[RM48] generating floating point duty cycle issue

Manjunathan K

Hi,

I tried to generate PWM signal with floating point duty cycle. but it is not working. the floating point is getting truncated because uint32 duty declaration.

how to solve this problem. Please support to short out the problem. for the reference i have attached the project also.

#include "sys_common.h"

#include "het.h"

static const float s_het1pwmPolarity[8U] = { 3U, 3U, 3U, 3U, 3U, 3U, 3U, 3U, };

void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty,

uint32 pwmdutty);

hetSIGNAL_t setup_pwm;

void main(void)

{

hetInit();

setup_pwm.period = (float64)1e6/5000;//5khz

uint32 Dutcycle = setup_pwm.period*0.085;

uint32 Porcentdutty=0.085*100;

pwmSetSignal(hetRAM1, pwm0, setup_pwm);

pwmSetDuty_full(hetRAM1, pwm0, Porcentdutty, Dutcycle);

pwmStart(hetRAM1, pwm0);

while(1);

}

void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty,

uint32 pwmdutty) {

uint32 action;

uint32 pwmPolarity = 0U;

uint32 var;

if (hetRAM == hetRAM1) {

pwmPolarity = s_het1pwmPolarity[pwm];

}

if (fuse_pwmDuty == 0U) {

action = (pwmPolarity == 3U) ? 0U : 2U;

} else if (fuse_pwmDuty >= 100U) {

action = (pwmPolarity == 3U) ? 2U : 0U;

} else {

action = pwmPolarity;

}

//var = (uint32) pwmdutty * 1.2613; //((pwmPeriod * pwmDuty) / 100U)

var = (float64) pwmdutty * 0.86;

hetRAM->Instruction[(pwm << 1U) + 41U].Control = ((hetRAM->Instruction[(pwm

<< 1U) + 41U].Control) & (~(uint32) (0x00000018U)))

| (action << 3U);

hetRAM->Instruction[(pwm << 1U) + 41U].Data = (var << 7U) + 128U;

}

4747.dty1.rar

#include "sys_common.h"#include "het.h"

static const float s_het1pwmPolarity[8U] = { 3U, 3U, 3U, 3U, 3U, 3U, 3U, 3U, };void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty, uint32 pwmdutty);

hetSIGNAL_t setup_pwm;
void main(void){ hetInit();
setup_pwm.period = (float64)1e6/5000;//5khz uint32 Dutcycle = setup_pwm.period*0.085; uint32 Porcentdutty=0.085*100; pwmSetSignal(hetRAM1, pwm0, setup_pwm); pwmSetDuty_full(hetRAM1, pwm0, Porcentdutty, Dutcycle); pwmStart(hetRAM1, pwm0);
while(1);}
void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty, uint32 pwmdutty) { uint32 action; uint32 pwmPolarity = 0U; uint32 var;
if (hetRAM == hetRAM1) { pwmPolarity = s_het1pwmPolarity[pwm]; }
if (fuse_pwmDuty == 0U) { action = (pwmPolarity == 3U) ? 0U : 2U; } else if (fuse_pwmDuty >= 100U) { action = (pwmPolarity == 3U) ? 2U : 0U; } else { action = pwmPolarity; } //var = (uint32) pwmdutty * 1.2613; //((pwmPeriod * pwmDuty) / 100U) var = (float64) pwmdutty * 0.86; hetRAM->Instruction[(pwm << 1U) + 41U].Control = ((hetRAM->Instruction[(pwm << 1U) + 41U].Control) & (~(uint32) (0x00000018U))) | (action << 3U); hetRAM->Instruction[(pwm << 1U) + 41U].Data = (var << 7U) + 128U;
}

over 9 years ago

0 Manjunathan K over 9 years ago

Expert 2825 points

also attached the image result of oscilloscope-related to above post

0 Anthony F. Seely over 9 years ago in reply to Manjunathan K

TI__Guru 68940 points

So I don't know where you are seeing the issue, but you are right that the HET hardware takes the duty cycle as an integer which signifies the number of HET HR clocks for the duty cycle. If you are seeing an issue doing the math in floating point - you can always change the code to used integer math.

0 Manjunathan K over 9 years ago in reply to Anthony F. Seely

Expert 2825 points

Thank you Mr.Antony

Sir, I dint understand what you mean by change the code to used integr math.

Thanks and regards

K.Manjunathan

PSGIAS

0 Anthony F. Seely over 9 years ago in reply to Manjunathan K

TI__Guru 68940 points

Manjunathan,

I guess what I mean is that it's math - nothing complicated or specific to the hardware.

For a duty cycle, you need to compute an integer value between 0 and "P" where P is the count in cycles for the pwm period.

So if the math that is being done doesn't give you proper values in this range - you just need to fix the math. Has nothing do do with the hardware.

I can't just spot from looking at the code where the math is going wrong - I would suggest that you step through the computation with the debugger and try to understand where you are losing precision or range.

0 Manjunathan Karuppaswamy over 9 years ago in reply to Anthony F. Seely

Prodigy 10 points

Thank you Sir,

I will do it and come back to you if i have any struggle.

0 Manjunathan K over 9 years ago in reply to Anthony F. Seely

Expert 2825 points

Hi sir.

i have checked the math calculations,there is now problem with it. The problem is in pwmSetDuty_full function.

void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty,

uint32 pwmdutty);

uint32 Dutcycle

uint32 Porcentdutty

fuse_pwmduty and pwmdutty and also Dutycycle and Porcentdutty are declared as integer. I tried to change the functions but iagain errors are generated.

how to solve this problem

void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty, uint32 pwmdutty);void pwmSetDuty_full(hetRAMBASE_t * hetRAM, uint32 pwm, uint32 fuse_pwmDuty, uint32 pwmdutty);

0 Anthony F. Seely over 9 years ago in reply to Manjunathan K

TI__Guru 68940 points

Manjunathan,

All that the error #148 means is that in the header file, you have a different signature (or prototype) for this function.

You need the header file and the .c file to match. If you change the type of a parameter in the .c file, you also need to change it in the .h file prototype.

0 Manjunathan K over 9 years ago in reply to Anthony F. Seely

Expert 2825 points

Thank you Sir,

I got the expected output. once again thank you for the continuous support.

regards

K.Manjunathan

PSG IAS.

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[RM48] generating floating point duty cycle issue