Using cFFT library NRF_LOG stop with Hardfault_Handler

[ricardo vasquez rossi]

HI

SDK-15 - NRF52840

I'm using SAADC example of the SDK.

I read the ADC values and I make an matrix to calculate FFT using the CMSIS library..

the problem is when I print the data after using DSP library (FFT), the program stuck, in dissasembly window appear:

Before to use the Library, NRF_LOG works fine.

HardFault_Handler:
0x15ee: 0xe7fe B.N HardFault_Handler ; 0x15ee

I have the following code:

 for ( int y = 0; y < SAMPLES_IN_BUFFER; y++)
           {
             Incomplex[y*2]=vibdata[y];
             Incomplex[y*2+1]=0;
             NRF_LOG_RAW_INFO("%d,", Incomplex[y]);  
             NRF_LOG_FLUSH(); 
           }
 
    arm_cfft_q15(&RealFFT_Instance,(q15_t *)Incomplex,0,1);

    arm_cmplx_mag_q15((q15_t *)Incomplex,fftvibout,SAMPLES_IN_BUFFER);
         
    for ( int y = 0; y < SAMPLES_IN_BUFFER; y++)  
     {
         NRF_LOG_RAW_INFO("%d,", fftvibout[y]);  // ***** HERE the program STUCK in the dissasembler appear HardFault_Handler
         NRF_LOG_FLUSH(); 
     }    
         

I attached an debugger screen.

Thanks 

Ricardo

[ricardo vasquez rossi]

Dear Nordik Team

Finally, i have spent a lot of time trying to fidn a solution, I got it..
The error was the position of INICIALITACION OF THE INSTANCE FFT...(arm_cfft_instance_q15   RealFFT_Instance;   )

Before initialization of the variable, it was located in the Saadc_callback function..

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
  ret_code_t err_code;
  int cycle=6;

  ******* HERE WAS THE INSTANCE FFT INICIALITATION ****** I moved to #defined zone of the program
  
  if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
  {
    
    memset(p_event->data.done.p_buffer, 0, sizeof p_event->data.done.p_buffer);
    err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);

After, I moved it to at the begining of the program

#include "nrf_log_default_backends.h"
#include "arm_const_structs.h"
#include <arm_math.h>

#define SAMPLES_IN_BUFFER 1024//512

volatile uint8_t state = 1;

int e, value,  amp ;
float soundVolMax, soundVolAvg, soundVolRMS, soundVolRMSflt;
float soundVolMaxR, soundVolAvgR, soundVolRMSR, soundVolRMSfltR;
float dB;
int AmpMax = SAMPLES_IN_BUFFER;
int MicSamples = SAMPLES_IN_BUFFER;
float signalMin, signalMax, signalAvg;
float difA,difB,difC;

int16_t vibdata[SAMPLES_IN_BUFFER], Incomplex[SAMPLES_IN_BUFFER*2],fftvibout[SAMPLES_IN_BUFFER*2];  

// HERE position 2
arm_cfft_instance_q15   RealFFT_Instance;   // ***** HERE MOVED THE INICIALITATION  **** **



static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(0);
static nrf_saadc_value_t     m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t     m_ppi_channel;
static uint32_t              m_adc_evt_counter;

Another problem, I realized,  the result of the FFT function all time give me a different result, i saw it in the "Live watch" in the screen shot.

But it corrected when the instance was moved to the beginning of the program.

Best Regards

Ricardo