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28035 如何提高PWM分辨率

JINYONG LI1
Prodigy 90 points
Other Parts Discussed in Thread: CONTROLSUITE

28035芯片，总共要用到8个PWM端口输出，当PWM频率设置为20KHz时，TBPRD设置为1500，那么实际可调占空比的数值范围为0-1500，如何在频率不变的情况下，提高占空比数值范围？

下面是PWM设定程序

void InitEPWM_AQ_DB(void)
{
char i;
volatile struct EPWM_REGS *PWMDef[] = {&EPwm1Regs,&EPwm2Regs,&EPwm3Regs,&EPwm4Regs};

InitEPwm1Gpio(); //PWM1AB 引脚配置
InitEPwm2Gpio(); //PWM2AB 引脚配置
InitEPwm3Gpio(); //PWM3AB 引脚配置
InitEPwm4Gpio(); //PWM4AB 引脚配置

for(i=0;i<4;i++)
{
EALLOW;

//T_PWM =2 x TBPRD x T_TBCLK
PWMDef[i]->TBPRD = 1500; //频率20KHz
//EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
PWMDef[i]->CMPA.half.CMPA = 0; //占空比
PWMDef[i]->CMPB = 0; //PWMxB占空比
PWMDef[i]->TBPHS.half.TBPHS = 0x0000; // Phase is 0
PWMDef[i]->TBCTR = 0x0000; // Clear counter

// Setup TBCLK
PWMDef[i]->TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Count up down，中间对其计数模式
PWMDef[i]->TBCTL.bit.PHSEN = TB_DISABLE; // Disable phase loading
PWMDef[i]->TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
PWMDef[i]->TBCTL.bit.HSPCLKDIV = TB_DIV1; // Clock ratio to SYSCLKOUT;
PWMDef[i]->TBCTL.bit.CLKDIV = TB_DIV1;

PWMDef[i]->AQCTLA.bit.CAU = AQ_SET;
PWMDef[i]->AQCTLA.bit.CAD = AQ_CLEAR;
PWMDef[i]->AQCTLB.bit.CBU = AQ_SET ;
PWMDef[i]->AQCTLB.bit.CBD = AQ_CLEAR;

PWMDef[i]->DBCTL.bit.OUT_MODE = DB_DISABLE; //S1 = 0; S0 = 0 关闭死区控制

EDIS;
}
}

  • 0
    TI__Guru 60308 points

    28035芯片，总共要用到8个PWM端口输出，当PWM��率设置为20KHz时，TBPRD设置为1500，那么实际可调占空比的数值范围为0-1500，如何在频率不变的情况下，提高占空比数值范围？

    Eric:

    使用高精度PWM。

    C:\ti\controlSUITE\device_support\f2803x\v130\DSP2803x_examples_ccsv5\hrpwm

    C:\ti\controlSUITE\device_support\f2803x\v130\DSP2803x_examples_ccsv5\hrpwm_duty_sfo_v6

  • 0 回复 Eric Ma
    Prodigy 90 points

    谢谢你回复， 请问8个通道都可以设置为高分辨率吗？  我安装的是CCS6.1没有找到例子文件夹，能否发个程序样例看看

  • 0 回复 JINYONG LI1
    Prodigy 90 points

    已经学会使用，非常感谢

  • 0 回复 JINYONG LI1
    Guru 56631 points

    分享一下吧   这个硬件是有限制的     有个最高分辨率

  • 0 回复 mangui zhang
    Prodigy 90 points

    按照例程的做法，分辨率只能比原来提高1倍，不知道有没有更好的方法实现更高的分辨率

    // Some useful Period vs Frequency values
    // SYSCLKOUT = 60 MHz
    // ---------------------------
    // Period Frequency
    // 1000 60 kHz
    // 800 75 kHz
    // 600 100 kHz
    // 500 120 kHz
    // 250 240 kHz
    // 200 300 kHz
    // 100 600 kHz
    // 50 1.2 Mhz
    // 25 2.4 Mhz
    // 20 3.0 Mhz
    // 12 5.0 MHz
    // 10 6.0 MHz
    // 9 6.7 MHz
    // 8 7.5 MHz
    // 7 8.6 MHz
    // 6 10.0 MHz
    // 5 12.0 MHz


    void HRPWM1_Config(Uint16 period)
    {
    // ePWM1 register configuration with HRPWM
    // ePWM1A toggle low/high with MEP control on Rising edge

    EPwm1Regs.TBCTL.bit.PRDLD = TB_IMMEDIATE; // set Immediate load
    EPwm1Regs.TBPRD = period-1; // PWM frequency = 1 / period
    EPwm1Regs.CMPA.half.CMPA = period / 2; // set duty 50% initially
    EPwm1Regs.CMPA.half.CMPAHR = (1 << 8); // initialize HRPWM extension
    EPwm1Regs.CMPB = period / 2; // set duty 50% initially
    EPwm1Regs.TBPHS.all = 0;
    EPwm1Regs.TBCTR = 0;

    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // EPwm1 is the Master
    EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
    EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
    EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;

    EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
    EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
    EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
    EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

    EPwm1Regs.AQCTLA.bit.ZRO = AQ_CLEAR; // PWM toggle low/high
    EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
    EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
    EPwm1Regs.AQCTLB.bit.CBU = AQ_SET;

    EALLOW;
    EPwm1Regs.HRCNFG.all = 0x0;
    EPwm1Regs.HRCNFG.bit.EDGMODE = HR_REP; //MEP control on Rising edge
    EPwm1Regs.HRCNFG.bit.CTLMODE = HR_CMP;
    EPwm1Regs.HRCNFG.bit.HRLOAD = HR_CTR_ZERO;
    EDIS;
    }