1、案例簡介

本案例是在小凌派-RK2206開發板上使用IoT庫PWM接口，進行PWM編程開發。

例程將創建一個任務，每隔5秒將PWM0~10依次啟用，輸出1000Hz。

例程源代碼：https://gitee.com/Lockzhiner-Electronics/lockzhiner-rk2206-openharmony3.0lts/tree/master/vendor/lockzhiner/rk2206/samples/b16_iot_pwm

2、基礎知識

PWM在日常設備中非常常見，以下我們將演示IoT庫的PWM接口如何進行PWM控制。

2.1、頭文件

base/iot_hardware/peripheral/interfaces/kits/iot_pwm.h

2.2、初始化PWM設備：IoTPwmInit

unsignedintIoTPwmInit(unsignedintport);

描述：

初始化PWM設備。

參數：

其中，port對應于如下表所示：

返回值：

實現：

hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目錄下。

unsignedintIoTPwmInit(unsignedintport){ unsignedintret =0; if(port >= EPWMDEV_MAX) { PRINT_ERR("port(%d) >= EPWMDEV_MAX(%d)\n", port, EPWMDEV_MAX); returnIOT_FAILURE; } PinctrlSet(m_pwm_bus_info[port].pwm_bus.pwm.gpio, m_pwm_bus_info[port].pwm_bus.pwm.func, m_pwm_bus_info[port].pwm_bus.pwm.type, m_pwm_bus_info[port].pwm_bus.pwm.drv); PwmIoInit(m_pwm_bus_info[port].pwm_bus); LzPwmInit(m_pwm_bus_info[port].port); returnIOT_SUCCESS;}

2.3、取消初始化PWM設備：IoTPwmDeinit

unsignedintIoTPwmDeinit(unsignedintport);

描述：

取消初始化PWM設備。

參數：

其中，port對應于如下表所示：

返回值：

實現：

hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目錄下。

unsignedintIoTPwmDeinit(unsignedintport)
{
if(port>=EPWMDEV_MAX) {
PRINT_ERR("port(%d) >= EPWMDEV_MAX(%d)\n",port,EPWMDEV_MAX);
returnIOT_FAILURE;
}

LzGpioDeinit(m_pwm_bus_info[port].pwm_bus.pwm.gpio);

LzPwmDeinit(m_pwm_bus_info[port].port);

returnIOT_SUCCESS;
}

2.4、開始PWM信號輸出：IoTPwmStart

unsignedintIoTPwmStart(unsignedintport,unsignedshortduty,unsignedintfreq);

描述：

開始PWM信號輸出。

參數：

其中，port對應于如下表所示：

返回值：

實現：

hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目錄下。

unsignedintIoTPwmStart(unsignedintport,unsignedshortduty,unsignedintfreq)
{
#define DUTY_MIN 1
#define DUTY_MAX 99
#define SEC_TO_NSEC (1000000000UL)
unsignedintduty_ns;
unsignedintcycle_ns;

if(port>=EPWMDEV_MAX) {
PRINT_ERR("port(%d) >= EPWMDEV_MAX(%d)\n",port,EPWMDEV_MAX);
returnIOT_FAILURE;
}
if((duty<DUTY_MIN)||(DUTY_MAX<duty)) {
PRINT_ERR("duty(%d) out of the range(%d ~ %d)\n",duty,DUTY_MIN,DUTY_MAX);
returnIOT_FAILURE;
}
if(freq==0) {
PRINT_ERR("freq(%d) is invalid!\n",freq);
returnIOT_FAILURE;
}
if(freq>SEC_TO_NSEC) {
PRINT_ERR("freq(%d) > SEC_TO_NSEC(%d)\n",freq,SEC_TO_NSEC);
returnIOT_FAILURE;
}

cycle_ns=SEC_TO_NSEC/freq;
duty_ns=cycle_ns*duty/100;

LzPwmStart(m_pwm_bus_info[port].port,duty_ns,cycle_ns);

returnIOT_SUCCESS;
}

2.5、停止PWM信號輸出：IoTPwmStop

unsignedintIoTPwmStop(unsignedintport);

描述：

停止PWM信號輸出。

參數：

其中，port對應于如下表所示：

返回值：

實現：

hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目錄下。

unsignedintIoTPwmStop(unsignedintport)
{
if(port>=EPWMDEV_MAX) {
PRINT_ERR("port(%d) >= EPWMDEV_MAX(%d)\n",port,EPWMDEV_MAX);
returnIOT_FAILURE;
}

LzPwmStart(m_pwm_bus_info[port].port,0,0);

returnIOT_SUCCESS;
}

3、程序設計

在pwm_example函數中，創建一個任務。

voidpwm_example()
{
unsignedintthread_id;
TSK_INIT_PARAM_Stask={0};
unsignedintret =LOS_OK;

task.pfnTaskEntry=(TSK_ENTRY_FUNC)pwm_thread;
task.uwStackSize =2048;
task.pcName ="pwm_thread";
task.usTaskPrio =20;
ret =LOS_TaskCreate(&thread_id,&task);
if(ret!=LOS_OK) {
printf("Falied to create pwm_thread ret:0x%x\n",ret);
return;
}
}

pwm_thread任務中調用IOT庫的PWM接口控制PWM。

voidpwm_thread()
{
unsignedintret;
/* PWM端口號對應于參考文件：
* device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite/hal_iot_pwm.c
*/
unsignedintport=0;

while(1) {
printf("===========================\n");
printf("PWM(%d) Init\n",port);
ret=IoTPwmInit(port);
if(ret!=0) {
printf("IoTPwmInit failed(%d)\n");
continue;
}

printf("PWM(%d) Start\n",port);
ret=IoTPwmStart(port,50,1000);
if(ret!=0) {
printf("IoTPwmStart failed(%d)\n");
continue;
}

LOS_Msleep(5000);

printf("PWM(%d) end\n",port);
ret=IoTPwmStop(port);
if(ret!=0) {
printf("IoTPwmStop failed(%d)\n");
continue;
}

ret=IoTPwmDeinit(port);
if(ret!=0) {
printf("IoTPwmInit failed(%d)\n");
continue;
}

printf("\n");

port++;
if(port>=11) {
port=0;
}
}
}

4、編譯調試

修改vendor/lockzhiner/rk2206/sample路徑下 BUILD.gn 文件，指定iot_pwm_example參與編譯。

"./b16_iot_pwm:iot_pwm_example",

修改device/lockzhiner/rk2206/sdk_liteos路徑下 Makefile 文件，添加-liot_pwm_example參與編譯。

hardware_LIBS=-lhal_iothardware-lhardware-lshellcmd-liot_pwm_example

5、運行結果

示例代碼編譯燒錄代碼后，按下開發板的RESET按鍵，通過串口助手查看日志，任務每隔5s控制不同PWM輸出。

entering kernelinit...hilog willinit.[MAIN:D]Main: LOS_Start ...Entering schedulerOHOS# hiview init success.===========================PWM(0) Init[GPIO:D]LzGpioInit: id12isinitialized successfullyPWM(0) StartPWM(0) end[GPIO:D]LzGpioDeinit: id 12isreleased successfully===========================PWM(1) Init[GPIO:D]LzGpioInit: id13isinitialized successfullyPWM(1) StartPWM(1) end[GPIO:D]LzGpioDeinit: id 13isreleased successfully...