# PWM
## 模块介绍
脉冲宽度调制（PWM）是一种对模拟信号电平进行数字编码的方法。通过高分辨率计数器的使用，方波的占空比被调制用来对一个具体模拟信号的电平进行编码。PWM 具有以下特点：
- 支持脉冲（脉冲个数可配）、周期和互补对输出；
- 支持捕捉输入；
- 带可编程死区发生器，死区时间可控；
- 0-24M/100M 输出频率范围、0%-100% 占空比可调、最小分辨率 1/65536；
- 支持 PWM 输出和捕捉输入产生中断；
- 支持 PWM 组模式，同组内各个通道起始相位可配置。
## 模块配置
配置路径如下:
```
Kernel Setup --->
Drivers Setup --->
SoC HAL Drivers --->
pwm devices --->
[*] enable pwm driver
```
## 源码结构
```c
rtos-hal/
|--hal/source/pwm/hal_pwm.c // hal层接口代码
|--include/hal/sunxi_hal_pwm.h // 头文件
```
## 模块接口说明
头文件
```c
#include <sunxi_hal_pwm.h>
```
### 返回值枚举
```c
typedef enum {
HAL_PWM_STATUS_ERROR_PARAMETER = -3,
HAL_PWM_STATUS_ERROR_CHANNEL = -2,
HAL_PWM_STATUS_ERROR = -1,
HAL_PWM_STATUS_OK = 0
} hal_pwm_status_t;
```
### PWM 初始化接口
PWM 模块初始化，主要完成 clk 初始化
函数原型：
```c
pwm_status_t hal_pwm_init(void)
```
参数：
-
返回值：
- 0：成功
- 负数：失败
### PWM 通道配置接口
配置 PWM 模块某个通道，包括周期、占空比和极性
函数原型：
```c
pwm_status_t hal_pwm_control(int channel, struct pwm_config *config_pwm)
```
参数：
- channel 代表通道号
- config_pwm 代表该通道的配置参数
返回值：
- 0：成功
- 负数：失败
### PWM 通道使能接口
使能 PWM 模块某个通道
函数原型：
```c
void hal_pwm_enable_controller(uint32_t channel_in)
```
参数：
- channel_in 代表通道号
返回值：
- 无
### PWM 去初始化接口
PWM 模块去初始化，主要关闭 clk
函数原型：
```c
pwm_status_t hal_pwm_deinit(void)
```
参数：
- 无
返回值：
- 0：成功
- 负数：失败
## 模块使用范例
```c
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <hal_log.h>
#include <hal_cmd.h>
#include <sunxi_hal_pwm.h>
#if defined(CONFIG_ARCH_DSP)
#include <delay.h>
#define sleep(sec) msleep(sec * 1000)
#endif
#ifndef printfFromISR
#define printfFromISR printf
#endif
static int cmd_test_pwm(int argc, char **argv)
{
struct pwm_config *config;
uint8_t port;
//uint8_t ns;
int period, duty;
if (argc < 4)
{
hal_log_info("Usage: pwm port | duty | period\n");
return -1;
}
hal_log_info("Run pwm hal layer test case\n");
port = strtol(argv[1], NULL, 0);
hal_log_info("port = %d", port);
duty = strtoul(argv[2], NULL, 0);
period = strtoul(argv[3], NULL, 0);
config = (struct pwm_config *)malloc(sizeof(struct pwm_config));
config->duty_ns = duty;
config->period_ns = period;
config->polarity = PWM_POLARITY_NORMAL;
hal_log_info("duty_ns = %d \n", config->duty_ns);
hal_log_info("period_ns = %d \n", config->period_ns);
hal_log_info("polarity = %d \n", config->polarity);
hal_pwm_init();
hal_pwm_control(port, config);
hal_log_info("control pwm test finish\n");
return 0;
}
FINSH_FUNCTION_EXPORT_CMD(cmd_test_pwm, hal_pwm, pwm hal APIs tests)
static int cmd_release_pwm_channel(int argc, char **argv)
{
struct pwm_config *config;
uint8_t port;
uint8_t ns;
ulong period, duty;
if (argc < 2)
{
hal_log_info("Usage: pwm port\n");
return -1;
}
hal_log_info("Run close pwm channel test case\n");
port = strtol(argv[1], NULL, 0);
hal_log_info("port = %d", port);
hal_pwm_release(port);
hal_log_info("release pwm channel finish\n");
return 0;
}
FINSH_FUNCTION_EXPORT_CMD(cmd_release_pwm_channel, hal_pwm_close, release pwm channel hal APIs tests)
static void pwm_cap_callback(void* param)
{
hal_pwm_cap_info *info = (hal_pwm_cap_info *)param;
printfFromISR("pwm%d capture callback, cnt is %d, period is %d, duty is %d\n", info->channel, info->cnt, info->period, info->duty);
}
hal_pwm_status_t pwm_capture_init(uint32_t channel)
{
hal_pwm_cap_enable(channel, pwm_cap_callback);
return HAL_PWM_STATUS_OK;
}
hal_pwm_status_t pwm_capture_deinit(uint32_t channel)
{
hal_pwm_cap_disable(channel);
return HAL_PWM_STATUS_OK;
}
void cmd_pwm_capture_help(void)
{
printf("pwm capture test, stop capture after 10s\n");
printf("usage: pwm_capture_test<channel>\n");
printf("\t<channel>: 0 ~ 15\n");
printf("eg: pwm_capture_test 0, pwm0 capture function\n");
}
int cmd_pwm_capture(int argc, char *argv[])
{
int count = 0;
if (argc != 2 || atoi(argv[1]) > 15) {
cmd_pwm_capture_help();
return -1;
}
/* capture setting */
pwm_capture_init(atoi(argv[1]));
for(count = 0; count < 10; count++) {
sleep(1);
}
/* disable */
pwm_capture_deinit(atoi(argv[1]));
printf("[%s]: pwm stop capture ssd\n", __func__);
return 0;
}
FINSH_FUNCTION_EXPORT_CMD(cmd_pwm_capture, pwm_capture_test, pwm capture test)
```
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