差别

这里会显示出您选择的修订版和当前版本之间的差别。

到此差别页面的链接

--- stm32:inputcompare [2025/01/25 19:39] – laythy
+++ stm32:inputcompare [2025/01/25 20:59] (当前版本) – laythy
@@ 行 21: / 行 21: @@
 {{ :stm32:masterslavetriggermode.jpeg?nolink|}}
 {{ :stm32:pwminput.jpeg?nolink |}}
+===例程 - 测PWM频率和占空比===
+采用TIM2生成PWM信号，TIM3输入捕获，用PWMI模式测定PWM的频率和占空比。此处不列出生成PWM信号的代码，可以参考：[[stm32:pwmservo|PWM控制SG90舵机]]，生成频率1kHz，占空比千分之500的PWM信号。\\
+<code>// main.c
+#include "stm32f10x.h"                  // Device header
+#include "OLED.h"
+#include "Delay.h"
+#include "PWM.h"
+#include "InputCapture.h"
+int main(void)
+{
+    OLED_Init();
+    PWM_Init();
+    InputCapture_Init();
+    PWM_Set_PSC(72-1); // Freq = 72M / (PSC + 1) / 1000，PSC=72-1，Freq = 1KHz
+    PWM_Set_CCR1(500); // Duty = CCR / 1000
+    OLED_ShowString(1, 1, "Freq:00000Hz");
+    OLED_ShowString(2, 1, "Duty:0000/1000");
+    while(1)
+    {
+        OLED_ShowNum(1, 6, InputCapture_Get_Freq(), 5);
+        OLED_ShowNum(2, 6, InputCapture_Get_Duty(), 4);
+        Delay_ms(200);
+    }
+}
+</code>
+<code>// InputCapture.c
+#include "stm32f10x.h"                  // Device header
+void InputCapture_Init(void)
+{
+    // 时钟
+    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
+    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
+    TIM_InternalClockConfig(TIM3);
+    // GPIO - TIM3 CH1 - PA6
+    GPIO_InitTypeDef GPIO_InitStructure;
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
+    GPIO_Init(GPIOA, &GPIO_InitStructure);
+    // 时基单元
+    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStrucure;
+    TIM_TimeBaseInitStrucure.TIM_ClockDivision = TIM_CKD_DIV1;
+    TIM_TimeBaseInitStrucure.TIM_CounterMode = TIM_CounterMode_Up;
+    TIM_TimeBaseInitStrucure.TIM_Period = 65535; // ARR
+    TIM_TimeBaseInitStrucure.TIM_Prescaler = 72 - 1; // PSC 决定测周法的标准频率f。PSC=72-1, f=1M
+    // 关于测频率上下限和修改，看江科大视频34:00处
+    TIM_TimeBaseInitStrucure.TIM_RepetitionCounter = 0;
+    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStrucure);
+    // 输入捕获单元
+    TIM_ICInitTypeDef TIM_ICInitStructure;
+    TIM_ICStructInit(&TIM_ICInitStructure);
+    TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
+    TIM_ICInitStructure.TIM_ICFilter = 0xF;
+    TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
+    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
+    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
+    TIM_PWMIConfig(TIM3, &TIM_ICInitStructure); // PWMI模式，江科大视频28:49处
+    // 主从触发模式 - 触发源和从模式
+    TIM_SelectInputTrigger(TIM3, TIM_TS_TI1FP1);
+    TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);
+    // 启动定时器
+    TIM_Cmd(TIM3, ENABLE);
+}
+uint32_t InputCapture_Get_Freq(void) // 读取频率，单位赫兹
+{
+    uint32_t n = TIM_GetCapture1(TIM3);
+    return 1000000 / n;
+}
+uint16_t InputCapture_Get_Duty(void) // 读取占空比，0-1000，单位千分之
+{
+    return TIM_GetCapture2(TIM3) * 1000 / TIM_GetCapture1(TIM3);
+}
+</code>