1.基本介绍

A4950的峰值输出电流可达±3.5 A，工作电压为7.6~40v。

优点：相对于L298N模块控制2个电机正反转仅需要4个I/O口，体积小，发热低。

缺点：需要2个PWM引脚才能控制正反转，所以控制2个电机需要4PWM引脚，会使用STM32F103芯片一个定时器的全部PWM通道。

A4950模块是靠输入2路的PWM占空比的差值，来设定输出电压的大小，当差值为0时输出为0，反之当占空比差值为100时输出最大。

2.引脚功能和接线

3程序设计

接下来我使用STM32F103C8T6的标准库代码为例

定时器3初始化代码

#include "stm32f10x.h"                  // Device header

void PWM_Init3(void)
{
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);

	GPIO_InitTypeDef GPIO_InitStructure1;
	GPIO_InitStructure1.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStructure1.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
	GPIO_InitStructure1.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB,&GPIO_InitStructure1);

	GPIO_InitTypeDef GPIO_InitStructure2;
	GPIO_InitStructure2.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStructure2.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;
	GPIO_InitStructure2.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA,&GPIO_InitStructure2);

	TIM_InternalClockConfig(TIM3);
	
	
	TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
	TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
	TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
	
	TIM_TimeBaseInitStructure.TIM_Period  = 100-1;  //ARR
	TIM_TimeBaseInitStructure.TIM_Prescaler  = 3600-1; //PSC
	TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
	TIM_TimeBaseInit(TIM3,&TIM_TimeBaseInitStructure);
	
	TIM_OCInitTypeDef TIM_OCInitStructure;
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;  //输出比较模式
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
	TIM_OCInitStructure.TIM_Pulse = 0;//CCR
	
    TIM_OC1Init(TIM3,&TIM_OCInitStructure);
	TIM_OC2Init(TIM3,&TIM_OCInitStructure);
	TIM_OC4Init(TIM3,&TIM_OCInitStructure);
    TIM_OC3Init(TIM3,&TIM_OCInitStructure);

	TIM_ClearFlag(TIM3, TIM_FLAG_Update);
	TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE);
	
	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
	
	NVIC_InitTypeDef NVIC_InitStructure;
	NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
	NVIC_Init(&NVIC_InitStructure);
	
	TIM_Cmd(TIM3,ENABLE);
 }

 
 
void PWM_SetCompare1(uint16_t Compare)
 {
	 TIM_SetCompare1 (TIM3,Compare);
 }
  
void PWM_SetCompare2(uint16_t Compare)
 {
	 TIM_SetCompare2 (TIM3,Compare);
 }
 
void PWM_SetCompare3(uint16_t Compare)
 {
	 TIM_SetCompare3 (TIM3,Compare);
 }

void PWM_SetCompare4(uint16_t Compare)
 {
	 TIM_SetCompare4 (TIM3,Compare);
 }

电机控制函数

#include "stm32f10x.h"                  // Device header
#include "PWN.h"
void Motor_Init(void)
{
	PWM_Init3();
}
// you
void Motor_SetSpeed2(int16_t Speed)
{
	
		PWM_SetCompare3(50-Speed/2);
		PWM_SetCompare1(50+Speed/2);

	
}
//zuo
void Motor_SetSpeed1(int16_t Speed)
{
	
		PWM_SetCompare2(50-Speed/2);
		PWM_SetCompare4(50+Speed/2);

}

 mian函数代码

#include "stm32f10x.h"                  // Device header
#include "Motor.h"
int main (void)
{
	Motor_Init(); //电机驱动初始化
	while(1)
	{
		
		Motor_SetSpeed1(20);//给电机1 向前20速度
		Motor_SetSpeed2(20);//给电机2 向前20速度
		
	}

}

全部源码链接:主控/C8T6/A4950 · 亟待/electronic-game-code - 码云 - 开源中国 (gitee.com)https://gitee.com/AD123zsg/electronic-game-code/tree/master/%E4%B8%BB%E6%8E%A7/C8T6/A4950