1、案例简介
本案例是在小凌派-RK2206开发板上使用IoT库PWM接口，进行PWM编程开发。
例程将创建一个任务，每隔5秒将PWM0~10依次启用，输出1000Hz。
例程源代码：https://gitee.com/Lockzhiner-Electronics/lockzhiner-rk2206-openharmony3.0lts/tree/master/vendor/lockzhiner/rk2206/samples/b16_iot_pwm
2、基础知识
PWM在日常设备中非常常见，以下我们将演示IoT库的PWM接口如何进行PWM控制。
2.1、头文件
base
/
iot_hardware
/
peripheral
/
interfaces
/
kits
/
iot_pwm
.
h
2.2、初始化PWM设备：IoTPwmInit
unsigned
int
IoTPwmInit
(
unsigned
int
port
);
描述：
初始化PWM设备。
参数：
| 参数 | 类型 | 描述 |
|---|---|---|
| port | unsigned int | PWM端口号 |
其中，port对应于如下表所示：
| port | GPIO |
|---|---|
| 0 | GPIO_PB4 |
| 1 | GPIO_PB5 |
| 2 | GPIO_PB6 |
| 3 | GPIO_PC0 |
| 4 | GPIO_PC1 |
| 5 | GPIO_PC2 |
| 6 | GPIO_PC3 |
| 7 | GPIO_PC4 |
| 8 | GPIO_PC5 |
| 9 | GPIO_PC6 |
| 10 | GPIO_PC7 |
返回值：
| 返回值 | 描述 |
|---|---|
| IOT_SUCCESS | 成功 |
| IOT_FAILURE | 失败 |
实现：
hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目录下。
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设备：IoTPwmDeinit
unsigned
int
IoTPwmDeinit
(
unsigned
int
port
);
描述：
取消初始化PWM设备。
参数：
| 参数 | 类型 | 描述 |
|---|---|---|
| port | unsigned int | PWM端口号 |
其中，port对应于如下表所示：
| port | GPIO |
|---|---|
| 0 | GPIO_PB4 |
| 1 | GPIO_PB5 |
| 2 | GPIO_PB6 |
| 3 | GPIO_PC0 |
| 4 | GPIO_PC1 |
| 5 | GPIO_PC2 |
| 6 | GPIO_PC3 |
| 7 | GPIO_PC4 |
| 8 | GPIO_PC5 |
| 9 | GPIO_PC6 |
| 10 | GPIO_PC7 |
返回值：
| 返回值 | 描述 |
|---|---|
| IOT_SUCCESS | 成功 |
| IOT_FAILURE | 失败 |
实现：
hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目录下。
unsigned
int
IoTPwmDeinit
(
unsigned
int
port
)
{
if
(
port
>=
EPWMDEV_MAX
) {
PRINT_ERR
(
"port(%d) >= EPWMDEV_MAX(%d)\n"
port
EPWMDEV_MAX
);
return
IOT_FAILURE
;
}
LzGpioDeinit
(
m_pwm_bus_info
[
port
].
pwm_bus
.
pwm
.
gpio
);
LzPwmDeinit
(
m_pwm_bus_info
[
port
].
port
);
return
IOT_SUCCESS
;
}
2.4、开始PWM信号输出：IoTPwmStart
unsigned
int
IoTPwmStart
(
unsigned
int
port
unsigned
short
duty
unsigned
int
freq
);
描述：
开始PWM信号输出。
参数：
| 参数 | 类型 | 描述 |
|---|---|---|
| port | unsigned int | PWM端口号 |
| duty | unsigned short | 高电平的占空比，范围为1~99 |
| freq | unsigned int | 频率 |
其中，port对应于如下表所示：
| port | GPIO |
|---|---|
| 0 | GPIO_PB4 |
| 1 | GPIO_PB5 |
| 2 | GPIO_PB6 |
| 3 | GPIO_PC0 |
| 4 | GPIO_PC1 |
| 5 | GPIO_PC2 |
| 6 | GPIO_PC3 |
| 7 | GPIO_PC4 |
| 8 | GPIO_PC5 |
| 9 | GPIO_PC6 |
| 10 | GPIO_PC7 |
返回值：
| 返回值 | 描述 |
|---|---|
| IOT_SUCCESS | 成功 |
| IOT_FAILURE | 失败 |
实现：
hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目录下。
unsigned
int
IoTPwmStart
(
unsigned
int
port
unsigned
short
duty
unsigned
int
freq
)
{
#define DUTY_MIN 1
#define DUTY_MAX 99
#define SEC_TO_NSEC (1000000000UL)
unsigned
int
duty_ns
;
unsigned
int
cycle_ns
;
if
(
port
>=
EPWMDEV_MAX
) {
PRINT_ERR
(
"port(%d) >= EPWMDEV_MAX(%d)\n"
port
EPWMDEV_MAX
);
return
IOT_FAILURE
;
}
if
((
duty
<
DUTY_MIN
)
||
(
DUTY_MAX
<
duty
)) {
PRINT_ERR
(
"duty(%d) out of the range(%d ~ %d)\n"
duty
DUTY_MIN
DUTY_MAX
);
return
IOT_FAILURE
;
}
if
(
freq
==
0
) {
PRINT_ERR
(
"freq(%d) is invalid!\n"
freq
);
return
IOT_FAILURE
;
}
if
(
freq
>
SEC_TO_NSEC
) {
PRINT_ERR
(
"freq(%d) > SEC_TO_NSEC(%d)\n"
freq
SEC_TO_NSEC
);
return
IOT_FAILURE
;
}
cycle_ns
=
SEC_TO_NSEC
/
freq
;
duty_ns
=
cycle_ns
*
duty
/
100
;
LzPwmStart
(
m_pwm_bus_info
[
port
].
port
duty_ns
cycle_ns
);
return
IOT_SUCCESS
;
}
2.5、停止PWM信号输出：IoTPwmStop
unsigned
int
IoTPwmStop
(
unsigned
int
port
);
描述：
停止PWM信号输出。
参数：
| 参数 | 类型 | 描述 |
|---|---|---|
| port | unsigned int | PWM端口号 |
其中，port对应于如下表所示：
| port | GPIO |
|---|---|
| 0 | GPIO_PB4 |
| 1 | GPIO_PB5 |
| 2 | GPIO_PB6 |
| 3 | GPIO_PC0 |
| 4 | GPIO_PC1 |
| 5 | GPIO_PC2 |
| 6 | GPIO_PC3 |
| 7 | GPIO_PC4 |
| 8 | GPIO_PC5 |
| 9 | GPIO_PC6 |
| 10 | GPIO_PC7 |
返回值：
| 返回值 | 描述 |
|---|---|
| IOT_SUCCESS | 成功 |
| IOT_FAILURE | 失败 |
实现：
hal_iot_pwm.c文件在device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite目录下。
unsigned
int
IoTPwmStop
(
unsigned
int
port
)
{
if
(
port
>=
EPWMDEV_MAX
) {
PRINT_ERR
(
"port(%d) >= EPWMDEV_MAX(%d)\n"
port
EPWMDEV_MAX
);
return
IOT_FAILURE
;
}
LzPwmStart
(
m_pwm_bus_info
[
port
].
port
0
0
);
return
IOT_SUCCESS
;
}
3、程序设计
在pwm_example函数中，创建一个任务。
void
pwm_example
()
{
unsigned
int
thread_id
;
TSK_INIT_PARAM_S
task
=
{
0
};
unsigned
int
ret
=
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任务中调用IOT库的PWM接口控制PWM。
void
pwm_thread
()
{
unsigned
int
ret
;
/* PWM端口号对应于参考文件：
* device/rockchip/rk2206/adapter/hals/iot_hardware/wifiiot_lite/hal_iot_pwm.c
*/
unsigned
int
port
=
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、编译调试
修改vendor/lockzhiner/rk2206/sample路径下 BUILD.gn 文件，指定iot_pwm_example参与编译。
"./b16_iot_pwm:iot_pwm_example"
修改device/lockzhiner/rk2206/sdk_liteos路径下 Makefile 文件，添加-liot_pwm_example参与编译。
hardware_LIBS
=
-
lhal_iothardware
-
lhardware
-
lshellcmd
-
liot_pwm_example
5、运行结果
示例代码编译烧录代码后，按下开发板的RESET按键，通过串口助手查看日志，任务每隔5s控制不同PWM输出。
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...
