TMS320F28377S: SFRA Question

user5624527

Part Number: TMS320F28377S
Other Parts Discussed in Thread: CONTROLSUITE, SFRA

At the BUCK example project of F28377S (C:\ti\controlSUITE\development_kits\BOOSTXL_BUCKCONV\v1_01_00_00\Buck_VMC_F2837xS)

#include "Buck_VMC-Settings.h"

#include "F28x_Project.h"

#define MATH_TYPE 1 //FLOAT_MATH

#include "DPlib.h"

#include "IQmathLib.h"

#include "SFRA_F_Include.h"

#define SFRA_ISR_FREQ 200000

#define SFRA_FREQ_START 100

#define SFRA_FREQ_LENGTH 100

//SFRA step Multiply = 10^(1/No of steps per decade(35))

#define SFREQ_STEP_MULTIPLY (float)1.0680004

I want to know how does the formula (red mark) come from? Or what "No of steps per decade" means? Why it is 35 in the formula?

over 8 years ago

0 Manish Bhardwaj over 8 years ago

TI__Mastermind 43730 points

It comes from log 10, basically, we want 35 steps in a decade i.e. as frequency goes from 1 to 10, or 10 to 100,

With some math's if we create a frequency vector that multiplied the frequency point where FRA is performed by 10 ^(1/ no of steps), you will get no of steps in a decade of frequency.

This is done because bode is plotted on Log10 scale..

0 user5624527 over 8 years ago in reply to Manish Bhardwaj

Intellectual 800 points

I am a Chinese, and I don't very understand the parameter of "No of steps per decade". Can you explain more about the meaning of "decade" . Is it mean "ten years" or "Tenfold"? Or other meanings?
And do you have any instruction documents that can explain it detailed?

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28377S: SFRA Question