如何正确配置PWM与输出比较模块和定时器

您好，我正在与PIC24FJ128DA210一起工作，我有一些关于如何正确配置PWM与输出比较模块和定时器2的问题。特殊信息：FoSC＝8MHz的PLL模式启用（它可能是32 MHz）PWM目标频率＝88HZI在数据表中看到：- OCxR是寄存器THAT控制占空比——OCxRS是控制周期的寄存器，但是配置time2和选择时钟源似乎是PWM的一个整体周期。所以，我的问题是：每个寄存器都要设置哪一个值才能正常工作？我从PIC24F系列参考得到的计算结果是：PWM周期＝[（PRY）+1 ] *Test*（TMRY PrimCale值），从这里我首先在PRIM2配置上设置PR2目标值，我设定PWM周期（我的目标频率）为48 8Hz。在OC1R寄存器上设置最大周期？然后，我有：PWM频率＝1 / [ PWM周期]，我不知道在哪里使用它…最后我们的PWM占空比是用最大PWM分辨率（比特）＝（Log10（fCy/（fPWM＊（定时器预缩放值））/Log10^ 2）计算的），它给了我最大的比特＝15000。正确的PWM模块？这让我很困惑，我真的想知道它是如何工作的。这是我的代码，你会注意到我需要修复OC1R和OC1RS的值。谢谢你的时间，我希望有一个答复来澄清我所拥有的这个问题。



      以下为原文

    Hello, I'm working with the PIC24FJ128DA210 and I have some questions about how to configure properly the PWM with the Output Compare module and Timer 2.

Special info:
Fosc = 8MHz with PLL mode enabled (It might be 32MHz)
PWM Target frequency = 488Hz

I saw in the datasheet that:
- OCxR is the register that controls the duty cycle
- OCxRS is the register that controls the period

However, it seems that configuring Timer2 and selecting as clock source is used as an overall Period for the PWM.

So, my question is: Which value do I have to set to each register to work properly?

I get the calculations from the PIC24F Family Reference an states that:

PWM Period = [(PRy) + 1] * TCY * (TMRy Prescale Value)

From here I have first the PR2 Target value to be set on the Timer2 configuration, I set a PWM Period (my target frequency) as 488Hz.

Is the PR2 the maximum value that I have to set the Maximum period on the OC1R Register?

Then, I have:
PWM Frequency = 1/[PWM Period]

Which I don't know where to use it...

Finally we have the PWM Duty Cycle which is calculated with:
Max PWM Resolution (bits) = (log10(FCY/(Fpwm * (timer Prescale Value)))/log10 ^2)
Which gave me the maximum bits = 15.00083

Where do I put each value to configure properly the PWM module? This is confusing me a lot, and I really want to learn how it works.

Here is my code and you will note that I need to fix the OC1R and OC1RS values selected.

Thanks for your time and I hope for a reply to clear this issue that I have.

    // PWM LEVEL Output
    // 100% approx = 32786.9 or 15.00083 bits

    // LEVEL_1 is 20 % PWM Output
#define LEVEL_1 6557
   
    // LEVEL_2 is 50 % PWM Output
#define LEVEL_2 16394
   
    // LEVEL_3 is 80 % PWM Output
#define LEVEL_3 26230
   
    // LEVEL_4 is 95 % PWM Output
#define LEVEL_4 31147

void Timer2_ForPWM()
{
    // Set Timerx and Timery act as two 16bit timers
    T2CONbits.T32 = 0;
   
    // Set Clock Prescale 1:1
    T2CONbits.TCKPS = 0b00;
   
    // Internal clock is selected (FOSC/2)
    T2CONbits.TCS = 0;
   
    // Gated time accumulation disabled
    T2CONbits.TGATE = 0;
   
    // PR2 = (2.05mS/62.5nS) - 1 = 32799 = 0x801F
    // Period = 2.05mS = 488Hz
    // Tcy = 62.5nS
    PR2 = 0x801F;
   
    // Initialize TMR2 count is 0
    TMR2 = 0;
   
    // Start the 16bit Timerx
    T2CONbits.TON = 1;
}

void PWM_Init()
{
    // Unlocking PPS
    __builtin_write_OSCCONL(OSCCON & 0xbf);
   
    // RD8->OC1:OC1;
    RPOR1bits.RP2R = 0x0012;
   
    // Locking PPS
    __builtin_write_OSCCONL(OSCCON | 0x40);
   
    // Duty cycle = OC1RS / (PR2+1) = 50 %
    OC1RS = LEVEL_3;
   
    OC1R = LEVEL_3;
   
    // Select the current OC1 as the synchronization source
    OC1CON2bits.SYNCSEL = 0b11111;
   
    // Synchronize OC1 with the source designated by the SYNCSEL bits
    OC1CON2bits.OCTRIG = 0;
   
    // OC1 Timer2 Selected as clock source
    OC1CON1bits.OCTSEL = 0b000;
   
    // Edge-Aligned PWM mode on OC1
    OC1CON1bits.OCM = 0b110;
   
    // The Fault input enable bits are disabled
    OC1CON1bits.ENFLT = 0b000;
   
    // The Fault status bits are disabled
    OC1CON1bits.OCFLT = 0b000;
}