如何使伺服马达启动然后停止

Question

我想让马达运行1s，然后停下来。它被用来推送物品。这将在一个for循环中用来确定马达推送的项目数。我使用的电机是FS90R，芯片是pic18f4550。电机需要1.5毫秒的脉冲才能停止，并需要1毫秒的脉冲才能前进。

/* TimerPWM.c Program to generate PWM at RC2
 *  Use Timer2
 *  Frequency of OSC = 48 MHz, Prescaler = 16
 *  PR2 register set the frequency of waveform
 *  CCPR1L with CP1CONbits.DC1B0, CCP1CONbits.DC1B1 set the On-Time 
 *  Use Timer0 for the one second delay function
 */
#include <xc.h>
#include "delays.h"

void Delay1sec(void); //Function to provide 1 sec delay using Timer0

void Delay1sec(void) {
    TMR0H = 0X48; //Starting count value
    TMR0L = 0XE5;

    INTCONbits.TMR0IF = 0; //Clear flag first
    T0CONbits.TMR0ON = 1; //Turn on Timer 0

    while (INTCONbits.TMR0IF == 0); //Wait for time is up when TMR0IF=1 
    T0CONbits.TMR0ON = 0; //Turn off Timer 0 to stop counting
}

void motorgo(){
    TRISC = 0x00; //PortC RC2 connects to motor
    TRISD = 0x00; //PortD connected to 8 LEDs
    T0CON = 0b00000111; //Off Timer0, 16-bits mode, prescaler to 256

    T2CON = 0b00000111; //Timer2 is On, Prescaler is 16

    CCP1CON = 0b00001100; //Turn on PWM on CCP1, output at RC2
    
    PR2 = 149;
    CCPR1L = 37;
    
}

void motorstop(){
    TRISC = 0x00; //PortC RC2 connects to motor
    TRISD = 0x00; //PortD connected to 8 LEDs
    T0CON = 0b00000111; //Off Timer0, 16-bits mode, prescaler to 256

    T2CON = 0b00000111; //Timer2 is On, Prescaler is 16

    CCP1CON = 0b00001100; //Turn on PWM on CCP1, output at RC2
    
    PR2 = 1124;
    CCPR1L =1124;
    
}

void main(void) {
    ADCON1 = 0x0F;
    CMCON = 0x07;
    TRISC = 0x00; //PortC RC2 connects to motor
    TRISD = 0x00; //PortD connected to 8 LEDs
    T0CON = 0b00000111; //Off Timer0, 16-bits mode, prescaler to 256

    T2CON = 0b00000111; //Timer2 is On, Prescaler is 16

    CCP1CON = 0b00001100; //Turn on PWM on CCP1, output at RC2
     //Load period of PWM 0.2msec for 5KHz

    while (1) //Repeatedly
    {   
        motorgo();
        Delay1sec();
        //Delay1sec();
 
        motorstop();

    }
}

Answer 1

LucK发布的代码看起来不太可能工作。

在我看来，我认为海报不理解PIC18F4550控制器中脉宽调制的局限性。

下面是一个完整的应用程序，它应该让FeeTech FS90R伺服运行1秒，停止9秒，然后重复：

/*
 * File:     main.c
 * Author:   dan1138
 * Target:   PIC18F4550
 * Compiler: XC8 v1.45
 * IDE:      MPLAB v8.92
 *
 * Description:
 * 
 * See: https://stackoverflow.com/questions/73161548/how-to-make-servo-moto-to-start-then-stop
 *
 *                               PIC18F4550
 *                       +----------:_:----------+
 *             VPP ->  1 : MCLR/VPP      PGD/RB7 : 40 <> PGD
 *                 <>  2 : RA0/AN0       PGC/RB6 : 39 <> PGC
 *                 <>  3 : RA1/AN1       PGM/RB5 : 38 <> 
 *                 <>  4 : RA2/AN2      AN11/RB4 : 37 <> 
 *                 <>  5 : RA3/AN3       AN9/RB3 : 36 <> 
 *                 <>  6 : RA4           AN8/RB2 : 35 <> 
 *                 <>  7 : RA5/AN4       SCL/RB1 : 34 <> 
 *                 <>  8 : RE0/AN5       SDA/RB0 : 33 <> 
 *                 <>  9 : RE1/AN6           VDD : 32 <- PWR
 *                 <> 10 : RE2/AN7           VSS : 31 <- GND
 *             PWR -> 11 : VDD               RD7 : 30 <> 
 *             GND -> 12 : VSS               RD6 : 29 <> 
 *           20MHZ -> 13 : OSC1              RD5 : 28 <> 
 *           20MHZ <- 14 : OSC2              RD4 : 27 <> 
 *                 <> 15 : RC0         RX/DT/RC7 : 26 <> 
 *                 <> 16 : RC1/CCP2    TX/CK/RC6 : 25 <> 
 *          SERVO1 <> 17 : RC2/CCP1       D+/RC5 : 24 <-
 *             3v3 <> 18 : VUSB           D-/RC4 : 23 <-
 *                 <> 19 : RD0               RD3 : 22 <> 
 *                 <> 20 : RD1               RD2 : 21 <> 
 *                       +-----------------------:
 *                                DIP-40
 *  
 *
 * Created on July 30, 2022, 8:42 PM
 */
#pragma config PLLDIV = 5           /* PLL Prescaler Selection bits (Divide by 5 (20 MHz oscillator input)) */
#pragma config CPUDIV = OSC1_PLL2   /* System Clock Postscaler Selection bits ([Primary Oscillator Src: /1][96 MHz PLL Src: /2]) */
#pragma config USBDIV = 2           /* USB Clock Selection bit (used in Full-Speed USB mode only; UCFG:FSEN = 1) (USB clock source comes from the 96 MHz PLL divided by 2) */
#pragma config FOSC = INTOSC_HS     /* Oscillator Selection bits (Internal oscillator, HS oscillator used by USB (INTHS)) */
#pragma config FCMEN = OFF          /* Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled) */
#pragma config IESO = OFF           /* Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled) */
#pragma config PWRT = OFF           /* Power-up Timer Enable bit (PWRT disabled) */
#pragma config BOR = OFF            /* Brown-out Reset Enable bits (Brown-out Reset disabled in hardware and software) */
#pragma config BORV = 3             /* Brown-out Reset Voltage bits (Minimum setting 2.05V) */
#pragma config VREGEN = ON          /* USB Voltage Regulator Enable bit (USB voltage regulator enabled) */
#pragma config WDT = OFF            /* Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit)) */
#pragma config WDTPS = 32768        /* Watchdog Timer Postscale Select bits (1:32768) */
#pragma config CCP2MX = ON          /* CCP2 MUX bit (CCP2 input/output is multiplexed with RC1) */
#pragma config PBADEN = OFF         /* PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset) */
#pragma config LPT1OSC = OFF        /* Low-Power Timer 1 Oscillator Enable bit (Timer1 configured for higher power operation) */
#pragma config MCLRE = ON           /* MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled) */
#pragma config STVREN = ON          /* Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset) */
#pragma config LVP = OFF            /* Single-Supply ICSP Enable bit (Single-Supply ICSP disabled) */
#pragma config ICPRT = OFF          /* Dedicated In-Circuit Debug/Programming Port (ICPORT) Enable bit (ICPORT disabled) */
#pragma config XINST = OFF          /* Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode)) */
#pragma config CP0 = OFF            /* Code Protection bit (Block 0 (000800-001FFFh) is not code-protected) */
#pragma config CP1 = OFF            /* Code Protection bit (Block 1 (002000-003FFFh) is not code-protected) */
#pragma config CP2 = OFF            /* Code Protection bit (Block 2 (004000-005FFFh) is not code-protected) */
#pragma config CPB = OFF            /* Boot Block Code Protection bit (Boot block (000000-0007FFh) is not code-protected) */
#pragma config CPD = OFF            /* Data EEPROM Code Protection bit (Data EEPROM is not code-protected) */
#pragma config WRT0 = OFF           /* Write Protection bit (Block 0 (000800-001FFFh) is not write-protected) */
#pragma config WRT1 = OFF           /* Write Protection bit (Block 1 (002000-003FFFh) is not write-protected) */
#pragma config WRT2 = OFF           /* Write Protection bit (Block 2 (004000-005FFFh) is not write-protected) */
#pragma config WRTC = OFF           /* Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) are not write-protected) */
#pragma config WRTB = OFF           /* Boot Block Write Protection bit (Boot block (000000-0007FFh) is not write-protected) */
#pragma config WRTD = OFF           /* Data EEPROM Write Protection bit (Data EEPROM is not write-protected) */
#pragma config EBTR0 = OFF          /* Table Read Protection bit (Block 0 (000800-001FFFh) is not protected from table reads executed in other blocks) */
#pragma config EBTR1 = OFF          /* Table Read Protection bit (Block 1 (002000-003FFFh) is not protected from table reads executed in other blocks) */
#pragma config EBTR2 = OFF          /* Table Read Protection bit (Block 2 (004000-005FFFh) is not protected from table reads executed in other blocks) */
#pragma config EBTRB = OFF          /* Boot Block Table Read Protection bit (Boot block (000000-0007FFh) is not protected from table reads executed in other blocks) */

/*   Specify the System clock frequency in Hz */
#define FSYS (8000000UL)
    
/*   Specify the Peripheral clock frequency in Hz */
#define FCY  (FSYS/4UL)

#define _XTAL_FREQ FSYS

#include <xc.h>

void PIC_Init(void) {
    INTCON = 0;     /* disable interrupts */
    INTCON2 = 0xF5;
    INTCON3 = 0xC0;
    PIE1 = 0;
    PIE2 = 0;

    OSCCON = 0x70;      /* set internal oscillator to 8 MHz */

    RCONbits.IPEN = 0;  /* use legacy interrupt model */

    ADCON1 = 0x0F;      /* Disable ADC inputs  */

    CMCON  = 0x07;      /* disable Comparators */

    LATA   = 0x00;
    TRISA  = 0xC0;      /*  */
    LATB   = 0x00;
    TRISB  = 0x00;      /*  */
    LATC   = 0x00;
    TRISC  = 0x60;      /*  */
    LATD   = 0x00;
    TRISD  = 0x00;
    LATE   = 0x00;
    TRISE &= ~0x03;     /*  */
}

/* global variable to hold pulse width for servo */
volatile unsigned short ServoPulse;
volatile unsigned char  ServoRefreshCount;
volatile unsigned char  OneSecondTimeoutRunning;

/* High priority interrupt handled here */
void __interrupt(high_priority) ISR_High (void)
{
    if (PIE1bits.TMR2IE)   // test if TMR2 interrupt is enabled
    { 
        if (PIR1bits.TMR2IF) // test if TMR2 interrupt is asserted
        {
            PIR1bits.TMR2IF = 0;  // reset T2 assertion
            if(ServoRefreshCount)
            {
                ServoRefreshCount--;
                CCP1CON = 0b00001100;   // PWM mode
                CCPR1L  = 0;
            }
            else
            {
                ServoRefreshCount = 9;
                CCPR1L = (unsigned char)(ServoPulse >> 2);
                if(ServoPulse & 2) CCP1CONbits.DC1B1 = 1;
                if(ServoPulse & 1) CCP1CONbits.DC1B0 = 1;
                if (OneSecondTimeoutRunning) OneSecondTimeoutRunning--;
            }
        }
    }
} 

/* Low priority interrupt handled here */
void __interrupt(low_priority) ISR_Low (void)
{
}    
// initialize the PWM and interrupt on T2 overflow
void Init_PWM( void )
{ 
    PIE1bits.TMR2IE = 0;    // turn off TMR2 interrupt
    TRISC &= (0b11111011);  // make RC2 output for PWM
    
    T2CON = 0b00000010;     // postscaler 1:1
                            // TMR2 off
                            // prescaler 1:16
    
    PR2 = 250-1;            // set PWM period
    TMR2 = 0;
    
    CCP1CON = 0b00001100;   // PWM mode
    CCPR1L  = 0;
    ServoPulse = 0;
    ServoRefreshCount = 0;
    IPR1bits.TMR2IP  = 1;   // use high priority interrupt handler
    T2CONbits.TMR2ON = 1;   // turn on TMR2
    PIE1bits.TMR2IE  = 1;   // turn on TMR2 interrupt
}
/* Set PWM to stop motor */
void MotorStop (void)
{
    PIE1bits.TMR2IE  = 0;
    ServoPulse = 750;       // Set PWM for 1500 microsecond pulse
    PIE1bits.TMR2IE  = 1;
}
/* Set PWM to run motor clockwise */
void MotorRunCW (void)
{
    PIE1bits.TMR2IE  = 0;
    ServoPulse = 500;       // Set PWM for 1000 microsecond pulse
    PIE1bits.TMR2IE  = 1;
}
/* Set PWM to run motor counterclockwise */
void MotorRunCCW (void)
{
    PIE1bits.TMR2IE  = 0;
    ServoPulse = 1000;       // Set PWM for 2000 microsecond pulse
    PIE1bits.TMR2IE  = 1;
}
/* Start one second timeout */
void StartOneSecondTimeout(void)
{
    OneSecondTimeoutRunning = 50;
}
/* Check if timeout is running */
unsigned char OneSecondTimeoutIsRunning(void)
{
    if(OneSecondTimeoutRunning) return 1;
    return 0;
}
/*
 * Main application
 */
void main(void) 
{
    unsigned char DemoState;

    /* Initialize application*/
    PIC_Init();
    Init_PWM();
    
    GIEL = 1;   /* enable low priority interrupts */
    GIEH = 1;   /* enable global interrupts */

    /*
     * Demo application.
     * 
     * After Power-On-Reset start motor for one second.
     * 
     * Repeat sequence every 10 seconds.
     * 
     */
    MotorStop();
    DemoState = 0;
    /* Process loop for application */
    for(;;)
    {
        if(!OneSecondTimeoutIsRunning())
        {
            StartOneSecondTimeout();
            DemoState++;
            if(DemoState ==  1) 
                MotorRunCW();

            if(DemoState ==  2) 
                MotorStop();

            if(DemoState == 10) {
                DemoState = 0;
                Nop();
            }
        }
    }
}