Sine Data Generation Using Arduino Due

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Sine Data Generation Using for Arduino Due

Since real-time calculation is CPU demanding, a sine data array is required for better performanceuint32_t sin768[] PROGMEM= ....while x=[0:5375]; y = 127+127*(sin(2*pi/5376/*or some # you prefer depends on requirement*/))

Step 1: Generate Sine Data Array



Arduino Due have limited reference. However in order to generate 3 phase sine wave based on Arduino Uno, 1st of all, performance is not applausable due to its low MCLK (16MHz while Due is 84MHz), 2nd, it's limited GPIO can produce max 2 phase output and you need additional analogue circuit to produce the 3rd phase (C=-A-B).Following GPIO enabling was mostly based on try and trial+not helpful datasheet of SAM3X

Step 2: Enabling Parallel Output



PIOC->PIO_PER = 0xFFFFFFFE; //PIO controller PIO Enable register (refer to p656 of ATMEL SAM3X datasheet) and Arduino Due pin 33-41 and 44-51 were enabledPIOC->PIO_OER = 0xFFFFFFFE; //PIO controller output enable register, refer to p657 of ATMEL SAM3X datasheet PIOC->PIO_OSR = 0xFFFFFFFE; //PIO controller output status register, refer to p658 of ATMEL SAM3X datasheet




PIOC->PIO_OWER = 0xFFFFFFFE; //PIO output write enable register, refer to p670 of ATMEL SAM3X datasheet//PIOA->PIO_PDR = 0x30000000; //optional as insurance, does not seem to affect performance, digital pin 10 connect to both PC29 and PA28, digital pin 4 connect to both PC29 and PA28, here to disable disable PIOA #28 & 29




To maximize its performance, CPU load should be as low as possible. However due to the non-1to1 correspondence between the CPU pin and the Due pin, bit operation is necessary.

Step 3: Enabling Interrupt



void TC7_Handler(void){ TC_GetStatus(TC2,1);t = t%samples; //use t%samples instead of 'if' to avoid overflow of tphaseAInc = (preset*t)%5376; //use %5376 to avoid array index overflowphaseBInc = (phaseAInc+1792)%5376;phaseCInc = (phaseAInc+3584)%5376;p_A = sin768[phaseAInc]<<1; //refer to PIOC: PC1 to PC8, corresponding Arduino Due pin: pin 33-40, hence shift left for 1 digit




p_B = sin768[phaseBInc]<<12; //refer to PIOC: PC12 to PC19, corresponding Arduino Due pin: pin 51-44, hence shift left 12 digitp_C = sin768[phaseCInc]; //phase C output employe PIOC: PC21, PC22, PC23, PC24, PC25,PC26, PC28 and PC29, corresponding Arduino Due pin: digital pin: 9,8,7,6,5,4,3,10, respectively




p_C2 = (p_C&B11000000)<<22; //this generates PC28 and PC29p_C3 = (p_C&B00111111)<<21; //this generates PC21-PC26p_C = p_C2|p_C3; //this generates parallel output of phase Cp_A = p_A|p_B|p_C; //32 bit output = phase A (8bit)|phase B|phase CPIOC->PIO_ODSR = p_A; //output register =p_At++; }




build 3x8bit R/2R DAC, loads of ref on google.

Step 4: R/2R DAC



#define _BV(x) (1<<(x));uint32_t sin768[] PROGMEM= /* x=[0:5375]; y = 127+127*(sin(2*pi/5376)) */uint32_t p_A,p_B,p_C,p_C2,p_C3; //phase A phase B phase C value--though output are 8bits only, p_A and p_B value will be operated to generate a new 32 bit value in order to cop with 32bit PIOC output

Step 5: Full Code



uint16_t phaseAInc, phaseBInc,phaseCInc,freq, freqNew; uint32_t interval; uint16_t samples,preset; uint32_t t = 0;void setup() {//parallel output PIOC setup: Arduino Due pin33-40 are employed as phase A output while pin 44-51 work for phase B output

Step 5: Full Code



PIOC->PIO_PER = 0xFFFFFFFE; //PIO controller PIO Enable register (refer to p656 of ATMEL SAM3X datasheet) Arduino Due pin 33-41 and 44-51 were enabledPIOC->PIO_OER = 0xFFFFFFFE; //PIO controller output enable register, refer to p657 of ATMEL SAM3X datasheetPIOC->PIO_OSR = 0xFFFFFFFE; //PIO controller output status register, refer to p658 of ATMEL SAM3X datasheet

Step 5: Full Code



PIOC->PIO_OWER = 0xFFFFFFFE; //PIO output write enable register, refer to p670 of ATMEL SAM3X datasheet//PIOA->PIO_PDR = 0x30000000; //optional as insurance, does not seem to affect performance, digital pin 10 connect to both PC29 and PA28, digital pin 4 connect to both PC29 and PA28, here to disable disable PIOA #28 & 29 //timer setuppmc_set_writeprotect(false); // disable write protection of Power Management Control registers

Step 5: Full Code



pmc_enable_periph_clk(ID_TC7); // enable peripheral clock time counter 7TC_Configure(/* clock */TC2,/* channel */1, TC_CMR_WAVE | TC_CMR_WAVSEL_UP_RC | TC_CMR_TCCLKS_TIMER_CLOCK1); //TC clock 42MHz (clock, channel, compare mode setting) TC_SetRC(TC2, 1, interval); TC_Start(TC2, 1);// enable timer interrupts on the timer TC2->TC_CHANNEL[1].TC_IER=TC_IER_CPCS; // IER = interrupt enable register TC2->TC_CHANNEL[1].TC_IDR=~TC_IER_CPCS; // IDR = interrupt disable register

Step 5: Full Code



NVIC_EnableIRQ(TC7_IRQn); // Enable the interrupt in the nested vector interrupt controller freq = 60; //initialize frequency as 60Hz preset = 21; //array index increase by 21 samples = 256; //output samples 256/cycle interval = 42000000/(freq*samples); //interrupt counts TC_SetRC(TC2, 1, interval); //start TC Serial.begin(9600); //for test purpose }

Step 5: Full Code



void checkFreq(){ freqNew = 20000 ;if (freq == freqNew) {} else{ freq = freqNew;if (freq>20000) {freq = 20000; /*max frequency 20kHz*/};if (freq<1) {freq = 1; /*min frequency 1Hz*/};if (freq>999) {preset = 384; samples = 14;} //for frequency >=1kHz, 14 samples for each cycle

Step 5: Full Code



else if (freq>499) {preset = 84; samples = 64;} //for 500<=frequency<1000Hz, 64 samples for each cycle else if (freq>99) {preset = 42; samples = 128;} //for 100Hz<=frequency<500Hz, 128 samples/cycleelse {preset = 21; samples = 256;}; //for frequency<100hz, 256 samples for each cycleinterval = 42000000/(freq*samples); t = 0; TC_SetRC(TC2, 1, interval); } }

Step 5: Full Code



void loop() {checkFreq(); delay(100); }void TC7_Handler(void){ TC_GetStatus(TC2,1);t = t%samples; //use t%samples to avoild overflow of t phaseAInc = (preset*t)%5376; //use %5376 to avoid array index overflowphaseBInc = (phaseAInc+1792)%5376;phaseCInc = (phaseAInc+3584)%5376;

Step 5: Full Code



p_A = sin768[phaseAInc]<<1; //refer to PIOC: PC1 to PC8, corresponding Arduino Due pin: pin 33-40, hence shift left for 1 digitp_B = sin768[phaseBInc]<<12; //refer to PIOC: PC12 to PC19, corresponding Arduino Due pin: pin 51-44, hence shift left 12 digitp_C = sin768[phaseCInc]; //phase C output employe PIOC: PC21, PC22, PC23, PC24, PC25,PC26, PC28 and PC29, corresponding Arduino Due pin: digital pin: 9,8,7,6,5,4,3,10, respectively

Step 5: Full Code



p_C2 = (p_C&B11000000)<<22; //this generates PC28 and PC29p_C3 = (p_C&B00111111)<<21; //this generates PC21-PC26 //Serial.println(p_C3,BIN); p_C = p_C2|p_C3; //this generates parallel output of phase Cp_A = p_A|p_B|p_C; //32 bit output = phase A (8bit)|phase B|phase C //Serial.println(p_A>>21,BIN); //PIOC->PIO_ODSR = 0x37E00000;PIOC->PIO_ODSR = p_A; //output register =p_A t++; }

Step 5: Full Code


THANK YOU


Sine Data Generation Using Arduino Due

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