Size RFFT-ADC Example on F28335

Jonatan Vanegas

Hi all,

I'm doing a project that use FFT. I have been working with the example from FPU library ("2833x_RFFT_ADC_RT") and the result is very good with 512 samples but when I change stages number to 11 (2^11=2048) I have this error:

line 127: error:
program will not fit into available memory. run placement with
alignment/blocking fails for section ".ebss" size 0x3089 page 1. Available

memory ranges:
>> Compilation failure
RAML2 size: 0x1000 unused: 0x1000 max hole: 0x1000
warning: entry-point symbol other than "_c_int00" specified: "code_start"
error: errors encountered during linking; "2833x_RFFT_ADC_RT.out" not built

How could I fix this?. I don't have experience in memory management but I think there is space avaliable because when I compile ("2833x_RFFT") project and I change size fft to 2048 works fine.

Thank you for any suggestion,

Jonatan

over 9 years ago

0 Vishal_Coelho over 9 years ago

TI__Mastermind 20850 points

Hi Jonatan,

Jonatan Vanegas said:
line 127: error:
program will not fit into available memory. run placement with
alignment/blocking fails for section ".ebss" size 0x3089 page 1. Available

.ebss is too large to fit in any memory, you will exssentially have to club together some of the RAM blocks to fit this section

   RAML0L3     : origin = 0x008000, length = 0x004000



Comment out the definitions for RAMs L1,L2,L3 if you are doing the above.

Then just allocate .ebss to this new memory block.

0 Jonatan Vanegas over 9 years ago in reply to Vishal_Coelho

Prodigy 150 points

Hi Vishal

Thanks for you reply,

I did what you said and It helped me a lot. I have other question about proccesing. In this example, I am working with 10,24 kHz sampling frequency, namely I have 1/10,24Khz=97us for The CPU computes 2048 Point FFT before next 2048 samples fill buffer again. but from FPU documentacion it says 2048 point FFT takes 65000 cycles and 85000 cycles to compute FFT magnitud and I only have 97us/6,6ns=14697 cycles machine to do this. According to this, could not CPU compute 2048 points FFT before 2048 samples come in again? Does F28335 sampling and proccesing simultaneously?

Thanks

Jonatan

0 Vishal_Coelho over 9 years ago in reply to Jonatan Vanegas

TI__Mastermind 20850 points

Jonatan Vanegas said:
Does F28335 sampling and proccesing simultaneously?

I think you can setup the DMA to buffer the ADC samples while the C28x does the magnitude processing, as long as they are different buffers (and possible different physical RAM blocks - you will have to check the DMA guide for details on this)

0 Jonatan Vanegas over 9 years ago in reply to Vishal_Coelho

Prodigy 150 points

Hi Vishal

Thanks for you reply,

Sorry for my delay. I have been working in DMA controller as you said and I think I have a program that works already. However, I don't see how I can check Whether samples transfering and proccesing are doing simultaneously.

1. Is there any way or tool in CCS for check this? this is a part of my program. I am sampling 2 channels and I get 128 samples for aech one.

void main(void)

{

………

……..

InitAdc();

AdcRegs.ADCTRL1.all = 0;

AdcRegs.ADCTRL1.bit.SEQ_CASC =1;

AdcRegs.ADCTRL1.bit.ACQ_PS =15;

AdcRegs.ADCTRL1.bit.CPS = 0; // divide by 1

AdcRegs.ADCTRL1.bit.CONT_RUN = 0; // single run mode

AdcRegs.ADCTRL2.all = 0;

AdcRegs.ADCTRL2.bit.EPWM_SOCA_SEQ1 = 1;// Enable SOCA from ePWM to start SEQ1

AdcRegs.ADCTRL2.bit.INT_ENA_SEQ1 = 1; // Enable SEQ1 interrupt (every EOS)

AdcRegs.ADCTRL2.bit.RST_SEQ1 = 1;

AdcRegs.ADCTRL3.bit.SMODE_SEL = 0x1;

AdcRegs.ADCMAXCONV.all = 0x0003;

AdcRegs.ADCCHSELSEQ1.bit.CONV00 = 0x0;

AdcRegs.ADCCHSELSEQ1.bit.CONV01 = 0x1;

AdcRegs.ADCCHSELSEQ1.bit.CONV02 = 0x2;

AdcRegs.ADCCHSELSEQ1.bit.CONV03 = 0x3;

AdcRegs.ADCCHSELSEQ2.bit.CONV04 = 0x0;

AdcRegs.ADCCHSELSEQ2.bit.CONV05 = 0x1;

AdcRegs.ADCCHSELSEQ2.bit.CONV06 = 0x2;

AdcRegs.ADCCHSELSEQ2.bit.CONV07 = 0x3;

EPwm1Regs.ETSEL.bit.SOCAEN = 1; // Enable SOC on A group

EPwm1Regs.ETSEL.bit.SOCASEL = 4; // Select SOC from from CPMA on upcount

EPwm1Regs.ETPS.bit.SOCAPRD = 1; // Generate pulse on 1st event

EPwm1Regs.CMPA.half.CMPA = 0x0080; // Set compare A value

EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT

EPwm1Regs.TBPRD = ADC_SAMPLE_PERIOD;//0xFFFF; // Set period for ePWM1

EPwm1Regs.TBCTL.bit.CTRMODE = 0; //

DMAInitialize();

//Configure DMA Channel

DMADest = &RFFTINPUT[0]; //Point DMA destination to the beginning of the array

DMASource = &AdcMirror.ADCRESULT0;//Point DMA source to ADC result register base

DMACH1AddrConfig(DMADest,DMASource);

DMACH1BurstConfig(7,1,128);

DMACH1TransferConfig(127,1,0);

DMACH1WrapConfig(1,0,0,1);

DMACH1ModeConfig(DMA_SEQ1INT,PERINT_ENABLE,ONESHOT_DISABLE,CONT_DISABLE,SYNC_DISABLE,SYNC_SRC,OVRFLOW_DISABLE,SIXTEEN_BIT,CHINT_END,CHINT_ENABLE);

StartDMACH1();

//--- Main Loop

while(1){ // endless loop - wait for an interrupt

if(FFTStartFlag){ // If one frame data ready, then do FFT

contador++;

//*******************Canal 1**************

for(c=0;c<RFFT_SIZE;c++)

AdcBuf[c]= RFFTINPUT[c];

RFFT_adc_f32(&rfft_adc);

RFFT_f32_mag(&rfft); // Calculate spectrum amplitude

RFFT_f32_phase(&rfft);

for(c=0;c<RFFT_SIZE/2+1;c++){

RFFTmag1[c]= RFFTmagBuff[c]*FACTOR_ESCALA;

RFFTpha1[c]= RFFTphaBuff[c];

}//********************************************

//****************Canal 2*********************

for(c=0;c<RFFT_SIZE;c++)

AdcBuf[c]= RFFTINPUT[c+128];

RFFT_adc_f32(&rfft_adc);

RFFT_f32_mag(&rfft); // Calculate spectrum amplitude

RFFT_f32_phase(&rfft);

for(c=0;c<RFFT_SIZE/2+1;c++){

RFFTmag2[c]= RFFTmagBuff[c]*FACTOR_ESCALA;

RFFTpha2[c]= RFFTphaBuff[c];

}//********************************************

………

……….

FFTStartFlag=0;

}

interrupt void local_DINTCH1_ISR(void) // DMA Channel 1

{

contador_1++;

// To receive more interrupts from this PIE group, acknowledge this interrupt

PieCtrlRegs.PIEACK.all = PIEACK_GROUP7;

FFTStartFlag=1;

StartDMACH1();

return;

}

2. In order to minimize computational load. I think I could modify RFFT_f32_mag and RFFT_f32_phase funtions due to I don't need all N/2 values that come from them and I only need the first 20 values. Unfortunately, I dont know asembly lenguage and I dont know how do it.

Could you help me out?

Thank for you Valuable help

Jonatan

C2000™︎ microcontrollers

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Size RFFT-ADC Example on F28335