RT-Thread-【NXP-MCXA153】PWM驱动移植RT-Thread问答社区

【NXP-MCXA153】PWM驱动移植

发布于 2024-07-25 22:14:36 浏览：189 订阅该版

[tocm]

## 移植流程

① 在board里边添加相应的外设：配置时钟分频、引脚功能等

② 添加相应的config开关、Kconfig开关，用以指示相应的外设开启与关闭（本质是通过宏定义或者条件编译的方式）

③ 根据[SDK_2_14_2_FRDM-MCXA153](https://mcuxpresso.nxp.com/zh/builder?hw=FRDM-MCXA153)提供的simple_pwm示例工程编写pwm总线驱动，需要实现几个关键的函数

- mcx_pwm_init
- mcx_drv_pwm_control
- mcx_drv_pwm_enable
- mcx_drv_pwm_disable

## 驱动文件

### drv_pwm.c

pwm驱动层适配如下

```c
/*
 * Copyright (c) 2006-2024, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2024-02-26     Yilin Sun    Initial version.
 */

#include <rtthread.h>
#include <rtdevice.h>
#include "fsl_ctimer.h"

#ifdef RT_USING_PWM

typedef struct
{
    struct rt_device_pwm pwm_device;
    CTIMER_Type *ct_instance;
	uint32_t timerClock;
	const ctimer_match_t pwmPeriodChannel;
    ctimer_match_t matchChannel;
	char *name;
} mcx_pwm_obj_t;

static mcx_pwm_obj_t mcx_pwm_list[]= 
{
#ifndef BSP_USING_PWM0
    {
        .ct_instance = CTIMER1,
        .timerClock = 0,
		.pwmPeriodChannel = kCTIMER_Match_3,
		.matchChannel = kCTIMER_Match_2,
        .name = "pwm0",
    }
#endif
};
volatile uint32_t g_pwmPeriod   = 0U;
volatile uint32_t g_pulsePeriod = 0U;

static rt_err_t mcx_drv_pwm_get(mcx_pwm_obj_t *pwm, struct rt_pwm_configuration *configuration)
{
    return RT_EOK;
}

status_t CTIMER_GetPwmPeriodValue(uint32_t pwmFreqHz, uint8_t dutyCyclePercent, uint32_t timerClock_Hz)
{
    g_pwmPeriod = (timerClock_Hz / pwmFreqHz) - 1U;
    g_pulsePeriod = (g_pwmPeriod + 1U) * (100 - dutyCyclePercent) / 100;
    return kStatus_Success;
}

static rt_err_t mcx_drv_pwm_set(mcx_pwm_obj_t *pwm, struct rt_pwm_configuration *configuration)
{
    CTIMER_Type *ct = pwm->ct_instance;
	uint32_t pwmFreqHz = 1000000000 / configuration->period;
	uint8_t dutyCyclePercent = configuration->pulse * 100 / configuration->period; 
	CTIMER_GetPwmPeriodValue(pwmFreqHz, dutyCyclePercent, pwm->timerClock);
    CTIMER_SetupPwmPeriod(ct, kCTIMER_Match_3, kCTIMER_Match_2, g_pwmPeriod, g_pulsePeriod, false);
    return 0;
}

static rt_err_t mcx_drv_pwm_enable(mcx_pwm_obj_t *pwm, struct rt_pwm_configuration *configuration)
{
    CTIMER_StartTimer(pwm->ct_instance);
    return 0;
}

static rt_err_t mcx_drv_pwm_disable(mcx_pwm_obj_t *pwm, struct rt_pwm_configuration *configuration)
{
    CTIMER_StopTimer(pwm->ct_instance);
    return 0;
}

static rt_err_t mcx_drv_pwm_control(struct rt_device_pwm *device, int cmd, void *args)
{
    mcx_pwm_obj_t *pwm = device->parent.user_data;
    struct rt_pwm_configuration *configuration = (struct rt_pwm_configuration *)args;

switch (cmd)
    {
    case PWM_CMD_ENABLE:
        return mcx_drv_pwm_enable(pwm, configuration);

case PWM_CMD_DISABLE:
        return mcx_drv_pwm_disable(pwm, configuration);

case PWM_CMD_SET:
        return mcx_drv_pwm_set(pwm, configuration);

case PWM_CMD_GET:
        return mcx_drv_pwm_get(pwm, configuration);

default:
        return -RT_EINVAL;
    }

return RT_EOK;
}

static struct rt_pwm_ops mcx_pwm_ops =
{
    .control = mcx_drv_pwm_control,
};

int mcx_pwm_init(void)
{
    rt_err_t ret;
    char name_buf[8];
	
	ctimer_config_t config;
	CTIMER_GetDefaultConfig(&config);
    for (uint8_t i = 0; i < ARRAY_SIZE(mcx_pwm_list); i++)
    {
        mcx_pwm_list[i].timerClock = CLOCK_GetCTimerClkFreq(1U) / (config.prescale + 1);
		CTIMER_Init(mcx_pwm_list[i].ct_instance, &config);
        ret = rt_device_pwm_register(&mcx_pwm_list[i].pwm_device, mcx_pwm_list[i].name, &mcx_pwm_ops, &mcx_pwm_list[i]);
        if (ret != RT_EOK)
        {
            return ret;
        }
    }
    return RT_EOK;
}

INIT_DEVICE_EXPORT(mcx_pwm_init);

#endif /* RT_USING_PWM */
```

### pin_mux.c

在`BOARD_InitPins`函数里加入以下代码

```c
#ifdef BSP_USING_PWM0
	ctimer_config_t config;
	CTIMER_Init(CTIMER1, &config);
    const port_pin_config_t port1_4_pin62_config = {/* Internal pull-up/down resistor is disabled */
                                                    kPORT_PullDisable,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as CT1_MAT2 */
                                                    kPORT_MuxAlt4,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT1_4 (pin 62) is configured as CT1_MAT2 */
    PORT_SetPinConfig(PORT1, 4U, &port1_4_pin62_config);
#endif
```

### .config

加上PWM0相关开关

```
CONFIG_BSP_USING_PWM=y
CONFIG_BSP_USING_PWM0=y
```

### board/Kconfig

加入PWM0相关配置

```
menuconfig BSP_USING_PWM
        config BSP_USING_PWM
            bool "Enable PWM"
            select RT_USING_PWM
            default y

if BSP_USING_PWM
                config BSP_USING_PWM0
                    bool "Enable PWM0 output"
                    default y
            endif
```

## 测试用例

生成频率1KHz，占空比为5%的方波

```c
#include <rtthread.h>
#include <rtdevice.h>

#include <rtthread.h>
#include "board.h"
#include <rtdevice.h>

#define PWM_LED_DEV     "pwm0"
#define PWM_CHANNEL     3

int main(void)
{
    struct rt_device_pwm *pwm_dev = RT_NULL;
    rt_uint32_t period, pulse;
    period = 1000000;
    pulse = 50000;

pwm_dev = (struct rt_device_pwm *)rt_device_find(PWM_LED_DEV);
    if (pwm_dev == RT_NULL)
    {
        rt_kprintf("pwm device (%s) not found!\n", PWM_LED_DEV);
        return RT_ERROR;
    }

rt_pwm_enable(pwm_dev, PWM_CHANNEL);
	rt_pwm_set(pwm_dev, PWM_CHANNEL, period, pulse);
    while (1)
    {
    	rt_thread_mdelay(1000);
    }
    return 0;
}
```

## 实验效果

使用逻辑分析仪测量P1_4生成的波形，波形刚好频率为1KHz，占空比为5%

![方波.png](https://oss-club.rt-thread.org/uploads/20240725/eac1002825fe2d84ccf5979fb7cdee04.png.webp)