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% data file loaded by prbs_scr.m
% speed filter not in feedback, but in forward loop at input to PI
% control.
% btremaine 2022

U = [
-5	-3861
-5	-3878
-5	-3911
5	-3949

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%% prbs.m -- analysis of bode using u(k) and y(k)
% load data, should be >> 2^15 values so transient dies out
% btremaine 2022

% run m file to load data (prbs_data7, 8, 9
prbs_data9


% grab last 32767 data points
N= length(U);

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	  /* Run the speed control loop ================================ */
    /*   this code part of speed_torq_cntrl.c                      */

	  /* Compute speed error */
	  hTargetSpeed = ( int16_t )( wCurrentReference / 65536 );
	  // Uses Moving Average Filter updated every PWM period
	  // and averaged for xxxx samples
	  hMeasuredSpeed = SPD_GetAvrgMecSpeedUnit( pHandle->SPD );

/* system ID */

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// replicated from wikipeda, https://en.wikipedia.org/wiki/Pseudorandom_binary_sequence
// Example of PRBS7
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
    
int main(int argc, char* argv[]) {
    uint8_t start = 0x02;
    uint8_t a = start;
    int i;    

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Prbs_t is a struct used in the prbs function:
typedef struct
{
uint16_t start; // start LFSR value
uint16_t lfsr; // LFSR current register
uint16_t index; // LFSR index
uint16_t newbit; // current newbit
} Prbs_t;

/**

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# TremaineConsultingGroup
# Brian Tremaine
# prbs.py
# August 11, 2021
# Prototype PRBS generator
#

#   PRBS15 = x^15 + x^14 + 1   Wikipeda

#           .--->X-------------------------------------------------------->

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%% System ID Example
% Aug 5, 2021
% Uses MATLAB System ID Toolbox

%% Generate u(k)
Band= [0 1];
Range= [-1 1];      % amplitude limits
Ts=5E-3;
N=2^16-1;           % # points
% 

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/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2020 STMicroelectronics.
  * All rights reserved.</center></h2>

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/**
  * @brief This function handles DMA1 channel1 global interrupt.
  */
void DMA1_Channel1_IRQHandler(void)
{
  /* USER CODE BEGIN DMA1_Channel1_IRQn 0 */

  /* USER CODE END DMA1_Channel1_IRQn 0 */
  HAL_DMA_IRQHandler(&hdma_tim4_ch1);
  /* USER CODE BEGIN DMA1_Channel1_IRQn 1 */