TI C2000: Control – enhanced Pulse Width Modulation (ePWM)

TI C2000 Real-Time Microcontroller: Control, Sensing, and Communication

ePWM Module Signals and Connections
ePWM Block Diagram
ePWM Time-Base Sub-Module
ePWM Compare Sub-Module
ePWM Action Qualifier Sub-Module
ePWM Dead-Band Sub-Module
ePWM Chopper Sub-Module
ePWM Trip-Zone and Digital Compare Sub-Module
ePWM Event-Trigger Sub-Module
Hi-Resolution PWM (HRPWM)
Example: ePWM1A

ePWM Module Signals and Connections

ePWM Block Diagram

ePWM Time-Base Sub-Module

ePWM Compare Sub-Module

ePWM Action Qualifier Sub-Module

ePWM Dead-Band Sub-Module

ePWM Chopper Sub-Module Purpose of the PWM Chopper

Allows a high frequency carrier signal to modulate the PWM waveform generated by the Action Qualifier and Dead-Band modules
Used with pulse transformer-based gate drivers to control power switching elements

ePWM Trip-Zone and Digital Compare Sub-Module

Purpose of the Digital Compare Sub-Module

Generates compare events that can:
- Trip the ePWM
- Generate a Trip interrupt
- Sync the ePWM
- Generate an ADC start of conversion
Digital compare module inputs are:
- Input X-Bar
- ePWM X-Bar
- Trip-zone input pins
A compare event is generated when one or more of its selected inputs are either high or low
Optional Blanking can be used to temporarily disable the compare action in alignment with PWM switching to eliminate noise effects

ePWM Event-Trigger Sub-Module

Hi-Resolution PWM (HRPWM)

Example: ePWM1A

void init_EPWM1A_GPIO(void)
{
    EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 1;  // Disable pull-up on GPIO0 (EPWM1A)
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1; // Configure GPIO0 as EPWM1A
    EDIS;
}

// Configures ePWM1A to generate a 20 kHz PWM carrier signal
void init_EPWM1A(void)
{
    // Set epwm1 to upcount mode, 0x0
    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
    
    // Free Run, do not stop      
    EPwm1Regs.TBCTL.bit.FREE_SOFT = 0x2;
    
    // Disable phase loading, 0x0            
    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;         

    // Set epwm1 counter 20KHz, set timer period
    // 50MHz / 20KHz = 2500
    EPwm1Regs.TBPRD = 2500;                         
    EPwm1Regs.TBPHS.bit.TBPHS = 0x0000; // Phase is 0
    EPwm1Regs.TBCTR = 0x0000;           // Clear counter

    // For EPWM1A
    EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR; // Clear when counter = compareA
    EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET;   // Set when timer is 0
}

// 0: 0% duty cycle, 2500: 100% duty cycle
EPwm1Regs.CMPA.bit.CMPA = (Uint16)pwmVal;

void init_EPWM1A_GPIO(void)
{
    EALLOW;
    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 1;  // Disable pull-up on GPIO0 (EPWM1A)
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1; // Configure GPIO0 as EPWM1A
    EDIS;
}

// Configures ePWM1A to generate a 20 kHz PWM carrier signal
void init_EPWM1A(void)
{
    // Set epwm1 to upcount mode, 0x0
    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
    
    // Free Run, do not stop      
    EPwm1Regs.TBCTL.bit.FREE_SOFT = 0x2;
    
    // Disable phase loading, 0x0            
    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;         

    // Set epwm1 counter 20KHz, set timer period
    // 50MHz / 20KHz = 2500
    EPwm1Regs.TBPRD = 2500;                         
    EPwm1Regs.TBPHS.bit.TBPHS = 0x0000; // Phase is 0
    EPwm1Regs.TBCTR = 0x0000;           // Clear counter

    // For EPWM1A
    EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR; // Clear when counter = compareA
    EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET;   // Set when timer is 0
}

// 0: 0% duty cycle, 2500: 100% duty cycle
EPwm1Regs.CMPA.bit.CMPA = (Uint16)pwmVal;

Reference

[1] TMS320F2837xD Microcontroller Workshop