Question

我可能只是在这些寄存器中找到了一个看不见的树林时刻，但是我无法让PWM工作在dsPIC33FJ32MC102微控制器上（警告：大PDF）我正在玩。我已经按照数据表和进一步的application note（警告：另一个PDF）甚至代码样本，我看不出我做错了什么，虽然在我的测试平台上我得到Vcc的高输出和低输出接地。我已将故障引脚连接到Vcc并禁用了寄存器密钥代码，因此我的更改应该会看到一些效果。我究竟做错了什么？

#define FOSC    (3686400ULL)
#define FCY     (FOSC/2)

#include <xc.h>
#include <libpic30.h>

...

#pragma config PWMPIN = ON              // Motor Control PWM Module Pin Mode bit (PWM module pins controlled by PORT register at device Reset)
#pragma config PWMLOCK = OFF             

...

void main(void){

...

//setup PWM

//Clear faults
IFS3bits.PWM1IF     = 0;
IFS3bits.FLTA1IF    = 0;
IFS4bits.FLTB1IF    = 0;

//Setup dead times
P1DTCON1bits.DTAPS  = 0b00; //Dead time tick is 1 TCY
P1DTCON1bits.DTBPS  = 0b00;
P1DTCON1bits.DTA    = 10;    //Dead time is 10TCY ~= 3uS
P1DTCON1bits.DTB    = 10;
P1DTCON2bits.DTS1A  = 0;    //Active and Inactive transition dead times
P1DTCON2bits.DTS2A  = 0;    //0 takes A dead time
P1DTCON2bits.DTS3A  = 0;    //1 takes B dead time
P1DTCON2bits.DTS1I  = 1;
P1DTCON2bits.DTS2I  = 1;
P1DTCON2bits.DTS3I  = 1;

P1TCONbits.PTOPS    = 0b0000; //1 CPU tick = 1 PWM tick
P1TCONbits.PTCKPS   = 0b00;
P1TCONbits.PTMOD    = 0b00;
P1TCONbits.PTSIDL   = 0;      //Run when CPU idles

// no longer necessary since I disabled register write lock:
//    __builtin_write_PWMSFR(&P1FLTACON,0x0000,&PWM1KEY);
//    __builtin_write_PWMSFR(&P1FLTBCON,0x0000,&PWM1KEY);
//    __builtin_write_PWMSFR(&PWM1CON1 ,0x0077,&PWM1KEY);

PWM1CON1 = 0x0077;    //Enable all 3 channels
P1FLTACON = 0x0000;   //Disable faults
P1FLTBCON = 0x0000;

//Setup Wave freq/duty
//Fosc = 7.3728 MHz -> Fcy = 3.6864MHz
//Desire a PWM of 20250Hz (smaller scalar error than 20kHz)
//P1TPER = [Fcy/(Fpwm*Scalar)] - 1
//Therefore P1TPER = [3.6864M/(20250*1)] - 1 = 181;
P1TPER              = 181;
P1DC1               = 0x7FFF;   // 0x7FFF for 50%
P1DC2               = 0x7FFF;
P1DC3               = 0x7FFF;

P1OVDCON            = 0x3F00;   //Disable override; override disables PWM
PWM1CON2            = 0x0000;    
P1TCONbits.PTEN     = 1;        //Turn on

...

while(1);
}

Answer 1

我相信您已将计时器设置为从0到181（P1TPER）计数，然后重置并重复。但是你已经将占空比寄存器设置为0x7FFF，这大于181.所以我认为占空比值永远不会小于定时器值，因此输出永远不会改变。尝试将占空比寄存器设置为181/2 = 90，以获得50％的占空比。

无法在dsPIC33F上初始化PWM

1 个答案: