1# UART<a name="ZH-CN_TOPIC_0000001052215244"></a> 2 3- [概述](#section833012453535) 4 - [接口说明](#section1680292311549) 5 6- [使用指导](#section12779050105412) 7 - [使用流程](#section1858116395510) 8 - [获取UART设备句柄](#section124512065617) 9 - [UART设置波特率](#section86881004579) 10 - [UART获取波特率](#section897032965712) 11 - [UART设置设备属性](#section129141884588) 12 - [UART获取设备属性](#section18689637165812) 13 - [设置UART传输模式](#section72713435918) 14 - [向UART设备写入指定长度的数据](#section128001736155919) 15 - [从UART设备中读取指定长度的数据](#section92851601604) 16 - [销毁UART设备句柄](#section1477410521406) 17 18- [使用实例](#section35404241311) 19 20## 概述<a name="section833012453535"></a> 21 22- UART是通用异步收发传输器（Universal Asynchronous Receiver/Transmitter）的缩写，是通用串行数据总线，用于异步通信。该总线双向通信，可以实现全双工传输。 23- UART应用比较广泛，常用于输出打印信息，也可以外接各种模块，如GPS、蓝牙等。 24- 两个UART设备的连接示意图如下，UART与其他模块一般用2线（图1）或4线（图2）相连，它们分别是： 25 - TX：发送数据端，和对端的RX相连； 26 - RX：接收数据端，和对端的TX相连； 27 - RTS：发送请求信号，用于指示本设备是否准备好，可接受数据，和对端CTS相连； 28 - CTS：允许发送信号，用于判断是否可以向对端发送数据，和对端RTS相连； 29 30 **图 1** 2线UART设备连接示意图<a name="fig209936401896"></a> 31 32 33  34 35 **图 2** 4线UART设备连接示意图<a name="fig1435614171015"></a> 36 37 38  39 40 41- UART通信之前，收发双方需要约定好一些参数：波特率、数据格式（起始位、数据位、校验位、停止位）等。通信过程中，UART通过TX发送给对端数据，通过RX接收对端发送的数据。当UART接收缓存达到预定的门限值时，RTS变为不可发送数据，对端的CTS检测到不可发送数据，则停止发送数据。 42- UART接口定义了操作UART端口的通用方法集合，包括获取、释放设备句柄、读写数据、获取和设置波特率、获取和设置设备属性。 43 44### 接口说明<a name="section1680292311549"></a> 45 46**表 1** UART驱动API接口功能介绍 47 48<a name="table1731550155318"></a> 49<table><thead align="left"><tr id="row1223152681611"><th class="cellrowborder" valign="top" width="26.619999999999997%" id="mcps1.2.4.1.1"><p id="p210413571619"><a name="p210413571619"></a><a name="p210413571619"></a>功能分类</p> 50</th> 51<th class="cellrowborder" valign="top" width="31.369999999999997%" id="mcps1.2.4.1.2"><p id="p810403511614"><a name="p810403511614"></a><a name="p810403511614"></a>接口名</p> 52</th> 53<th class="cellrowborder" valign="top" width="42.01%" id="mcps1.2.4.1.3"><p id="p110418354161"><a name="p110418354161"></a><a name="p110418354161"></a>描述</p> 54</th> 55</tr> 56</thead> 57<tbody><tr id="row1638573613415"><td class="cellrowborder" rowspan="2" valign="top" width="26.619999999999997%" headers="mcps1.2.4.1.1 "><p id="p917154316414"><a name="p917154316414"></a><a name="p917154316414"></a>UART获取/释放设备句柄</p> 58<p id="p9596111154212"><a name="p9596111154212"></a><a name="p9596111154212"></a></p> 59</td> 60<td class="cellrowborder" valign="top" width="31.369999999999997%" headers="mcps1.2.4.1.2 "><p id="p20385163614412"><a name="p20385163614412"></a><a name="p20385163614412"></a>UartOpen</p> 61</td> 62<td class="cellrowborder" valign="top" width="42.01%" headers="mcps1.2.4.1.3 "><p id="p12101135184213"><a name="p12101135184213"></a><a name="p12101135184213"></a>UART获取设备句柄</p> 63</td> 64</tr> 65<tr id="row5950143316415"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p149501733134113"><a name="p149501733134113"></a><a name="p149501733134113"></a>UartClose</p> 66</td> 67<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p371073520422"><a name="p371073520422"></a><a name="p371073520422"></a>UART释放设备句柄</p> 68</td> 69</tr> 70<tr id="row34145016535"><td class="cellrowborder" rowspan="2" valign="top" width="26.619999999999997%" headers="mcps1.2.4.1.1 "><p id="p229610227124"><a name="p229610227124"></a><a name="p229610227124"></a>UART读写接口</p> 71<p id="p131072201215"><a name="p131072201215"></a><a name="p131072201215"></a></p> 72</td> 73<td class="cellrowborder" valign="top" width="31.369999999999997%" headers="mcps1.2.4.1.2 "><p id="p8296182221219"><a name="p8296182221219"></a><a name="p8296182221219"></a>UartRead</p> 74</td> 75<td class="cellrowborder" valign="top" width="42.01%" headers="mcps1.2.4.1.3 "><p id="p16297172213125"><a name="p16297172213125"></a><a name="p16297172213125"></a>从UART设备中读取指定长度的数据</p> 76</td> 77</tr> 78<tr id="row11585016539"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1095722493616"><a name="p1095722493616"></a><a name="p1095722493616"></a>UartWrite</p> 79</td> 80<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p15297162215122"><a name="p15297162215122"></a><a name="p15297162215122"></a>向UART设备中写入指定长度的数据</p> 81</td> 82</tr> 83<tr id="row8687115843715"><td class="cellrowborder" rowspan="2" valign="top" width="26.619999999999997%" headers="mcps1.2.4.1.1 "><p id="p196317143813"><a name="p196317143813"></a><a name="p196317143813"></a>UART获取/设置波特率接口</p> 84</td> 85<td class="cellrowborder" valign="top" width="31.369999999999997%" headers="mcps1.2.4.1.2 "><p id="p166885582375"><a name="p166885582375"></a><a name="p166885582375"></a>UartGetBaud</p> 86</td> 87<td class="cellrowborder" valign="top" width="42.01%" headers="mcps1.2.4.1.3 "><p id="p13688358183716"><a name="p13688358183716"></a><a name="p13688358183716"></a>UART获取波特率</p> 88</td> 89</tr> 90<tr id="row18987529382"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p698719214383"><a name="p698719214383"></a><a name="p698719214383"></a>UartSetBaud</p> 91</td> 92<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p1398712123810"><a name="p1398712123810"></a><a name="p1398712123810"></a>UART设置波特率</p> 93</td> 94</tr> 95<tr id="row1551850115317"><td class="cellrowborder" rowspan="2" valign="top" width="26.619999999999997%" headers="mcps1.2.4.1.1 "><p id="p1629782201218"><a name="p1629782201218"></a><a name="p1629782201218"></a>UART获取/设置设备属性</p> 96<p id="p10308192211216"><a name="p10308192211216"></a><a name="p10308192211216"></a></p> 97</td> 98<td class="cellrowborder" valign="top" width="31.369999999999997%" headers="mcps1.2.4.1.2 "><p id="p32972022151218"><a name="p32972022151218"></a><a name="p32972022151218"></a>UartGetAttribute</p> 99</td> 100<td class="cellrowborder" valign="top" width="42.01%" headers="mcps1.2.4.1.3 "><p id="p13297122216123"><a name="p13297122216123"></a><a name="p13297122216123"></a>UART获取设备属性</p> 101</td> 102</tr> 103<tr id="row7545065311"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p102974224120"><a name="p102974224120"></a><a name="p102974224120"></a>UartSetAttribute</p> 104</td> 105<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p152971322111219"><a name="p152971322111219"></a><a name="p152971322111219"></a>UART设置设备属性</p> 106</td> 107</tr> 108<tr id="row14614115403"><td class="cellrowborder" valign="top" width="26.619999999999997%" headers="mcps1.2.4.1.1 "><p id="p1746281144010"><a name="p1746281144010"></a><a name="p1746281144010"></a>UART设置传输模式</p> 109</td> 110<td class="cellrowborder" valign="top" width="31.369999999999997%" headers="mcps1.2.4.1.2 "><p id="p1146215112405"><a name="p1146215112405"></a><a name="p1146215112405"></a>UartSetTransMode</p> 111</td> 112<td class="cellrowborder" valign="top" width="42.01%" headers="mcps1.2.4.1.3 "><p id="p11303181216414"><a name="p11303181216414"></a><a name="p11303181216414"></a>UART设置传输模式</p> 113</td> 114</tr> 115</tbody> 116</table> 117 118> **说明：** 119>本文涉及的所有接口，仅限内核态使用，不支持在用户态使用。 120 121## 使用指导<a name="section12779050105412"></a> 122 123### 使用流程<a name="section1858116395510"></a> 124 125使用UART的一般流程如[图3](#fig1852173020185)所示。 126 127**图 3** UART使用流程图<a name="fig1852173020185"></a> 128 129 130 131 132### 获取UART设备句柄<a name="section124512065617"></a> 133 134在使用UART进行通信时，首先要调用UartOpen获取UART设备句柄，该函数会返回指定端口号的UART设备句柄。 135 136DevHandle UartOpen\(uint32\_t port\); 137 138**表 2** UartOpen参数和返回值描述 139 140<a name="table14222165114310"></a> 141<table><thead align="left"><tr id="row1022175133111"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p13221551153117"><a name="p13221551153117"></a><a name="p13221551153117"></a>参数</p> 142</th> 143<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p122211251103111"><a name="p122211251103111"></a><a name="p122211251103111"></a>参数描述</p> 144</th> 145</tr> 146</thead> 147<tbody><tr id="row6222451133114"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p92221518315"><a name="p92221518315"></a><a name="p92221518315"></a>port</p> 148</td> 149<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1322217518318"><a name="p1322217518318"></a><a name="p1322217518318"></a>UART设备号</p> 150</td> 151</tr> 152<tr id="row1122245153112"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p102221451123118"><a name="p102221451123118"></a><a name="p102221451123118"></a><strong id="b1922235110318"><a name="b1922235110318"></a><a name="b1922235110318"></a>返回值</strong></p> 153</td> 154<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1122215143113"><a name="p1122215143113"></a><a name="p1122215143113"></a><strong id="b19222205193117"><a name="b19222205193117"></a><a name="b19222205193117"></a>返回值描述</strong></p> 155</td> 156</tr> 157<tr id="row522275114317"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p422235114313"><a name="p422235114313"></a><a name="p422235114313"></a>NULL</p> 158</td> 159<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p5222351203112"><a name="p5222351203112"></a><a name="p5222351203112"></a>获取UART设备句柄失败</p> 160</td> 161</tr> 162<tr id="row1222212513311"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p5222125115316"><a name="p5222125115316"></a><a name="p5222125115316"></a>设备句柄</p> 163</td> 164<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p192228515311"><a name="p192228515311"></a><a name="p192228515311"></a>UART设备句柄</p> 165</td> 166</tr> 167</tbody> 168</table> 169 170假设系统中的UART端口号为3，获取该UART设备句柄的示例如下： 171 172``` 173DevHandle handle = NULL; /* UART设备句柄 */ 174uint32_t port = 3; /* UART设备端口号 */ 175handle = UartOpen(port); 176if (handle == NULL) { 177 HDF_LOGE("UartOpen: failed!\n"); 178 return; 179} 180``` 181 182### UART设置波特率<a name="section86881004579"></a> 183 184在通信之前，需要设置UART的波特率，设置波特率的函数如下所示： 185 186int32\_t UartSetBaud\(DevHandle handle, uint32\_t baudRate\); 187 188**表 3** UartSetBaud参数和返回值描述 189 190<a name="table539135313325"></a> 191<table><thead align="left"><tr id="row15391205311323"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p11390453103216"><a name="p11390453103216"></a><a name="p11390453103216"></a>参数</p> 192</th> 193<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p839065316328"><a name="p839065316328"></a><a name="p839065316328"></a>参数描述</p> 194</th> 195</tr> 196</thead> 197<tbody><tr id="row2039115373216"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p1639165310324"><a name="p1639165310324"></a><a name="p1639165310324"></a>handle</p> 198</td> 199<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p539115320328"><a name="p539115320328"></a><a name="p539115320328"></a>UART设备句柄</p> 200</td> 201</tr> 202<tr id="row163911753143214"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p13911653203215"><a name="p13911653203215"></a><a name="p13911653203215"></a>baudRate</p> 203</td> 204<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p163919537322"><a name="p163919537322"></a><a name="p163919537322"></a>待设置的波特率值</p> 205</td> 206</tr> 207<tr id="row539155343218"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p1039185313321"><a name="p1039185313321"></a><a name="p1039185313321"></a><strong id="b139195343217"><a name="b139195343217"></a><a name="b139195343217"></a>返回值</strong></p> 208</td> 209<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p123911753143213"><a name="p123911753143213"></a><a name="p123911753143213"></a><strong id="b143911353163218"><a name="b143911353163218"></a><a name="b143911353163218"></a>返回值描述</strong></p> 210</td> 211</tr> 212<tr id="row2391853153218"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p17391185310322"><a name="p17391185310322"></a><a name="p17391185310322"></a>0</p> 213</td> 214<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p14391653193210"><a name="p14391653193210"></a><a name="p14391653193210"></a>UART设置波特率成功</p> 215</td> 216</tr> 217<tr id="row23912053143211"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p7391165320321"><a name="p7391165320321"></a><a name="p7391165320321"></a>负数</p> 218</td> 219<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p639185318322"><a name="p639185318322"></a><a name="p639185318322"></a>UART设置波特率失败</p> 220</td> 221</tr> 222</tbody> 223</table> 224 225假设需要设置的UART波特率为9600，设置波特率的实例如下： 226 227``` 228int32_t ret; 229/* 设置UART波特率 */ 230ret = UartSetBaud(handle, 9600); 231if (ret != 0) { 232 HDF_LOGE("UartSetBaud: failed, ret %d\n", ret); 233} 234``` 235 236### UART获取波特率<a name="section897032965712"></a> 237 238设置UART的波特率后，可以通过获取波特率接口来查看UART当前的波特率，获取波特率的函数如下所示： 239 240int32\_t UartGetBaud\(DevHandle handle, uint32\_t \*baudRate\); 241 242**表 4** UartGetBaud参数和返回值描述 243 244<a name="table20393185311326"></a> 245<table><thead align="left"><tr id="row19392653123215"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p6392105315326"><a name="p6392105315326"></a><a name="p6392105315326"></a>参数</p> 246</th> 247<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p53920531329"><a name="p53920531329"></a><a name="p53920531329"></a>参数描述</p> 248</th> 249</tr> 250</thead> 251<tbody><tr id="row103921553103211"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p1539220536326"><a name="p1539220536326"></a><a name="p1539220536326"></a>handle</p> 252</td> 253<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p6392553203217"><a name="p6392553203217"></a><a name="p6392553203217"></a>UART设备句柄</p> 254</td> 255</tr> 256<tr id="row1539211532322"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p93921053123210"><a name="p93921053123210"></a><a name="p93921053123210"></a>baudRate</p> 257</td> 258<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p93926536328"><a name="p93926536328"></a><a name="p93926536328"></a>接收波特率值的指针</p> 259</td> 260</tr> 261<tr id="row1239318531326"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p17392653123213"><a name="p17392653123213"></a><a name="p17392653123213"></a><strong id="b3392165383219"><a name="b3392165383219"></a><a name="b3392165383219"></a>返回值</strong></p> 262</td> 263<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1339365316327"><a name="p1339365316327"></a><a name="p1339365316327"></a><strong id="b63932053183218"><a name="b63932053183218"></a><a name="b63932053183218"></a>返回值描述</strong></p> 264</td> 265</tr> 266<tr id="row143939531328"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p2393953153213"><a name="p2393953153213"></a><a name="p2393953153213"></a>0</p> 267</td> 268<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p8393165383218"><a name="p8393165383218"></a><a name="p8393165383218"></a>UART获取波特率成功</p> 269</td> 270</tr> 271<tr id="row5393105363210"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p17393125363215"><a name="p17393125363215"></a><a name="p17393125363215"></a>负数</p> 272</td> 273<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1539325393211"><a name="p1539325393211"></a><a name="p1539325393211"></a>UART获取波特率失败</p> 274</td> 275</tr> 276</tbody> 277</table> 278 279获取波特率的实例如下： 280 281``` 282int32_t ret; 283uint32_t baudRate; 284/* 获取UART波特率 */ 285ret = UartGetBaud(handle, &baudRate); 286if (ret != 0) { 287 HDF_LOGE("UartGetBaud: failed, ret %d\n", ret); 288} 289``` 290 291### UART设置设备属性<a name="section129141884588"></a> 292 293在通信之前，需要设置UART的设备属性，设置设备属性的函数如下图所示： 294 295int32\_t UartSetAttribute\(DevHandle handle, struct UartAttribute \*attribute\)； 296 297**表 5** UartSetAttribute参数和返回值描述 298 299<a name="table1453119335341"></a> 300<table><thead align="left"><tr id="row3530433103416"><th class="cellrowborder" valign="top" width="49.980000000000004%" id="mcps1.2.3.1.1"><p id="p1853073310341"><a name="p1853073310341"></a><a name="p1853073310341"></a>参数</p> 301</th> 302<th class="cellrowborder" valign="top" width="50.019999999999996%" id="mcps1.2.3.1.2"><p id="p553083393417"><a name="p553083393417"></a><a name="p553083393417"></a>参数描述</p> 303</th> 304</tr> 305</thead> 306<tbody><tr id="row55303331347"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p1530113313341"><a name="p1530113313341"></a><a name="p1530113313341"></a>handle</p> 307</td> 308<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p3530173313346"><a name="p3530173313346"></a><a name="p3530173313346"></a>UART设备句柄</p> 309</td> 310</tr> 311<tr id="row45309337342"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p553083319348"><a name="p553083319348"></a><a name="p553083319348"></a>attribute</p> 312</td> 313<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p5530133314343"><a name="p5530133314343"></a><a name="p5530133314343"></a>待设置的设备属性</p> 314</td> 315</tr> 316<tr id="row12530833103415"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p185309331345"><a name="p185309331345"></a><a name="p185309331345"></a><strong id="b145302033193410"><a name="b145302033193410"></a><a name="b145302033193410"></a>返回值</strong></p> 317</td> 318<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p145309332344"><a name="p145309332344"></a><a name="p145309332344"></a><strong id="b553018331348"><a name="b553018331348"></a><a name="b553018331348"></a>返回值描述</strong></p> 319</td> 320</tr> 321<tr id="row14530203310348"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p1653014339343"><a name="p1653014339343"></a><a name="p1653014339343"></a>0</p> 322</td> 323<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p1453023323419"><a name="p1453023323419"></a><a name="p1453023323419"></a>UART设置设备属性成功</p> 324</td> 325</tr> 326<tr id="row6531163373412"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p16530123310345"><a name="p16530123310345"></a><a name="p16530123310345"></a>负数</p> 327</td> 328<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p1953118334347"><a name="p1953118334347"></a><a name="p1953118334347"></a>UART设置设备属性失败</p> 329</td> 330</tr> 331</tbody> 332</table> 333 334设置UART的设备属性的实例如下： 335 336``` 337int32_t ret; 338struct UartAttribute attribute; 339attribute.dataBits = UART_ATTR_DATABIT_7; /* UART传输数据位宽，一次传输7个bit */ 340attribute.parity = UART_ATTR_PARITY_NONE; /* UART传输数据无校检 */ 341attribute.stopBits = UART_ATTR_STOPBIT_1; /* UART传输数据停止位为1位 */ 342attribute.rts = UART_ATTR_RTS_DIS; /* UART禁用RTS */ 343attribute.cts = UART_ATTR_CTS_DIS; /* UART禁用CTS */ 344attribute.fifoRxEn = UART_ATTR_RX_FIFO_EN; /* UART使能RX FIFO */ 345attribute.fifoTxEn = UART_ATTR_TX_FIFO_EN; /* UART使能TX FIFO */ 346/* 设置UART设备属性 */ 347ret = UartSetAttribute(handle, &attribute); 348if (ret != 0) { 349 HDF_LOGE("UartSetAttribute: failed, ret %d\n", ret); 350} 351``` 352 353### UART获取设备属性<a name="section18689637165812"></a> 354 355设置UART的设备属性后，可以通过获取设备属性接口来查看UART当前的设备属性，获取设备属性的函数如下图所示： 356 357int32\_t UartGetAttribute\(DevHandle handle, struct UartAttribute \*attribute\); 358 359**表 6** UartGetAttribute参数和返回值描述 360 361<a name="table17532123316342"></a> 362<table><thead align="left"><tr id="row18531193383420"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p85311833143420"><a name="p85311833143420"></a><a name="p85311833143420"></a>参数</p> 363</th> 364<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p17531103319348"><a name="p17531103319348"></a><a name="p17531103319348"></a>参数描述</p> 365</th> 366</tr> 367</thead> 368<tbody><tr id="row35311533153413"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p453133333418"><a name="p453133333418"></a><a name="p453133333418"></a>handle</p> 369</td> 370<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p753193323420"><a name="p753193323420"></a><a name="p753193323420"></a>UART设备句柄</p> 371</td> 372</tr> 373<tr id="row1953103315344"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p35315333346"><a name="p35315333346"></a><a name="p35315333346"></a>attribute</p> 374</td> 375<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p14531633133416"><a name="p14531633133416"></a><a name="p14531633133416"></a>接收UART设备属性的指针</p> 376</td> 377</tr> 378<tr id="row45321433143415"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p653273363417"><a name="p653273363417"></a><a name="p653273363417"></a><strong id="b19531153314349"><a name="b19531153314349"></a><a name="b19531153314349"></a>返回值</strong></p> 379</td> 380<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1653203312347"><a name="p1653203312347"></a><a name="p1653203312347"></a><strong id="b185321330348"><a name="b185321330348"></a><a name="b185321330348"></a>返回值描述</strong></p> 381</td> 382</tr> 383<tr id="row175320339342"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p10532163383412"><a name="p10532163383412"></a><a name="p10532163383412"></a>0</p> 384</td> 385<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p5532143319341"><a name="p5532143319341"></a><a name="p5532143319341"></a>UART获取设备属性成功</p> 386</td> 387</tr> 388<tr id="row125327337340"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p19532153317345"><a name="p19532153317345"></a><a name="p19532153317345"></a>负数</p> 389</td> 390<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p175321933163410"><a name="p175321933163410"></a><a name="p175321933163410"></a>UART获取设备属性失败</p> 391</td> 392</tr> 393</tbody> 394</table> 395 396获取UART的设备属性的实例如下： 397 398``` 399int32_t ret; 400struct UartAttribute attribute; 401/* 获取UART设备属性 */ 402ret = UartGetAttribute(handle, &attribute); 403if (ret != 0) { 404 HDF_LOGE("UartGetAttribute: failed, ret %d\n", ret); 405} 406``` 407 408### 设置UART传输模式<a name="section72713435918"></a> 409 410在通信之前，需要设置UART的传输模式，设置传输模式的函数如下图所示： 411 412int32\_t UartSetTransMode\(DevHandle handle, enum UartTransMode mode\)； 413 414**表 7** UartSetTransMode参数和返回值描述 415 416<a name="table131892266313"></a> 417<table><thead align="left"><tr id="row018922615318"><th class="cellrowborder" valign="top" width="49.980000000000004%" id="mcps1.2.3.1.1"><p id="p131891826835"><a name="p131891826835"></a><a name="p131891826835"></a>参数</p> 418</th> 419<th class="cellrowborder" valign="top" width="50.019999999999996%" id="mcps1.2.3.1.2"><p id="p101894269314"><a name="p101894269314"></a><a name="p101894269314"></a>参数描述</p> 420</th> 421</tr> 422</thead> 423<tbody><tr id="row11893261734"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p81897261333"><a name="p81897261333"></a><a name="p81897261333"></a>handle</p> 424</td> 425<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p5190142618310"><a name="p5190142618310"></a><a name="p5190142618310"></a>UART设备句柄</p> 426</td> 427</tr> 428<tr id="row1119082615317"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p1519012261314"><a name="p1519012261314"></a><a name="p1519012261314"></a>mode</p> 429</td> 430<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p121901026632"><a name="p121901026632"></a><a name="p121901026632"></a>待设置的传输模式，</p> 431</td> 432</tr> 433<tr id="row19190152612317"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p131900266316"><a name="p131900266316"></a><a name="p131900266316"></a><strong id="b61902026833"><a name="b61902026833"></a><a name="b61902026833"></a>返回值</strong></p> 434</td> 435<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p1519022616315"><a name="p1519022616315"></a><a name="p1519022616315"></a><strong id="b319014261837"><a name="b319014261837"></a><a name="b319014261837"></a>返回值描述</strong></p> 436</td> 437</tr> 438<tr id="row919016261932"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p10190526334"><a name="p10190526334"></a><a name="p10190526334"></a>0</p> 439</td> 440<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p1219012264318"><a name="p1219012264318"></a><a name="p1219012264318"></a>UART设置传输模式成功</p> 441</td> 442</tr> 443<tr id="row1219017262313"><td class="cellrowborder" valign="top" width="49.980000000000004%" headers="mcps1.2.3.1.1 "><p id="p15190162616316"><a name="p15190162616316"></a><a name="p15190162616316"></a>负数</p> 444</td> 445<td class="cellrowborder" valign="top" width="50.019999999999996%" headers="mcps1.2.3.1.2 "><p id="p131906262311"><a name="p131906262311"></a><a name="p131906262311"></a>UART设置传输模式失败</p> 446</td> 447</tr> 448</tbody> 449</table> 450 451假设需要设置的UART传输模式为UART\_MODE\_RD\_BLOCK，设置传输模式的实例如下： 452 453``` 454int32_t ret; 455/* 设置UART传输模式 */ 456ret = UartSetTransMode(handle, UART_MODE_RD_BLOCK); 457if (ret != 0) { 458 HDF_LOGE("UartSetTransMode: failed, ret %d\n", ret); 459} 460``` 461 462### 向UART设备写入指定长度的数据<a name="section128001736155919"></a> 463 464对应的接口函数如下所示： 465 466int32\_t UartWrite\(DevHandle handle, uint8\_t \*data, uint32\_t size\); 467 468**表 8** UartWrite参数和返回值描述 469 470<a name="table27825111368"></a> 471<table><thead align="left"><tr id="row1578171123619"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p078112115360"><a name="p078112115360"></a><a name="p078112115360"></a>参数</p> 472</th> 473<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p37811711163612"><a name="p37811711163612"></a><a name="p37811711163612"></a>参数描述</p> 474</th> 475</tr> 476</thead> 477<tbody><tr id="row1878291143611"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p07818112360"><a name="p07818112360"></a><a name="p07818112360"></a>handle</p> 478</td> 479<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p178281113369"><a name="p178281113369"></a><a name="p178281113369"></a>UART设备句柄</p> 480</td> 481</tr> 482<tr id="row7782811123614"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p8782911173610"><a name="p8782911173610"></a><a name="p8782911173610"></a>data</p> 483</td> 484<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p17782171120366"><a name="p17782171120366"></a><a name="p17782171120366"></a>待写入数据的指针</p> 485</td> 486</tr> 487<tr id="row1578251112367"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p3782911183612"><a name="p3782911183612"></a><a name="p3782911183612"></a>size</p> 488</td> 489<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p17782161110366"><a name="p17782161110366"></a><a name="p17782161110366"></a>待写入数据的长度</p> 490</td> 491</tr> 492<tr id="row1378281113363"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p87821411183616"><a name="p87821411183616"></a><a name="p87821411183616"></a><strong id="b157825113363"><a name="b157825113363"></a><a name="b157825113363"></a>返回值</strong></p> 493</td> 494<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p13782111116361"><a name="p13782111116361"></a><a name="p13782111116361"></a><strong id="b978211113366"><a name="b978211113366"></a><a name="b978211113366"></a>返回值描述</strong></p> 495</td> 496</tr> 497<tr id="row47822112365"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p107821011103613"><a name="p107821011103613"></a><a name="p107821011103613"></a>0</p> 498</td> 499<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p11782191103610"><a name="p11782191103610"></a><a name="p11782191103610"></a>UART写数据成功</p> 500</td> 501</tr> 502<tr id="row11782911113611"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p1578221111367"><a name="p1578221111367"></a><a name="p1578221111367"></a>负数</p> 503</td> 504<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p9782151110366"><a name="p9782151110366"></a><a name="p9782151110366"></a>UART写数据失败</p> 505</td> 506</tr> 507</tbody> 508</table> 509 510写入指定长度数据的实例如下： 511 512``` 513int32_t ret; 514uint8_t wbuff[5] = {1, 2, 3, 4, 5}; 515/* 向UART设备写入指定长度的数据 */ 516ret = UartWrite(handle, wbuff, 5); 517if (ret != 0) { 518 HDF_LOGE("UartWrite: failed, ret %d\n", ret); 519} 520``` 521 522### 从UART设备中读取指定长度的数据<a name="section92851601604"></a> 523 524对应的接口函数如下所示： 525 526int32\_t UartRead\(DevHandle handle, uint8\_t \*data, uint32\_t size\); 527 528**表 9** UartRead参数和返回值描述 529 530<a name="table162341717123713"></a> 531<table><thead align="left"><tr id="row023313171377"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p1123331710376"><a name="p1123331710376"></a><a name="p1123331710376"></a>参数</p> 532</th> 533<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p523321783715"><a name="p523321783715"></a><a name="p523321783715"></a>参数描述</p> 534</th> 535</tr> 536</thead> 537<tbody><tr id="row6234417133712"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p7233121716379"><a name="p7233121716379"></a><a name="p7233121716379"></a>handle</p> 538</td> 539<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p17234101753712"><a name="p17234101753712"></a><a name="p17234101753712"></a>UART设备句柄</p> 540</td> 541</tr> 542<tr id="row18234151718372"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p16234191783711"><a name="p16234191783711"></a><a name="p16234191783711"></a>data</p> 543</td> 544<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p923417175378"><a name="p923417175378"></a><a name="p923417175378"></a>接收读取数据的指针</p> 545</td> 546</tr> 547<tr id="row82341017193711"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p13234917103717"><a name="p13234917103717"></a><a name="p13234917103717"></a>size</p> 548</td> 549<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p182341817153717"><a name="p182341817153717"></a><a name="p182341817153717"></a>待读取数据的长度</p> 550</td> 551</tr> 552<tr id="row102341617123717"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p172341617163712"><a name="p172341617163712"></a><a name="p172341617163712"></a><strong id="b1323411179373"><a name="b1323411179373"></a><a name="b1323411179373"></a>返回值</strong></p> 553</td> 554<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p1623431763718"><a name="p1623431763718"></a><a name="p1623431763718"></a><strong id="b1123411173377"><a name="b1123411173377"></a><a name="b1123411173377"></a>返回值描述</strong></p> 555</td> 556</tr> 557<tr id="row4234151719372"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p3234131716375"><a name="p3234131716375"></a><a name="p3234131716375"></a>非负数</p> 558</td> 559<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p7234171783718"><a name="p7234171783718"></a><a name="p7234171783718"></a>UART读取到的数据长度</p> 560</td> 561</tr> 562<tr id="row112340173378"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p1423431743714"><a name="p1423431743714"></a><a name="p1423431743714"></a>负数</p> 563</td> 564<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p32349178378"><a name="p32349178378"></a><a name="p32349178378"></a>UART读取数据失败</p> 565</td> 566</tr> 567</tbody> 568</table> 569 570读取指定长度数据的实例如下： 571 572``` 573int32_t ret; 574uint8_t rbuff[5] = {0}; 575/* 从UART设备读取指定长度的数据 */ 576ret = UartRead(handle, rbuff, 5); 577if (ret < 0) { 578 HDF_LOGE("UartRead: failed, ret %d\n", ret); 579} 580``` 581 582> **注意：** 583>UART返回值为非负值，表示UART读取成功。若返回值等于0，表示UART无有效数据可以读取。若返回值大于0，表示实际读取到的数据长度，该长度小于或等于传入的参数size的大小，并且不超过当前正在使用的UART控制器规定的最大单次读取数据长度的值。 584 585### 销毁UART设备句柄<a name="section1477410521406"></a> 586 587UART通信完成之后，需要销毁UART设备句柄，函数如下所示： 588 589void UartClose\(DevHandle handle\); 590 591该函数会释放申请的资源。 592 593**表 10** UartClose参数和返回值描述 594 595<a name="table03348317351"></a> 596<table><thead align="left"><tr id="row15334837351"><th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.1"><p id="p933411316354"><a name="p933411316354"></a><a name="p933411316354"></a>参数</p> 597</th> 598<th class="cellrowborder" valign="top" width="50%" id="mcps1.2.3.1.2"><p id="p16334103143517"><a name="p16334103143517"></a><a name="p16334103143517"></a>参数描述</p> 599</th> 600</tr> 601</thead> 602<tbody><tr id="row733483103513"><td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.1 "><p id="p7334530358"><a name="p7334530358"></a><a name="p7334530358"></a>handle</p> 603</td> 604<td class="cellrowborder" valign="top" width="50%" headers="mcps1.2.3.1.2 "><p id="p133341331356"><a name="p133341331356"></a><a name="p133341331356"></a>UART设备句柄</p> 605</td> 606</tr> 607</tbody> 608</table> 609 610销毁UART设备句柄的实例如下： 611 612``` 613UartClose(handle); /* 销毁UART设备句柄 * 614``` 615 616## 使用实例<a name="section35404241311"></a> 617 618UART设备完整的使用示例如下所示，首先获取UART设备句柄，接着设置波特率、设备属性和传输模式，之后进行UART通信，最后销毁UART设备句柄。 619 620``` 621#include "hdf_log.h" 622#include "uart_if.h" 623 624void UartTestSample(void) 625{ 626 int32_t ret; 627 uint32_t port; 628 DevHandle handle = NULL; 629 uint8_t wbuff[5] = { 1, 2, 3, 4, 5 }; 630 uint8_t rbuff[5] = { 0 }; 631 struct UartAttribute attribute; 632 attribute.dataBits = UART_ATTR_DATABIT_7; /* UART传输数据位宽，一次传输7个bit */ 633 attribute.parity = UART_ATTR_PARITY_NONE; /* UART传输数据无校检 */ 634 attribute.stopBits = UART_ATTR_STOPBIT_1; /* UART传输数据停止位为1位 */ 635 attribute.rts = UART_ATTR_RTS_DIS; /* UART禁用RTS */ 636 attribute.cts = UART_ATTR_CTS_DIS; /* UART禁用CTS */ 637 attribute.fifoRxEn = UART_ATTR_RX_FIFO_EN; /* UART使能RX FIFO */ 638 attribute.fifoTxEn = UART_ATTR_TX_FIFO_EN; /* UART使能TX FIFO */ 639 /* UART设备端口号，要填写实际平台上的端口号 */ 640 port = 1; 641 /* 获取UART设备句柄 */ 642 handle = UartOpen(port); 643 if (handle == NULL) { 644 HDF_LOGE("UartOpen: failed!\n"); 645 return; 646 } 647 /* 设置UART波特率为9600 */ 648 ret = UartSetBaud(handle, 9600); 649 if (ret != 0) { 650 HDF_LOGE("UartSetBaud: failed, ret %d\n", ret); 651 goto _ERR; 652 } 653 /* 设置UART设备属性 */ 654 ret = UartSetAttribute(handle, &attribute); 655 if (ret != 0) { 656 HDF_LOGE("UartSetAttribute: failed, ret %d\n", ret); 657 goto _ERR; 658 } 659 /* 设置UART传输模式为非阻塞模式 */ 660 ret = UartSetTransMode(handle, UART_MODE_RD_NONBLOCK); 661 if (ret != 0) { 662 HDF_LOGE("UartSetTransMode: failed, ret %d\n", ret); 663 goto _ERR; 664 } 665 /* 向UART设备写入5字节的数据 */ 666 ret = UartWrite(handle, wbuff, 5); 667 if (ret != 0) { 668 HDF_LOGE("UartWrite: failed, ret %d\n", ret); 669 goto _ERR; 670 } 671 /* 从UART设备读取5字节的数据 */ 672 ret = UartRead(handle, rbuff, 5); 673 if (ret < 0) { 674 HDF_LOGE("UartRead: failed, ret %d\n", ret); 675 goto _ERR; 676 } 677_ERR: 678 /* 销毁UART设备句柄 */ 679 UartClose(handle); 680} 681``` 682 683
