10296717125710"></a>Parameter</strong></p> 286</td> 287<td class="cellrowborder" valign="top" width="78.55%"><p id="p11158111316410"><a name="p11158111316410"></a><a name="p11158111316410"></a><strong id="b33873181576"><a name="b33873181576"></a><a name="b33873181576"></a>Description</strong></p> 288</td> 289</tr> 290<tr id="row1246615200297"><td class="cellrowborder" valign="top" width="21.45%"><p id="p188871821142917"><a name="p188871821142917"></a><a name="p188871821142917"></a>handle</p> 291</td> 292<td class="cellrowborder" valign="top" width="78.55%"><p id="p1788742182910"><a name="p1788742182910"></a><a name="p1788742182910"></a>RTC device handle.</p> 293</td> 294</tr> 295<tr id="row10184701945"><td class="cellrowborder" valign="top" width="21.45%"><p id="p104891871157"><a name="p104891871157"></a><a name="p104891871157"></a>time</p> 296</td> 297<td class="cellrowborder" valign="top" width="78.55%"><p id="p204891671156"><a name="p204891671156"></a><a name="p204891671156"></a>Pointer to the time information read from the RTC driver. The time information includes the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 298</td> 299</tr> 300<tr id="row17393154515328"><td class="cellrowborder" valign="top" width="21.45%"><p id="p8158313248"><a name="p8158313248"></a><a name="p8158313248"></a><strong id="b162312198575"><a name="b162312198575"></a><a name="b162312198575"></a>Return Value</strong></p> 301</td> 302<td class="cellrowborder" valign="top" width="78.55%"><p id="p161591413741"><a name="p161591413741"></a><a name="p161591413741"></a><strong id="b3131220165711"><a name="b3131220165711"></a><a name="b3131220165711"></a>Description</strong></p> 303</td> 304</tr> 305<tr id="row339324593215"><td class="cellrowborder" valign="top" width="21.45%"><p id="p139599615287"><a name="p139599615287"></a><a name="p139599615287"></a>0</p> 306</td> 307<td class="cellrowborder" valign="top" width="78.55%"><p id="p1895911611284"><a name="p1895911611284"></a><a name="p1895911611284"></a>The operation is successful.</p> 308</td> 309</tr> 310<tr id="row15393184519323"><td class="cellrowborder" valign="top" width="21.45%"><p id="p13521182309"><a name="p13521182309"></a><a name="p13521182309"></a>Negative value</p> 311</td> 312<td class="cellrowborder" valign="top" width="78.55%"><p id="p1035216186309"><a name="p1035216186309"></a><a name="p1035216186309"></a>The operation fails.</p> 313</td> 314</tr> 315</tbody> 316</table> 317 318``` 319int32_t ret; 320struct RtcTime tm; 321 322/* Read time information from the RTC driver. */ 323ret = RtcReadTime(handle, &tm); 324if (ret != 0) { 325 /* Process the error. */ 326} 327``` 328 329- Setting RTC time 330 331Call the following function to set the RTC time: 332 333int32\_t RtcWriteTime\(DevHandle handle, struct RtcTime \*time\); 334 335**Table 6** Description of RtcWriteTime 336 337<a name="table223910318361"></a> 338<table><tbody><tr id="row924033173613"><td class="cellrowborder" valign="top" width="21.54%"><p id="p16240143143611"><a name="p16240143143611"></a><a name="p16240143143611"></a><strong id="b17297111720576"><a name="b17297111720576"></a><a name="b17297111720576"></a>Parameter</strong></p> 339</td> 340<td class="cellrowborder" valign="top" width="78.46%"><p id="p32401031113610"><a name="p32401031113610"></a><a name="p32401031113610"></a><strong id="b11388191825715"><a name="b11388191825715"></a><a name="b11388191825715"></a>Description</strong></p> 341</td> 342</tr> 343<tr id="row148011248153018"><td class="cellrowborder" valign="top" width="21.54%"><p id="p189641849113018"><a name="p189641849113018"></a><a name="p189641849113018"></a>handle</p> 344</td> 345<td class="cellrowborder" valign="top" width="78.46%"><p id="p20964249123013"><a name="p20964249123013"></a><a name="p20964249123013"></a>RTC device handle.</p> 346</td> 347</tr> 348<tr id="row024043193619"><td class="cellrowborder" valign="top" width="21.54%"><p id="p157679281384"><a name="p157679281384"></a><a name="p157679281384"></a>time</p> 349</td> 350<td class="cellrowborder" valign="top" width="78.46%"><p id="p167675286381"><a name="p167675286381"></a><a name="p167675286381"></a>Pointer to the time information written into the RTC driver. The time information includes the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 351</td> 352</tr> 353<tr id="row424093120369"><td class="cellrowborder" valign="top" width="21.54%"><p id="p1240143114366"><a name="p1240143114366"></a><a name="p1240143114366"></a><strong id="b1023212194579"><a name="b1023212194579"></a><a name="b1023212194579"></a>Return Value</strong></p> 354</td> 355<td class="cellrowborder" valign="top" width="78.46%"><p id="p18241173133619"><a name="p18241173133619"></a><a name="p18241173133619"></a><strong id="b18132142035712"><a name="b18132142035712"></a><a name="b18132142035712"></a>Description</strong></p> 356</td> 357</tr> 358<tr id="row18241531153610"><td class="cellrowborder" valign="top" width="21.54%"><p id="p8550174182810"><a name="p8550174182810"></a><a name="p8550174182810"></a>0</p> 359</td> 360<td class="cellrowborder" valign="top" width="78.46%"><p id="p145503417284"><a name="p145503417284"></a><a name="p145503417284"></a>The operation is successful.</p> 361</td> 362</tr> 363<tr id="row024153123616"><td class="cellrowborder" valign="top" width="21.54%"><p id="p5602191619300"><a name="p5602191619300"></a><a name="p5602191619300"></a>Negative value</p> 364</td> 365<td class="cellrowborder" valign="top" width="78.46%"><p id="p12602131643015"><a name="p12602131643015"></a><a name="p12602131643015"></a>The operation fails.</p> 366</td> 367</tr> 368</tbody> 369</table> 370 371> **NOTE:** 372>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week. 373 374``` 375int32_t ret; 376struct RtcTime tm; 377 378/* Set the RTC time to UTC 2020/01/01 00:59:00 .000. */ 379tm.year = 2020; 380tm.month = 01; 381tm.day = 01; 382tm.hour= 00; 383tm.minute = 59; 384tm.second = 00; 385tm.millisecond = 0; 386/* Write the RTC time information. */ 387ret = RtcWriteTime(handle, &tm); 388if (ret != 0) { 389 /* Process the error. */ 390} 391``` 392 393- Reading the RTC alarm time 394 395Call the following function to read the alarm time: 396 397int32\_t RtcReadAlarm\(DevHandle handle, enum RtcAlarmIndex alarmIndex, struct RtcTime \*time\); 398 399**Table 7** Description of RtcReadAlarm 400 401<a name="table11342203111420"></a> 402<table><tbody><tr id="row133429310140"><td class="cellrowborder" valign="top" width="21.54%"><p id="p9886411201416"><a name="p9886411201416"></a><a name="p9886411201416"></a><strong id="b152971517185720"><a name="b152971517185720"></a><a name="b152971517185720"></a>Parameter</strong></p> 403</td> 404<td class="cellrowborder" valign="top" width="78.46%"><p id="p2886411171417"><a name="p2886411171417"></a><a name="p2886411171417"></a><strong id="b4389418135718"><a name="b4389418135718"></a><a name="b4389418135718"></a>Description</strong></p> 405</td> 406</tr> 407<tr id="row13835647114113"><td class="cellrowborder" valign="top" width="21.54%"><p id="p1183011486412"><a name="p1183011486412"></a><a name="p1183011486412"></a>handle</p> 408</td> 409<td class="cellrowborder" valign="top" width="78.46%"><p id="p1583074815413"><a name="p1583074815413"></a><a name="p1583074815413"></a>RTC device handle.</p> 410</td> 411</tr> 412<tr id="row113439391410"><td class="cellrowborder" valign="top" width="21.54%"><p id="p132281120194318"><a name="p132281120194318"></a><a name="p132281120194318"></a>alarmIndex</p> 413</td> 414<td class="cellrowborder" valign="top" width="78.46%"><p id="p1022852034315"><a name="p1022852034315"></a><a name="p1022852034315"></a>Alarm index.</p> 415</td> 416</tr> 417<tr id="row193431836147"><td class="cellrowborder" valign="top" width="21.54%"><p id="p1926195164011"><a name="p1926195164011"></a><a name="p1926195164011"></a>time</p> 418</td> 419<td class="cellrowborder" valign="top" width="78.46%"><p id="p112695144013"><a name="p112695144013"></a><a name="p112695144013"></a>Pointer to the RTC alarm time information. The time information includes the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 420</td> 421</tr> 422<tr id="row43438361419"><td class="cellrowborder" valign="top" width="21.54%"><p id="p388715117143"><a name="p388715117143"></a><a name="p388715117143"></a><strong id="b14234111985715"><a name="b14234111985715"></a><a name="b14234111985715"></a>Return Value</strong></p> 423</td> 424<td class="cellrowborder" valign="top" width="78.46%"><p id="p088719117143"><a name="p088719117143"></a><a name="p088719117143"></a><strong id="b413222011570"><a name="b413222011570"></a><a name="b413222011570"></a>Description</strong></p> 425</td> 426</tr> 427<tr id="row17169595467"><td class="cellrowborder" valign="top" width="21.54%"><p id="p107751111283"><a name="p107751111283"></a><a name="p107751111283"></a>0</p> 428</td> 429<td class="cellrowborder" valign="top" width="78.46%"><p id="p87751917289"><a name="p87751917289"></a><a name="p87751917289"></a>The operation is successful.</p> 430</td> 431</tr> 432<tr id="row016911915461"><td class="cellrowborder" valign="top" width="21.54%"><p id="p6833213133013"><a name="p6833213133013"></a><a name="p6833213133013"></a>Negative value</p> 433</td> 434<td class="cellrowborder" valign="top" width="78.46%"><p id="p168341213143015"><a name="p168341213143015"></a><a name="p168341213143015"></a>The operation fails.</p> 435</td> 436</tr> 437</tbody> 438</table> 439 440``` 441int32_t ret; 442struct RtcTime alarmTime; 443 444/* Read the RTC alarm time information of alarm RTC_ALARM_INDEX_A. */ 445ret = RtcReadAlarm(handle, RTC_ALARM_INDEX_A, &alarmTime); 446if (ret != 0) { 447 /* Process the error. */ 448} 449``` 450 451- Setting RTC alarm time 452 453Call the following function to set the RTC alarm time based on the alarm index: 454 455int32\_t RtcWriteAlarm\(DevHandle handle, enum RtcAlarmIndex alarmIndex, struct RtcTime \*time\); 456 457**Table 8** Description of RtcWriteAlarm 458 459<a name="table107922162179"></a> 460<table><tbody><tr id="row14793316131710"><td class="cellrowborder" valign="top" width="21.62%"><p id="p1891718412183"><a name="p1891718412183"></a><a name="p1891718412183"></a><strong id="b029811725716"><a name="b029811725716"></a><a name="b029811725716"></a>Parameter</strong></p> 461</td> 462<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p891712461814"><a name="p891712461814"></a><a name="p891712461814"></a><strong id="b1339017181576"><a name="b1339017181576"></a><a name="b1339017181576"></a>Description</strong></p> 463</td> 464</tr> 465<tr id="row18419611133117"><td class="cellrowborder" valign="top" width="21.62%"><p id="p075881210314"><a name="p075881210314"></a><a name="p075881210314"></a>handle</p> 466</td> 467<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p975811215317"><a name="p975811215317"></a><a name="p975811215317"></a>RTC device handle.</p> 468</td> 469</tr> 470<tr id="row11793151613176"><td class="cellrowborder" valign="top" width="21.62%"><p id="p562522145215"><a name="p562522145215"></a><a name="p562522145215"></a>alarmIndex</p> 471</td> 472<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p126257215217"><a name="p126257215217"></a><a name="p126257215217"></a>Alarm index.</p> 473</td> 474</tr> 475<tr id="row37932016201720"><td class="cellrowborder" valign="top" width="21.62%"><p id="p26269212527"><a name="p26269212527"></a><a name="p26269212527"></a>time</p> 476</td> 477<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p462602125211"><a name="p462602125211"></a><a name="p462602125211"></a>Pointer to the RTC alarm time information. The time information includes the year, month, the day of the week, day, hour, minute, second, and millisecond.</p> 478</td> 479</tr> 480<tr id="row586915225485"><td class="cellrowborder" valign="top" width="21.62%"><p id="p591712441810"><a name="p591712441810"></a><a name="p591712441810"></a><strong id="b1923501915574"><a name="b1923501915574"></a><a name="b1923501915574"></a>Return Value</strong></p> 481</td> 482<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1591720461810"><a name="p1591720461810"></a><a name="p1591720461810"></a><strong id="b8133152014571"><a name="b8133152014571"></a><a name="b8133152014571"></a>Description</strong></p> 483</td> 484</tr> 485<tr id="row19869122210483"><td class="cellrowborder" valign="top" width="21.62%"><p id="p10798105812717"><a name="p10798105812717"></a><a name="p10798105812717"></a>0</p> 486</td> 487<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1179817586276"><a name="p1179817586276"></a><a name="p1179817586276"></a>The operation is successful.</p> 488</td> 489</tr> 490<tr id="row1686918225483"><td class="cellrowborder" valign="top" width="21.62%"><p id="p16246181033012"><a name="p16246181033012"></a><a name="p16246181033012"></a>Negative value</p> 491</td> 492<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p3246111019309"><a name="p3246111019309"></a><a name="p3246111019309"></a>The operation fails.</p> 493</td> 494</tr> 495</tbody> 496</table> 497 498> **NOTE:** 499>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week. 500 501``` 502int32_t ret; 503struct RtcTime alarmTime; 504 505/* Set the RTC alarm time to 2020/01/01 00:59:59 .000. */ 506alarmTime.year = 2020; 507alarmTime.month = 01; 508alarmTime.day = 01; 509alarmTime.hour = 00; 510alarmTime.minute = 59; 511alarmTime.second = 59; 512alarmTime.millisecond = 0; 513/* Set the alarm time of alarm RTC_ALARM_INDEX_A. */ 514ret = RtcWriteAlarm(handle, RTC_ALARM_INDEX_A, &alarmTime); 515if (ret != 0) { 516 /* Process the error. */ 517} 518``` 519 520- Enabling or disabling alarm interrupts 521 522Before performing alarm operations, use the following function to enable alarm interrupts, so that **RtcAlarmCallback** will be called when the alarm is not generated upon a timeout: 523 524int32\_t RtcAlarmInterruptEnable\(DevHandle handle, enum RtcAlarmIndex alarmIndex, uint8\_t enable\); 525 526**Table 9** Description of RtcAlarmInterruptEnable 527 528<a name="table1934615314159"></a> 529<table><tbody><tr id="row5346853171519"><td class="cellrowborder" valign="top" width="21.36%"><p id="p143464533153"><a name="p143464533153"></a><a name="p143464533153"></a><strong id="b829913171576"><a name="b829913171576"></a><a name="b829913171576"></a>Parameter</strong></p> 530</td> 531<td class="cellrowborder" valign="top" width="78.64%"><p id="p113461853171514"><a name="p113461853171514"></a><a name="p113461853171514"></a><strong id="b9391318185714"><a name="b9391318185714"></a><a name="b9391318185714"></a>Description</strong></p> 532</td> 533</tr> 534<tr id="row2125652144213"><td class="cellrowborder" valign="top" width="21.36%"><p id="p3150105313422"><a name="p3150105313422"></a><a name="p3150105313422"></a>handle</p> 535</td> 536<td class="cellrowborder" valign="top" width="78.64%"><p id="p9151653144212"><a name="p9151653144212"></a><a name="p9151653144212"></a>RTC device handle.</p> 537</td> 538</tr> 539<tr id="row153794518293"><td class="cellrowborder" valign="top" width="21.36%"><p id="p4259165518294"><a name="p4259165518294"></a><a name="p4259165518294"></a>alarmIndex</p> 540</td> 541<td class="cellrowborder" valign="top" width="78.64%"><p id="p725985522917"><a name="p725985522917"></a><a name="p725985522917"></a>Alarm index.</p> 542</td> 543</tr> 544<tr id="row19346653141518"><td class="cellrowborder" valign="top" width="21.36%"><p id="p6346253101516"><a name="p6346253101516"></a><a name="p6346253101516"></a>enable</p> 545</td> 546<td class="cellrowborder" valign="top" width="78.64%"><p id="p234655341511"><a name="p234655341511"></a><a name="p234655341511"></a>Whether to enable RTC alarm interrupts. The value <strong id="b879021119010"><a name="b879021119010"></a><a name="b879021119010"></a>1</strong> means to enable alarm interrupts and <strong id="b779617111204"><a name="b779617111204"></a><a name="b779617111204"></a>0</strong> means to disable alarm interrupts.</p> 547</td> 548</tr> 549<tr id="row18346953111513"><td class="cellrowborder" valign="top" width="21.36%"><p id="p53460537156"><a name="p53460537156"></a><a name="p53460537156"></a><strong id="b1023631919578"><a name="b1023631919578"></a><a name="b1023631919578"></a>Return Value</strong></p> 550</td> 551<td class="cellrowborder" valign="top" width="78.64%"><p id="p4346153171510"><a name="p4346153171510"></a><a name="p4346153171510"></a><strong id="b7134132075718"><a name="b7134132075718"></a><a name="b7134132075718"></a>Description</strong></p> 552</td> 553</tr> 554<tr id="row1234685314151"><td class="cellrowborder" valign="top" width="21.36%"><p id="p8947195310279"><a name="p8947195310279"></a><a name="p8947195310279"></a>0</p> 555</td> 556<td class="cellrowborder" valign="top" width="78.64%"><p id="p99471953152712"><a name="p99471953152712"></a><a name="p99471953152712"></a>The operation is successful.</p> 557</td> 558</tr> 559<tr id="row2347115321514"><td class="cellrowborder" valign="top" width="21.36%"><p id="p324855163018"><a name="p324855163018"></a><a name="p324855163018"></a>Negative value</p> 560</td> 561<td class="cellrowborder" valign="top" width="78.64%"><p id="p7248857302"><a name="p7248857302"></a><a name="p7248857302"></a>The operation fails.</p> 562</td> 563</tr> 564</tbody> 565</table> 566 567``` 568int32_t ret; 569 570/* Enable the RTC alarm interrupts. */ 571ret = RtcAlarmInterruptEnable(handle, RTC_ALARM_INDEX_A, 1); 572if (ret != 0) { 573 /* Process the error. */ 574} 575``` 576 577- Reading RTC external frequency 578 579Call the following function to read the frequency of the external crystal oscillator connected to the RTC driver: 580 581int32\_t RtcGetFreq\(DevHandle handle, uint32\_t \*freq\); 582 583**Table 10** Description of RtcGetFreq 584 585<a name="table125881625185"></a> 586<table><tbody><tr id="row1458811241816"><td class="cellrowborder" valign="top" width="21.36%"><p id="p658820241813"><a name="p658820241813"></a><a name="p658820241813"></a><strong id="b3300217175712"><a name="b3300217175712"></a><a name="b3300217175712"></a>Parameter</strong></p> 587</td> 588<td class="cellrowborder" valign="top" width="78.64%"><p id="p758812261820"><a name="p758812261820"></a><a name="p758812261820"></a><strong id="b33921718195713"><a name="b33921718195713"></a><a name="b33921718195713"></a>Description</strong></p> 589</td> 590</tr> 591<tr id="row831259124219"><td class="cellrowborder" valign="top" width="21.36%"><p id="p171541407431"><a name="p171541407431"></a><a name="p171541407431"></a>handle</p> 592</td> 593<td class="cellrowborder" valign="top" width="78.64%"><p id="p715413094314"><a name="p715413094314"></a><a name="p715413094314"></a>RTC device handle.</p> 594</td> 595</tr> 596<tr id="row1358842171820"><td class="cellrowborder" valign="top" width="21.36%"><p id="p258814210188"><a name="p258814210188"></a><a name="p258814210188"></a>freq</p> 597</td> 598<td class="cellrowborder" valign="top" width="78.64%"><p id="p165888211810"><a name="p165888211810"></a><a name="p165888211810"></a>Pointer to the frequency to set for the external crystal oscillator, in Hz.</p> 599</td> 600</tr> 601<tr id="row2058818281817"><td class="cellrowborder" valign="top" width="21.36%"><p id="p458872151810"><a name="p458872151810"></a><a name="p458872151810"></a><strong id="b223851915718"><a name="b223851915718"></a><a name="b223851915718"></a>Return Value</strong></p> 602</td> 603<td class="cellrowborder" valign="top" width="78.64%"><p id="p155880251819"><a name="p155880251819"></a><a name="p155880251819"></a><strong id="b0135182045715"><a name="b0135182045715"></a><a name="b0135182045715"></a>Description</strong></p> 604</td> 605</tr> 606<tr id="row35883213183"><td class="cellrowborder" valign="top" width="21.36%"><p id="p8133145211272"><a name="p8133145211272"></a><a name="p8133145211272"></a>0</p> 607</td> 608<td class="cellrowborder" valign="top" width="78.64%"><p id="p13133352202719"><a name="p13133352202719"></a><a name="p13133352202719"></a>The operation is successful.</p> 609</td> 610</tr> 611<tr id="row135892261811"><td class="cellrowborder" valign="top" width="21.36%"><p id="p152692538292"><a name="p152692538292"></a><a name="p152692538292"></a>Negative value</p> 612</td> 613<td class="cellrowborder" valign="top" width="78.64%"><p id="p327015313294"><a name="p327015313294"></a><a name="p327015313294"></a>The operation fails.</p> 614</td> 615</tr> 616</tbody> 617</table> 618 619``` 620int32_t ret; 621uint32_t freq = 0; 622 623/* Read frequency of the external crystal oscillator connected to the RTC driver */ 624ret = RtcGetFreq(handle, &freq); 625if (ret != 0) { 626 /* Process the error. */ 627} 628``` 629 630- Setting the frequency of the external crystal oscillator connected to the RTC driver 631 632Call the following function to set the frequency of the external crystal oscillator connected to the RTC driver: 633 634int32\_t RtcSetFreq\(DevHandle handle, uint32\_t freq\); 635 636**Table 11** Description of RtcSetFreq 637 638<a name="table1170124316209"></a> 639<table><tbody><tr id="row270119432202"><td class="cellrowborder" valign="top" width="21.36%"><p id="p127011343132010"><a name="p127011343132010"></a><a name="p127011343132010"></a><strong id="b130031711578"><a name="b130031711578"></a><a name="b130031711578"></a>Parameter</strong></p> 640</td> 641<td class="cellrowborder" valign="top" width="78.64%"><p id="p7701184372013"><a name="p7701184372013"></a><a name="p7701184372013"></a><strong id="b153942183570"><a name="b153942183570"></a><a name="b153942183570"></a>Description</strong></p> 642</td> 643</tr> 644<tr id="row36067554319"><td class="cellrowborder" valign="top" width="21.36%"><p id="p881511716433"><a name="p881511716433"></a><a name="p881511716433"></a>handle</p> 645</td> 646<td class="cellrowborder" valign="top" width="78.64%"><p id="p188157714432"><a name="p188157714432"></a><a name="p188157714432"></a>RTC device handle.</p> 647</td> 648</tr> 649<tr id="row127019437204"><td class="cellrowborder" valign="top" width="21.36%"><p id="p27019438207"><a name="p27019438207"></a><a name="p27019438207"></a>freq</p> 650</td> 651<td class="cellrowborder" valign="top" width="78.64%"><p id="p167021043182011"><a name="p167021043182011"></a><a name="p167021043182011"></a>Frequency to set for the external crystal oscillator, in Hz</p> 652</td> 653</tr> 654<tr id="row97022434205"><td class="cellrowborder" valign="top" width="21.36%"><p id="p1770218431208"><a name="p1770218431208"></a><a name="p1770218431208"></a><strong id="b18239121916575"><a name="b18239121916575"></a><a name="b18239121916575"></a>Return Value</strong></p> 655</td> 656<td class="cellrowborder" valign="top" width="78.64%"><p id="p1170217432201"><a name="p1170217432201"></a><a name="p1170217432201"></a><strong id="b161361720205713"><a name="b161361720205713"></a><a name="b161361720205713"></a>Description</strong></p> 657</td> 658</tr> 659<tr id="row1670212432206"><td class="cellrowborder" valign="top" width="21.36%"><p id="p77021543152017"><a name="p77021543152017"></a><a name="p77021543152017"></a>0</p> 660</td> 661<td class="cellrowborder" valign="top" width="78.64%"><p id="p770214310209"><a name="p770214310209"></a><a name="p770214310209"></a>The operation is successful.</p> 662</td> 663</tr> 664<tr id="row10702194313201"><td class="cellrowborder" valign="top" width="21.36%"><p id="p165182216306"><a name="p165182216306"></a><a name="p165182216306"></a>Negative value</p> 665</td> 666<td class="cellrowborder" valign="top" width="78.64%"><p id="p651815219302"><a name="p651815219302"></a><a name="p651815219302"></a>The operation fails.</p> 667</td> 668</tr> 669</tbody> 670</table> 671 672``` 673int32_t ret; 674uint32_t freq = 32768; /* 32768 Hz */ 675 676/* Set the frequency of the external crystal oscillator. Note that the frequency must be configured in accordance with the requirements specified in the product manual of the in-use component. */ 677ret = RtcSetFreq(handle, freq); 678if (ret != 0) { 679 /* Process the error. */ 680} 681``` 682 683- Resetting the RTC driver 684 685Call the following function to perform a reset on the RTC driver \(after the reset, the registers are restored to the default values\): 686 687int32\_t RtcReset\(DevHandle handle\); 688 689**Table 12** Description of RtcReset 690 691<a name="table398973152517"></a> 692<table><tbody><tr id="row179899311254"><td class="cellrowborder" valign="top" width="21.36%"><p id="p199899314257"><a name="p199899314257"></a><a name="p199899314257"></a><strong id="b1330101719577"><a name="b1330101719577"></a><a name="b1330101719577"></a>Parameter</strong></p> 693</td> 694<td class="cellrowborder" valign="top" width="78.64%"><p id="p179897315257"><a name="p179897315257"></a><a name="p179897315257"></a><strong id="b9395318115714"><a name="b9395318115714"></a><a name="b9395318115714"></a>Description</strong></p> 695</td> 696</tr> 697<tr id="row14989113118257"><td class="cellrowborder" valign="top" width="21.36%"><p id="p129018136436"><a name="p129018136436"></a><a name="p129018136436"></a>handle</p> 698</td> 699<td class="cellrowborder" valign="top" width="78.64%"><p id="p290111304310"><a name="p290111304310"></a><a name="p290111304310"></a>RTC device handle.</p> 700</td> 701</tr> 702<tr id="row7989123111254"><td class="cellrowborder" valign="top" width="21.36%"><p id="p129894313251"><a name="p129894313251"></a><a name="p129894313251"></a><strong id="b424019198572"><a name="b424019198572"></a><a name="b424019198572"></a>Return Value</strong></p> 703</td> 704<td class="cellrowborder" valign="top" width="78.64%"><p id="p799013112256"><a name="p799013112256"></a><a name="p799013112256"></a><strong id="b913613204578"><a name="b913613204578"></a><a name="b913613204578"></a>Description</strong></p> 705</td> 706</tr> 707<tr id="row9990193142513"><td class="cellrowborder" valign="top" width="21.36%"><p id="p1999043111257"><a name="p1999043111257"></a><a name="p1999043111257"></a>0</p> 708</td> 709<td class="cellrowborder" valign="top" width="78.64%"><p id="p1799093182516"><a name="p1799093182516"></a><a name="p1799093182516"></a>The operation is successful.</p> 710</td> 711</tr> 712<tr id="row16990133152516"><td class="cellrowborder" valign="top" width="21.36%"><p id="p17536173573015"><a name="p17536173573015"></a><a name="p17536173573015"></a>Negative value</p> 713</td> 714<td class="cellrowborder" valign="top" width="78.64%"><p id="p1153623503014"><a name="p1153623503014"></a><a name="p1153623503014"></a>The operation fails.</p> 715</td> 716</tr> 717</tbody> 718</table> 719 720``` 721int32_t ret; 722 723/* Reset the RTC driver. After the reset, the configuration registers are restored to the default values. */ 724ret = RtcReset(handle); 725if (ret != 0) { 726 /* Process the error. */ 727} 728``` 729 730- Reading the configuration of a custom RTC register 731 732Call the following function to read the configuration of a custom RTC register based on the register index \(one index corresponds to one byte of the configuration value\): 733 734int32\_t RtcReadReg\(DevHandle handle, uint8\_t usrDefIndex, uint8\_t \*value\); 735 736**Table 13** Description of RtcReadReg 737 738<a name="table1624674153319"></a> 739<table><tbody><tr id="row92469423320"><td class="cellrowborder" valign="top" width="21.62%"><p id="p102461548331"><a name="p102461548331"></a><a name="p102461548331"></a><strong id="b73024170576"><a name="b73024170576"></a><a name="b73024170576"></a>Parameter</strong></p> 740</td> 741<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p15246847331"><a name="p15246847331"></a><a name="p15246847331"></a><strong id="b1439611818570"><a name="b1439611818570"></a><a name="b1439611818570"></a>Description</strong></p> 742</td> 743</tr> 744<tr id="row171318200434"><td class="cellrowborder" valign="top" width="21.62%"><p id="p9895321184320"><a name="p9895321184320"></a><a name="p9895321184320"></a>handle</p> 745</td> 746<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p68951214436"><a name="p68951214436"></a><a name="p68951214436"></a>RTC device handle.</p> 747</td> 748</tr> 749<tr id="row324614143314"><td class="cellrowborder" valign="top" width="21.62%"><p id="p82466433320"><a name="p82466433320"></a><a name="p82466433320"></a>usrDefIndex</p> 750</td> 751<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p181671825470"><a name="p181671825470"></a><a name="p181671825470"></a>Index of the custom register</p> 752</td> 753</tr> 754<tr id="row524716420334"><td class="cellrowborder" valign="top" width="21.62%"><p id="p8247844333"><a name="p8247844333"></a><a name="p8247844333"></a>value</p> 755</td> 756<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p524711413319"><a name="p524711413319"></a><a name="p524711413319"></a>Pointer to the register value</p> 757</td> 758</tr> 759<tr id="row112471143334"><td class="cellrowborder" valign="top" width="21.62%"><p id="p1124716483312"><a name="p1124716483312"></a><a name="p1124716483312"></a><strong id="b102421419175714"><a name="b102421419175714"></a><a name="b102421419175714"></a>Return Value</strong></p> 760</td> 761<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1524716443313"><a name="p1524716443313"></a><a name="p1524716443313"></a><strong id="b11376206578"><a name="b11376206578"></a><a name="b11376206578"></a>Description</strong></p> 762</td> 763</tr> 764<tr id="row9247194183314"><td class="cellrowborder" valign="top" width="21.62%"><p id="p62476410334"><a name="p62476410334"></a><a name="p62476410334"></a>0</p> 765</td> 766<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p152471433317"><a name="p152471433317"></a><a name="p152471433317"></a>The operation is successful.</p> 767</td> 768</tr> 769<tr id="row1424719410333"><td class="cellrowborder" valign="top" width="21.62%"><p id="p112477417335"><a name="p112477417335"></a><a name="p112477417335"></a>Negative value</p> 770</td> 771<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p7247547338"><a name="p7247547338"></a><a name="p7247547338"></a>The operation fails.</p> 772</td> 773</tr> 774</tbody> 775</table> 776 777``` 778int32_t ret; 779uint8_t usrDefIndex = 0; /* Define index 0 for the first custom register. */ 780uint8_t value = 0; 781 782/* Read the configuration of a custom RTC register based on the register index. One index corresponds to one byte of the configuration value. */ 783ret = RtcReadReg(handle, usrDefIndex, &value); 784if (ret != 0) { 785 /* Process the error. */ 786} 787``` 788 789- Setting the configuration of a custom RTC register 790 791Call the following function to configure a register based on the specified register index \(one index corresponds to one byte of the configuration value\): 792 793int32\_t RtcWriteReg\(DevHandle handle, uint8\_t usrDefIndex, uint8\_t value\); 794 795**Table 14** Description of RtcWriteReg 796 797<a name="table1072216482360"></a> 798<table><tbody><tr id="row187221648133611"><td class="cellrowborder" valign="top" width="21.62%"><p id="p2722184823617"><a name="p2722184823617"></a><a name="p2722184823617"></a><strong id="b530321795712"><a name="b530321795712"></a><a name="b530321795712"></a>Parameter</strong></p> 799</td> 800<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1372374810367"><a name="p1372374810367"></a><a name="p1372374810367"></a><strong id="b1339761865714"><a name="b1339761865714"></a><a name="b1339761865714"></a>Description</strong></p> 801</td> 802</tr> 803<tr id="row1675092612435"><td class="cellrowborder" valign="top" width="21.62%"><p id="p7783927144312"><a name="p7783927144312"></a><a name="p7783927144312"></a>handle</p> 804</td> 805<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p197831427134310"><a name="p197831427134310"></a><a name="p197831427134310"></a>RTC device handle.</p> 806</td> 807</tr> 808<tr id="row1723174815367"><td class="cellrowborder" valign="top" width="21.62%"><p id="p1972364814366"><a name="p1972364814366"></a><a name="p1972364814366"></a>usrDefIndex</p> 809</td> 810<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p18723184819365"><a name="p18723184819365"></a><a name="p18723184819365"></a>Index of the custom register</p> 811</td> 812</tr> 813<tr id="row2723548163611"><td class="cellrowborder" valign="top" width="21.62%"><p id="p1772364893610"><a name="p1772364893610"></a><a name="p1772364893610"></a>value</p> 814</td> 815<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1772324803619"><a name="p1772324803619"></a><a name="p1772324803619"></a>Register value</p> 816</td> 817</tr> 818<tr id="row1072314482361"><td class="cellrowborder" valign="top" width="21.62%"><p id="p6723194853618"><a name="p6723194853618"></a><a name="p6723194853618"></a><strong id="b172432193575"><a name="b172432193575"></a><a name="b172432193575"></a>Return Value</strong></p> 819</td> 820<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p1872314893614"><a name="p1872314893614"></a><a name="p1872314893614"></a><strong id="b131382020165711"><a name="b131382020165711"></a><a name="b131382020165711"></a>Description</strong></p> 821</td> 822</tr> 823<tr id="row20723148173617"><td class="cellrowborder" valign="top" width="21.62%"><p id="p12723348133615"><a name="p12723348133615"></a><a name="p12723348133615"></a>0</p> 824</td> 825<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p472324873620"><a name="p472324873620"></a><a name="p472324873620"></a>The operation is successful.</p> 826</td> 827</tr> 828<tr id="row127231848123615"><td class="cellrowborder" valign="top" width="21.62%"><p id="p197231148173613"><a name="p197231148173613"></a><a name="p197231148173613"></a>Negative value</p> 829</td> 830<td class="cellrowborder" valign="top" width="78.38000000000001%"><p id="p16723134823618"><a name="p16723134823618"></a><a name="p16723134823618"></a>The operation fails.</p> 831</td> 832</tr> 833</tbody> 834</table> 835 836``` 837int32_t ret; 838uint8_t usrDefIndex = 0; /* Define index 0 for the first custom register. */ 839uint8_t value = 0x10; 840 841/* Configure a register based on the specified register index. One index corresponds to one byte of the configuration value. */ 842ret = RtcWriteReg(handle, usrDefIndex, value); 843if (ret != 0) { 844 /* Process the error. */ 845} 846``` 847 848## Usage Example<a name="section1186111020456"></a> 849 850This section describes the process of using RTC APIs: 851 8521. During the OS startup, the HDF identifies the RTC component in the system. 8532. The HDF initializes and creates the RTC device. 8543. You can perform operations on the RTC device by calling different APIs. 8554. Call the **RtcClose** function to release the device handle and device resources. 856 857Example: 858 859``` 860#include "rtc_if.h" 861int32_t RtcAlarmACallback(enum RtcAlarmIndex alarmIndex) 862{ 863 if (alarmIndex == RTC_ALARM_INDEX_A) { 864 /* Process alarm A. */ 865 printf("RTC Alarm A callback function\n\r"); 866 } else if (alarmIndex == RTC_ALARM_INDEX_B) { 867 /* Process alarm B. */ 868 printf("RTC Alarm B callback function\n\r"); 869 } else { 870 /* Process the error. */ 871 } 872 return 0; 873} 874 875void RtcTestSample(void) 876{ 877 int32_t ret; 878 struct RtcTime tm; 879 struct RtcTime alarmTime; 880 uint32_t freq; 881 DevHandle handle = NULL; 882 883 /* Obtain the RTC device handle. */ 884 handle = RtcOpen(); 885 if (handle == NULL) { 886 /* Process the error. */ 887 } 888 /* Register RtcAlarmCallback for alarm A. */ 889 ret = RtcRegisterAlarmCallback(handle, RTC_ALARM_INDEX_A, RtcAlarmACallback); 890 if (ret != 0) { 891 /* Process the error. */ 892 } 893 /* Set the RTC external crystal frequency. Note that the frequency must be configured in accordance with the requirements specified in the product manual of the in-use component. */ 894 freq = 32768; /* 32768 Hz */ 895 ret = RtcSetFreq(handle, freq); 896 if (ret != 0) { 897 /* Process the error. */ 898 } 899 /* Enable the RTC alarm interrupts. */ 900 ret = RtcAlarmInterruptEnable(handle, RTC_ALARM_INDEX_A, 1); 901 if (ret != 0) { 902 /* Process the error. */ 903 } 904 /* Set the RTC time to 2020/01/01 00:00:10 .990. */ 905 tm.year = 2020; 906 tm.month = 01; 907 tm.day = 01; 908 tm.hour= 0; 909 tm.minute = 0; 910 tm.second = 10; 911 tm.millisecond = 990; 912 /* Write the RTC time information. */ 913 ret = RtcWriteTime(handle, &tm); 914 if (ret != 0) { 915 /* Process the error. */ 916 } 917 /* Set the RTC alarm time to 2020/01/01 00:00:30 .100. */ 918 alarmTime.year = 2020; 919 alarmTime.month = 01; 920 alarmTime.day = 01; 921 alarmTime.hour = 0; 922 alarmTime.minute = 0; 923 alarmTime.second = 30; 924 alarmTime.millisecond = 100; 925 /* Set the alarm time information for RTC_ALARM_INDEX_A. When the specified time is reached, "RTC Alarm A callback function" is printed. */ 926 ret = RtcWriteAlarm(handle, RTC_ALARM_INDEX_A, &alarmTime); 927 if (ret != 0) { 928 /* Process the error. */ 929 } 930 931 /* Read the RTC real time. */ 932 ret = RtcReadTime(handle, &tm); 933 if (ret != 0) { 934 /* Process the error. */ 935 } 936 sleep(5) 937 printf("RTC read time:\n\r"); 938 printf("year-month-date-weekday hour:minute:second .millisecond %04u-%02u-%02u-%u %02u:%02u:%02u .%03u", 939 tm.year, tm.month, tm.day, tm.weekday, tm.hour, tm.minute, tm.second, tm.millisecond); 940 /* Release the RTC device handle. */ 941 RtcClose(handle); 942} 943``` 944 945
