TMS320F2808: Unwanted PWM pulse by adding up a DELAY() inside ADC initialisation code

Asim Dey

Part Number: TMS320F2808

Hello,

Each time ADC receives a Start-of-Conversion (SOC) request from ePWMx SOCx trigger to autosequence a series of conversions. I have confused that enabling DELAY() function inside ADC initialisation code, the unwanted PWM pulse was coming. DELAY() function used in ADC to Power UP the ADC Register bit. So, Why unwanted pulse is coming by adding the DELAY() in ADC initialisation code?

Here i'm adding two snapshot picture:
I: Before adding Delay() in AdcRegs. initialisation
II: After adding Delay() in AdcRegs. initialisation

I: Before adding Delay() in AdcRegs. initialisation

II: After adding Delay() in AdcRegs. initialisation

over 8 years ago

0 tlee over 8 years ago

TI__Guru 62975 points

Asim,

Are you resetting the device between runs?

It is possible that the ADC and EPWM are configured from a previous execution and they are still active when the Delay() function is running.

-Tommy

0 Asim Dey over 8 years ago in reply to tlee

Expert 2195 points

Hello Lee,

I am not using any 'resetting' register bit to reset device from running condition.

If not use DELAY (), then EPWM is generate proper pulses, and once i used the DELAY (), EPWM is not generate the proper pulse?

0 Asim Dey over 8 years ago

Expert 2195 points

Anyone else can be help me to rectify this problem, why the unwanted PWM pulses coming after using the DELAY () in ADC peripheral?

0 tlee over 8 years ago in reply to Asim Dey

TI__Guru 62975 points

Asim,

Sorry, I missed your first reply. Can you try to explicitly reset the device before loading the program?

What order are you initializing the ADC and EPWM? Can you switch the order to see if it makes a difference?

-Tommy

0 Asim Dey over 8 years ago in reply to tlee

Expert 2195 points

Hello Lee,

I have followed your above assumption but not work, still its coming unwanted PWM pulse of after DELAY() function enabled.

0 tlee over 8 years ago in reply to Asim Dey

TI__Guru 62975 points

Asim,

Can you attach your initialization code with the Use rich formatting -> Attach / Insert File function?

-Tommy

0 Asim Dey over 8 years ago in reply to tlee

Expert 2195 points

Hello Lee,

Here inserting the initialisation ADC peripheral code for voltage measurement:

Fullscreen TestADCVoltage1.c Download

// Configuring ADC peripheral of voltage measurement

#include "stdio.h"
#include "stdlib.h"
#include "DSP280x_Device.h"
#include "DSP280x_Examples.h"

// Prototype
void init_system(void);
void init_adc(void);
void init_epwm1(void);
__interrupt void adc_isr(void);

#define ADC_usDELAY  5000L

// Global Variable
unsigned int Va0;

void main(void)
{
	
	init_system();
	
}

void init_system(void)
{
//Step1: Initialize System Control Peripheral Clock:
 	EALLOW;
	SysCtrlRegs.WDKEY = 0x0055;
	SysCtrlRegs.WDKEY = 0x00AA;
	SysCtrlRegs.PLLSTS.bit.MCLKSTS = 0;		// Normal condition (Device not in limp mode) 
	SysCtrlRegs.PLLSTS.bit.CLKINDIV = 0;		// CLKIN divide by 2 is enabled
	SysCtrlRegs.PLLSTS.bit.MCLKOFF = 1;		// Oscillator fail-detect logic is disabled (PLL not issue limp-mode clock)
	SysCtrlRegs.PLLSTS.bit.PLLLOCKS = 0;		// PLL is lock & CPU is clocked by OSCCLK/2
	SysCtrlRegs.HISPCP.bit.HSPCLK = 2;		// HSPCLK=SYSCLKOUT/4 (i.e 100/4=25MHz)
	SysCtrlRegs.LOSPCP.bit.LSPCLK = 0;		// LSPCLK=SYSCLKOUT

	SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1;		// Enable clock 
	SysCtrlRegs.PCLKCR1.bit.EPWM1ENCLK = 1;		// Enable clock for ePWM1
	SysCtrlRegs.PCLKCR0.bit.ADCENCLK = 1;		// Enable clock for ADC
	EDIS;
//Step2: Initialize GPIO Pins:
	EALLOW;
	GpioCtrlRegs.GPAPUD.bit.GPIO0 = 0;		// enable pull-up
	GpioCtrlRegs.GPADIR.bit.GPIO0 = 1;		// output
	GpioDataRegs.GPASET.bit.GPIO0 = 1;
	GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;		// ePWM1A, board pin=9
	EDIS;
//Step3: Clear all interrupts and initialize PIE vector table:
   	IER = 0x0000;					// Disable CPU interrupts
   	IFR = 0x0000;					// clear all CPU interrupt flags
   	EALLOW;
   	PieVectTable.ADCINT = &adc_isr;			// Initialize PIE Vector Table of ADC
   	EDIS;
//Step4: Initialize all the Device Peripherals:
   	init_epwm1();
   	init_adc();
//Step5: Enable interrupts & PIE Control Register:

	PieCtrlRegs.PIEIER1.bit.INTx6 = 1;		// Enable interrupt ADCINT

	IER |= M_INT1; 	// Enable CPU Interrupt 1
	EINT;		// Enable Global interrupt INTM
	ERTM;		// Enable Global real time interrupt DBGM
}

void init_epwm1(void)
{
	EPwm1Regs.TBCTL.bit.FREE_SOFT = 3;  	// free run at emul break
	EPwm1Regs.TBCTL.bit.SYNCOSEL = 1;	// count_zero
	EPwm1Regs.TBCTL.bit.CLKDIV = 0;		// CLKDIV = 1
	EPwm1Regs.TBCTL.bit.CTRMODE = 2;	// count up-down mode
	EPwm1Regs.TBCTL.bit.HSPCLKDIV = 0;	// HSPCLKDIV = 1
	EPwm1Regs.TBCTL.bit.PHSDIR = 0;		// don't care
	EPwm1Regs.TBCTL.bit.PHSEN = 0;		// disable phase in
	EPwm1Regs.TBCTL.bit.PRDLD = 0;		// reload on counter = 0
	EPwm1Regs.TBCTL.bit.SWFSYNC = 0;	// no sw force sync out
	EPwm1Regs.TBPRD = 128;			// 390.625kHz, 2.56us
	EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
	EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
	EPwm1Regs.CMPA.half.CMPA = 64;
	EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
	EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;

	EPwm1Regs.ETSEL.bit.SOCASEL = 1;	// SOCA at ZERO event
	EPwm1Regs.ETSEL.bit.SOCAEN = 1;		// enable SOCA
	EPwm1Regs.ETPS.bit.SOCAPRD = 1;		// generate SOCA on 1st event

}

void init_adc(void)
{
	// ADC Configuration
	AdcRegs.ADCREFSEL.bit.REF_SEL = 0;		// Internal reference selected
	AdcRegs.ADCTRL3.bit.ADCBGRFDN = 1;		// Power Up the Band gap & Reference Circuitry
	AdcRegs.ADCTRL3.bit.ADCPWDN = 1;        	// Power Up the ADC Analog Circuitry
	AdcRegs.ADCTRL3.bit.ADCCLKPS = 2;	 	// HSPCLK=25MHz; ADC clock: FCLK=HSPCLK / 2 * ADCCLKPS
	AdcRegs.ADCTRL3.bit.SMODE_SEL = 0;		// SEQUENTIAL sampling mode
	DELAY_US(ADC_usDELAY);				// ADC_usDELAY = 5000L

	AdcRegs.ADCTRL1.bit.CPS = 0;			// 6.25MHz; ADCCLK=FCLK/1;
	AdcRegs.ADCTRL1.bit.SEQ_CASC = 1; 		// CASCADED Sequencer
	AdcRegs.ADCTRL1.bit.ACQ_PS = 15; 		// 2.56us, S/H =(ACQ_PS+1) x tADCCLK;
	AdcRegs.ADCMAXCONV.bit.MAX_CONV1 = 0;   	// 1 Conversion
	AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0; 		// ADCINA0 as input
	AdcRegs.ADCTRL1.bit.CONT_RUN = 1;		// Continuous run mode

	AdcRegs.ADCTRL2.bit.EPWM_SOCA_SEQ1 = 1;		// ePWM1 SOCA trigger for SEQ1
	AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1;		// enable SEQ1 interrupt
	
}

__interrupt void adc_isr(void)
{

	Va0 = AdcMirror.ADCRESULT0;			// store results globally

	
 	AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1;		// Clear INT SEQ1 bit
 	PieCtrlRegs.PIEACK.all = PIEACK_GROUP1; 	// Acknowledge group 1 
 	
}

0 tlee over 8 years ago in reply to Asim Dey

TI__Guru 62975 points

Asim,

Can you try the attached to see if it helps? I tried to put everything into an idle state during initialization and only started the EPWM counter at the end.

Fullscreen TestADCVoltage2.c Download

// Configuring ADC peripheral of voltage measurement

#include "stdio.h"
#include "stdlib.h"
#include "DSP280x_Device.h"
#include "DSP280x_Examples.h"

// Prototype
void init_system(void);
void init_adc(void);
void init_epwm1(void);
__interrupt void adc_isr(void);

#define ADC_usDELAY  5000L

// Global Variable
unsigned int Va0;

void main(void)
{
	
	init_system();
	
}

void init_system(void)
{
//Step1: Initialize System Control Peripheral Clock:
 	EALLOW;
	SysCtrlRegs.WDKEY = 0x0055;
	SysCtrlRegs.WDKEY = 0x00AA;
	SysCtrlRegs.PLLSTS.bit.MCLKSTS = 0;		// Normal condition (Device not in limp mode) 
	SysCtrlRegs.PLLSTS.bit.CLKINDIV = 0;		// CLKIN divide by 2 is enabled
	SysCtrlRegs.PLLSTS.bit.MCLKOFF = 1;		// Oscillator fail-detect logic is disabled (PLL not issue limp-mode clock)
	SysCtrlRegs.PLLSTS.bit.PLLLOCKS = 0;		// PLL is lock & CPU is clocked by OSCCLK/2
	SysCtrlRegs.HISPCP.bit.HSPCLK = 2;		// HSPCLK=SYSCLKOUT/4 (i.e 100/4=25MHz)
	SysCtrlRegs.LOSPCP.bit.LSPCLK = 0;		// LSPCLK=SYSCLKOUT

	SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1;		// Enable clock 
	SysCtrlRegs.PCLKCR1.bit.EPWM1ENCLK = 1;		// Enable clock for ePWM1
	SysCtrlRegs.PCLKCR0.bit.ADCENCLK = 1;		// Enable clock for ADC
	EDIS;
//Step2: Initialize GPIO Pins:
	EALLOW;
	GpioCtrlRegs.GPAPUD.bit.GPIO0 = 0;		// enable pull-up
	GpioCtrlRegs.GPADIR.bit.GPIO0 = 1;		// output
	GpioDataRegs.GPASET.bit.GPIO0 = 1;
	GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;		// ePWM1A, board pin=9
	EDIS;
//Step3: Clear all interrupts and initialize PIE vector table:
	EPwm1Regs.TBCTL.bit.CTRMODE = 3;  // Freeze EPWM
	AdcRegs.ADCTRL1.bit.RESET = 1;    // Reset ADC

   	IER = 0x0000;					// Disable CPU interrupts
   	IFR = 0x0000;					// clear all CPU interrupt flags
   	EALLOW;
   	PieVectTable.ADCINT = &adc_isr;			// Initialize PIE Vector Table of ADC
   	EDIS;
//Step4: Initialize all the Device Peripherals:

   	init_adc();
	init_epwm1();
//Step5: Enable interrupts & PIE Control Register:

	IER |= M_INT1; 	// Enable CPU Interrupt 1
	EINT;		// Enable Global interrupt INTM
	ERTM;		// Enable Global real time interrupt DBGM

    PieCtrlRegs.PIEIER1.bit.INTx6 = 1;		// Enable interrupt ADCINT
	EPwm1Regs.TBCTL.bit.CTRMODE = 2;	// count up-down mode
}

void init_epwm1(void)
{
	EPwm1Regs.TBCTL.bit.FREE_SOFT = 3;  	// free run at emul break
	EPwm1Regs.TBCTL.bit.SYNCOSEL = 1;	// count_zero
	EPwm1Regs.TBCTL.bit.CLKDIV = 0;		// CLKDIV = 1
//	EPwm1Regs.TBCTL.bit.CTRMODE = 2;	// count up-down mode
	EPwm1Regs.TBCTL.bit.HSPCLKDIV = 0;	// HSPCLKDIV = 1
	EPwm1Regs.TBCTL.bit.PHSDIR = 0;		// don't care
	EPwm1Regs.TBCTL.bit.PHSEN = 0;		// disable phase in
	EPwm1Regs.TBCTL.bit.PRDLD = 0;		// reload on counter = 0
	EPwm1Regs.TBCTL.bit.SWFSYNC = 0;	// no sw force sync out
	EPwm1Regs.TBPRD = 128;			// 390.625kHz, 2.56us
	EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
	EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
	EPwm1Regs.CMPA.half.CMPA = 64;
	EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
	EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;

	EPwm1Regs.ETSEL.bit.SOCASEL = 1;	// SOCA at ZERO event
	EPwm1Regs.ETSEL.bit.SOCAEN = 1;		// enable SOCA
	EPwm1Regs.ETPS.bit.SOCAPRD = 1;		// generate SOCA on 1st event

}

void init_adc(void)
{
	// ADC Configuration
	AdcRegs.ADCREFSEL.bit.REF_SEL = 0;		// Internal reference selected
	AdcRegs.ADCTRL3.bit.ADCBGRFDN = 1;		// Power Up the Band gap & Reference Circuitry
	AdcRegs.ADCTRL3.bit.ADCPWDN = 1;        	// Power Up the ADC Analog Circuitry
	AdcRegs.ADCTRL3.bit.ADCCLKPS = 2;	 	// HSPCLK=25MHz; ADC clock: FCLK=HSPCLK / 2 * ADCCLKPS
	AdcRegs.ADCTRL3.bit.SMODE_SEL = 0;		// SEQUENTIAL sampling mode

	AdcRegs.ADCTRL1.bit.CPS = 0;			// 6.25MHz; ADCCLK=FCLK/1;
	AdcRegs.ADCTRL1.bit.SEQ_CASC = 1; 		// CASCADED Sequencer
	AdcRegs.ADCTRL1.bit.ACQ_PS = 15; 		// 2.56us, S/H =(ACQ_PS+1) x tADCCLK;
	AdcRegs.ADCMAXCONV.bit.MAX_CONV1 = 0;   	// 1 Conversion
	AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0; 		// ADCINA0 as input
	AdcRegs.ADCTRL1.bit.CONT_RUN = 1;		// Continuous run mode

    DELAY_US(ADC_usDELAY);				// ADC_usDELAY = 5000L

	AdcRegs.ADCTRL2.bit.EPWM_SOCA_SEQ1 = 1;		// ePWM1 SOCA trigger for SEQ1
	AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1;		// enable SEQ1 interrupt
	
}

__interrupt void adc_isr(void)
{

	Va0 = AdcMirror.ADCRESULT0;			// store results globally

	
 	AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1;		// Clear INT SEQ1 bit
 	PieCtrlRegs.PIEACK.all = PIEACK_GROUP1; 	// Acknowledge group 1 
 	
}

-Tommy

0 Asim Dey over 8 years ago in reply to tlee

Expert 2195 points

Lee,
Same things happening, their is no change. The unwanted PWM pulses coming at GPIO ePWM1A pin.

My objective of this code is "To perform multiple conversion in ADC sequence by getting proper ePWM counter pulse". If ePWM counter pulse not proper then it can impossible to perform multiple conversions automatically at ADC.

0 tlee over 8 years ago in reply to Asim Dey

TI__Guru 62975 points

Asim,

I noticed that there are a handful of differences in your init_system() configuration vs the TI example code initialization. If I revert the system configuration to the TI example code, things seem to work fine on my setup.

I think your DELAY_US() issue might be due to the watchdog. I see that the TI example code will disable the watchdog whereas your initialization merely services it once. I would not be surprised if the watchdog might be throwing a reset during the delay.

-Tommy

0 Asim Dey over 8 years ago in reply to tlee

Expert 2195 points

Lee,
No changes, after disable the watchdog timer.

0 tlee over 8 years ago in reply to Asim Dey

TI__Guru 62975 points

Asim,

Are you using a TI board or a custom design? Can you start with the adc_soc example first to make sure that it works?

I did not see any strange behavior on my setup.

-Tommy

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TMS320F2808: Unwanted PWM pulse by adding up a DELAY() inside ADC initialisation code