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本帖最后由 lophost 于 2023-5-17 14:57 编辑
外接25MHZ晶振
void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
HAL_StatusTypeDef ret = HAL_OK;
/* 锁住SCU(Supply configuration update) */
MODIFY_REG(PWR->CR3, PWR_CR3_SCUEN, 0);
/*
1、芯片内部的LDO稳压器输出的电压范围,可选VOS1,VOS2和VOS3,不同范围对应不同的Flash读速度,
详情看参考手册的Table 12的表格。
2、这里选择使用VOS1,电压范围1.15V - 1.26V。
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
/* 使能HSE,并选择HSE作为PLL时钟源 */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSIState = RCC_HSI_OFF;
RCC_OscInitStruct.CSIState = RCC_CSI_OFF;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 5;
RCC_OscInitStruct.PLL.PLLN = 112;
RCC_OscInitStruct.PLL.PLLP = 2;
RCC_OscInitStruct.PLL.PLLR = 2;
RCC_OscInitStruct.PLL.PLLQ = 2;
RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
if(ret != HAL_OK)
{
Error_Handler(__FILE__, __LINE__);
}
/*
选择PLL的输出作为系统时钟
配置RCC_CLOCKTYPE_SYSCLK系统时钟
配置RCC_CLOCKTYPE_HCLK 时钟,对应AHB1,AHB2,AHB3和AHB4总线
配置RCC_CLOCKTYPE_PCLK1时钟,对应APB1总线
配置RCC_CLOCKTYPE_PCLK2时钟,对应APB2总线
配置RCC_CLOCKTYPE_D1PCLK1时钟,对应APB3总线
配置RCC_CLOCKTYPE_D3PCLK1时钟,对应APB4总线
*/
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_D1PCLK1 | RCC_CLOCKTYPE_PCLK1 | \
RCC_CLOCKTYPE_PCLK2 | RCC_CLOCKTYPE_D3PCLK1);
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
/* 此函数会更新SystemCoreClock,并重新配置HAL_InitTick */
ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4);
if(ret != HAL_OK)
{
Error_Handler(__FILE__, __LINE__);
}
__HAL_RCC_CSI_ENABLE() ;
__HAL_RCC_SYSCFG_CLK_ENABLE() ;
HAL_EnableCompensationCell();
}
// /* 配置PC8为TIM8_CH3功能,输出占空比50%的方波 */
bsp_SetTIMOutPWM(GPIOC, GPIO_PIN_8, TIM8, 3, 1000000, 5000);
发现频率1MHZ是对的,占空比只有47.5%,这是为何?
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