Other Parts Discussed in Thread: C2000WARE, TMS320F28379D
I cannot get high-res output on ePWM1 when using shadow mode set to load on CTR=PRD. I’ve taken the hrpwm_ex1_duty_sfo C2000ware HRPWM example and modified to demonstrate this (code pasted below).
I can see that with the HRPWM shadow load event set to HRPWM_LOAD_ON_CNTR_ZERO there is a fine resolution on the PWM duty cycle output. However, with HRPWM_LOAD_ON_CNTR_PERIOD there is not. Is this a known restriction?
//#############################################################################
//
// FILE: hrpwm_ex1_duty_sfo.c
//
// TITLE: HRPWM Duty Control with SFO.
//
//! \addtogroup driver_example_list
//! <h1>HRPWM Duty Control with SFO</h1>
//!
//! This example modifies the MEP control registers to show edge displacement
//! for high-resolution period with ePWM in Up count mode
//! due to the HRPWM control extension of the respective ePWM module.
//!
//! This example calls the following TI's MEP Scale Factor Optimizer (SFO)
//! software library V8 functions:
//!
//! \b int \b SFO(); \n
//! - updates MEP_ScaleFactor dynamically when HRPWM is in use
//! - updates HRMSTEP register (exists only in EPwm1Regs register space)
//! with MEP_ScaleFactor value
//! - returns 2 if error: MEP_ScaleFactor is greater than maximum value of 255
//! (Auto-conversion may not function properly under this condition)
//! - returns 1 when complete for the specified channel
//! - returns 0 if not complete for the specified channel
//!
//! This example is intended to explain the HRPWM capabilities. The code can be
//! optimized for code efficiency. Refer to TI's Digital power application
//! examples and TI Digital Power Supply software libraries for details.
//!
//! \b External \b Connections \n
//! - Monitor ePWM1/2/3/4 A/B pins on an oscilloscope.
//
//#############################################################################
//
//
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//#############################################################################
//
// Included Files
//
#include "driverlib.h"
#include "device.h"
#include "board.h"
#include "SFO_V8.h"
#define EPWM_TIMER_TBPRD 100UL
#define MIN_HRPWM_DUTY_PERCENT 4.0/((float32_t)EPWM_TIMER_TBPRD)*100.0
//
// Defines
//
#define LAST_EPWM_INDEX_FOR_EXAMPLE 5
#define LOAD_MODE 1
//
// Globals
//
float32_t dutyFine = MIN_HRPWM_DUTY_PERCENT;
uint16_t status;
int MEP_ScaleFactor; // Global variable used by the SFO library
// Result can be used for all HRPWM channels
// This variable is also copied to HRMSTEP
// register by SFO() function.
volatile uint32_t ePWM[] =
{0, myEPWM1_BASE, myEPWM2_BASE, myEPWM3_BASE, myEPWM4_BASE};
//
// Function Prototypes
//
void initHRPWM(uint32_t period);
void error(void);
//__interrupt void epwm1ISR(void);
//__interrupt void epwm2ISR(void);
//__interrupt void epwm3ISR(void);
//__interrupt void epwm4ISR(void);
//
// Main
//
void main(void)
{
uint16_t i = 0;
//
// Initialize device clock and peripherals
//
Device_init();
//
// Disable pin locks and enable internal pull ups.
//
Device_initGPIO();
//
// Initialize PIE and clear PIE registers. Disables CPU interrupts.
//
Interrupt_initModule();
//
// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
//
Interrupt_initVectorTable();
//
// Assign the interrupt service routines to ePWM interrupts
//
//Interrupt_register(INT_EPWM1, &epwm1ISR);
//Interrupt_register(INT_EPWM2, &epwm2ISR);
//Interrupt_register(INT_EPWM3, &epwm3ISR);
//Interrupt_register(INT_EPWM4, &epwm4ISR);
//
// Initialize the EPWM GPIO Pins and change the XBAR inputs from using GPIO0
//
Board_init();
//
// Calling SFO() updates the HRMSTEP register with calibrated MEP_ScaleFactor.
// HRMSTEP must be populated with a scale factor value prior to enabling
// high resolution period control.
//
while(status == SFO_INCOMPLETE)
{
status = SFO();
if(status == SFO_ERROR)
{
error(); // SFO function returns 2 if an error occurs & # of MEP
} // steps/coarse step exceeds maximum of 255.
}
//
// Disable sync(Freeze clock to PWM as well)
//
SysCtl_disablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
initHRPWM(EPWM_TIMER_TBPRD);
//
// Enable sync and clock to PWM
//
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
// Enable ePWM interrupts
//
//Interrupt_enable(INT_EPWM1);
//Interrupt_enable(INT_EPWM2);
//Interrupt_enable(INT_EPWM3);
//Interrupt_enable(INT_EPWM4);
//
// Enable Global Interrupt (INTM) and realtime interrupt (DBGM)
//
EINT;
ERTM;
for(;;)
{
//
// Sweep DutyFine
//
for(dutyFine = MIN_HRPWM_DUTY_PERCENT; dutyFine < 99.9; dutyFine += 0.01)
{
DEVICE_DELAY_US(1000);
for(i=1; i<LAST_EPWM_INDEX_FOR_EXAMPLE; i++)
{
float32_t count = (dutyFine * (float32_t)(EPWM_TIMER_TBPRD << 8))/100;
uint32_t compCount = (count);
HRPWM_setCounterCompareValue(ePWM[i], HRPWM_COUNTER_COMPARE_A, compCount);
HRPWM_setCounterCompareValue(ePWM[i], HRPWM_COUNTER_COMPARE_B, compCount);
}
//
// Call the scale factor optimizer lib function SFO()
// periodically to track for any change due to temp/voltage.
// This function generates MEP_ScaleFactor by running the
// MEP calibration module in the HRPWM logic. This scale
// factor can be used for all HRPWM channels. The SFO()
// function also updates the HRMSTEP register with the
// scale factor value.
//
status = SFO(); // in background, MEP calibration module
// continuously updates MEP_ScaleFactor
if (status == SFO_ERROR)
{
error(); // SFO function returns 2 if an error occurs & #
// of MEP steps/coarse step
} // exceeds maximum of 255.
}
}
}
//
// epwm1ISR - ePWM 1 ISR
//
//__interrupt void epwm1ISR(void)
//{
// EPWM_clearEventTriggerInterruptFlag(EPWM1_BASE);
// Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3);
//}
//
// epwm2ISR - ePWM 2 ISR
//
//__interrupt void epwm2ISR(void)
//{
// EPWM_clearEventTriggerInterruptFlag(EPWM2_BASE);
// Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3);
//}
//
// epwm3ISR - ePWM 3 ISR
//
//__interrupt void epwm3ISR(void)
//{
// EPWM_clearEventTriggerInterruptFlag(EPWM3_BASE);
// Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3);
//}
//
// epwm4ISR - ePWM 4 ISR
//
//__interrupt void epwm4ISR(void)
//{
// EPWM_clearEventTriggerInterruptFlag(EPWM4_BASE);
// Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3);
//}
void initHRPWM(uint32_t period)
{
uint16_t j;
//
// ePWM channel register configuration with HRPWM
// ePWMxA / ePWMxB toggle low/high with MEP control on Rising edge
//
for (j=1;j<LAST_EPWM_INDEX_FOR_EXAMPLE;j++)
{
EPWM_setEmulationMode(ePWM[j], EPWM_EMULATION_FREE_RUN);
//
// Set-up TBCLK
//
EPWM_setTimeBasePeriod(ePWM[j], period-1);
EPWM_setPhaseShift(ePWM[j], 0U);
EPWM_setTimeBaseCounter(ePWM[j], 0U);
//
// set duty 50% initially
//
HRPWM_setCounterCompareValue(ePWM[j], HRPWM_COUNTER_COMPARE_A, (period/2 << 8));
HRPWM_setCounterCompareValue(ePWM[j], HRPWM_COUNTER_COMPARE_B, (period/2 << 8));
//
// Set up counter mode
//
EPWM_setTimeBaseCounterMode(ePWM[j], EPWM_COUNTER_MODE_UP);
EPWM_disablePhaseShiftLoad(ePWM[j]);
EPWM_setClockPrescaler(ePWM[j],
EPWM_CLOCK_DIVIDER_1,
EPWM_HSCLOCK_DIVIDER_1);
EPWM_setSyncOutPulseMode(ePWM[j], EPWM_SYNC_OUT_PULSE_DISABLED);
//
// Set up shadowing
//
#if (LOAD_MODE == 0)
EPWM_setCounterCompareShadowLoadMode(ePWM[j],
EPWM_COUNTER_COMPARE_A,
EPWM_COMP_LOAD_ON_CNTR_ZERO);
EPWM_setCounterCompareShadowLoadMode(ePWM[j],
EPWM_COUNTER_COMPARE_B,
EPWM_COMP_LOAD_ON_CNTR_ZERO);
#else
EPWM_setCounterCompareShadowLoadMode(ePWM[j],
EPWM_COUNTER_COMPARE_A,
EPWM_COMP_LOAD_ON_CNTR_PERIOD);
EPWM_setCounterCompareShadowLoadMode(ePWM[j],
EPWM_COUNTER_COMPARE_B,
EPWM_COMP_LOAD_ON_CNTR_PERIOD);
#endif
//
// Set actions
//
EPWM_setActionQualifierAction(ePWM[j],
EPWM_AQ_OUTPUT_A,
EPWM_AQ_OUTPUT_HIGH,
EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);
EPWM_setActionQualifierAction(ePWM[j],
EPWM_AQ_OUTPUT_B,
EPWM_AQ_OUTPUT_HIGH,
EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);
EPWM_setActionQualifierAction(ePWM[j],
EPWM_AQ_OUTPUT_A,
EPWM_AQ_OUTPUT_LOW,
EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
EPWM_setActionQualifierAction(ePWM[j],
EPWM_AQ_OUTPUT_B,
EPWM_AQ_OUTPUT_LOW,
EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPB);
HRPWM_setMEPEdgeSelect(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_CTRL_FALLING_EDGE);
HRPWM_setMEPControlMode(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_DUTY_PERIOD_CTRL);
#if (LOAD_MODE == 0)
HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_A, HRPWM_LOAD_ON_CNTR_ZERO);
#else
HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_A, HRPWM_LOAD_ON_CNTR_PERIOD);
#endif
HRPWM_setMEPEdgeSelect(ePWM[j], HRPWM_CHANNEL_B, HRPWM_MEP_CTRL_FALLING_EDGE);
HRPWM_setMEPControlMode(ePWM[j], HRPWM_CHANNEL_B, HRPWM_MEP_DUTY_PERIOD_CTRL);
#if (LOAD_MODE == 0)
HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_B, HRPWM_LOAD_ON_CNTR_ZERO);
#else
HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_B, HRPWM_LOAD_ON_CNTR_PERIOD);
#endif
HRPWM_enableAutoConversion(ePWM[j]);
//
// Turn off high-resolution period control.
//
HRPWM_disablePeriodControl(ePWM[j]);
HRPWM_disablePhaseShiftLoad(ePWM[j]);
//
// Interrupt where we will change the Compare Values
// Select INT on Time base counter zero event,
// Enable INT, generate INT on 1st event
//
//EPWM_setInterruptSource(ePWM[j], EPWM_INT_TBCTR_ZERO);
//EPWM_enableInterrupt(ePWM[j]);
//EPWM_setInterruptEventCount(ePWM[j], 1U);
}
}
//
// error - Halt debugger when called
//
void error (void)
{
ESTOP0; // Stop here and handle error
}
