char arrays and indexing -SOLVED-

Other Hardware Audio
1

hi again!

i'm trying to make a lfo with pushbutton to choose the wave form, so i make some tables, store them on flash, and output it via pwm on timer 2, all fine until here if i call the table directly but now i want to add the button (for testing i just point the index to '0'), so i put an array of char (char*) for indexing the tables and i have only garbage at pwm output
i checked the option of the array by putting a serialprint and it says the 'correct' name of the string, but for some reason the function to assign the table in memory don't works
any help will be appreciated :slight_smile:

here is the code:

#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <pins_arduino.h>

//tabla seno para lfo, un ciclo
PROGMEM prog_uchar sine[] = {
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124};

PROGMEM prog_uchar squa[] = {
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};




//funciones clear bit y set bit
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

//variables para lfo
int lfo_speed;
boolean lfo_rotate;
const int lfo_rotate_pin=2;
int lfo_wave_num=0;
char* lfo_wave[]= {"sine", "squa"};

// variables en la interrupcion 2 (lfo + velocity)
volatile byte icnt;              // var inside interrupt
volatile byte icnt1;             // var inside interrupt
volatile byte c4ms;              // counter incremented all 4ms
volatile unsigned long phaccu;   // pahse accumulator
volatile unsigned long tword_lfo;  // dds tuning word m

void setup() {


  pinMode(11,OUTPUT);      // pin11= PWM del LFO - timer 2 - OC2A
  pinMode(3, OUTPUT);	   // pin3=  PWM Velocity - timer 2 - OC2B
 
  cli();


  Setup_timer2();
		
  sbi (TIMSK2,TOIE2);           //habilita la interrupcion del timer 2

  sei();

}

void loop () {

if (c4ms > 10) {                 // lee cada 10ms

    
    c4ms=0;
    lfo_speed=analogRead(2);      // lee el potenciometro conectado en 2 LFO_Speed
    tword_lfo=50000*lfo_speed+1000;           
  }

}

void Setup_timer2() {

  // Timer2 Clock Prescaler to : 1
  sbi (TCCR2B, CS20);
  cbi (TCCR2B, CS21);
  cbi (TCCR2B, CS22);

  // Timer2 PWM Mode set to Phase Correct PWM
  cbi (TCCR2A, COM2A0);  // clear Compare Match
  sbi (TCCR2A, COM2B1);
  sbi (TCCR2A, COM2A1);

  sbi (TCCR2A, WGM20);  // Mode 1  / Phase Correct PWM
  cbi (TCCR2A, WGM21);
  cbi (TCCR2B, WGM22);
}

ISR(TIMER2_OVF_vect) {

  phaccu=phaccu+tword_lfo; // soft DDS, phase accu with 32 bits
  icnt=phaccu >> 24;     // use upper 8 bits for phase accu as frequency information
  // read value fron ROM sine table and send to PWM 

 // OCR2A=pgm_read_byte_near(sine + icnt); // pin 11 lfo
  OCR2B=pgm_read_byte_near(lfo_wave[lfo_wave_num] + icnt); // pin 3 velocity

  if (icnt1++ == 125) {  // increment variable c4ms all 4 milliseconds
    c4ms++;
    icnt1=0;
  }   
     

}
2

Your table contains character strings with the NAMES of the two tables, not a reference to the table itself.

I think you want something like:

prog_uchar* lfo_wave[]= {sine, squa};

3

One way:

//
// Illustration of multiple function lookup tables (arrays) in Program Memory
//
//  davekw7x
//
#include <avr/pgmspace.h>

PROGMEM const prog_uchar f1[256] =
    //Put 256 values for the first function lookup table here
    { 1, 2, 3, 4, 5, 6, /*...*/};

PROGMEM const prog_uchar f2[256] =
    //Put 256 values for the second function lookup table here
    {101, 102, 103, 104, 105, 106/*...*/};

// As many as you want


//
// Table of pointers.  Entries are the addresses of the first elements of the function arrays
//
PROGMEM const prog_uchar *functionTables[] = {f1, f2};

//
//If you want names, define one for each function
//
PROGMEM const prog_char name1[] = "Potrzebie";
PROGMEM const prog_char name2[] = "Zaphod Beeblebrox";


//
// Table of pointers.  Entries are the addresses of the first chars of the name strings
//
PROGMEM const prog_char *functionNames[] = {name1, name2};


void setup()
{
    Serial.begin(9600);
    for (int functionNumber = 0; functionNumber < 2; functionNumber++) {

        char nameBuffer[80] = {0}; // Must be large enough to hold longest name (+ 1 char for terminating zero)

        // Read pointer from table of pointers
        prog_char *namePointer = (prog_char *)pgm_read_word(&functionNames[functionNumber]);
        // Could write it like this:
        //prog_char *namePointer = (prog_char *)pgm_read_word(functionNames + functionNumber);
        
        // Copy the name from the name table to the buffer for printing.
        strncpy_P(nameBuffer, (char *)namePointer, sizeof(nameBuffer)-1);
        Serial.print("Function number ");Serial.print(functionNumber);Serial.print(": Name is '");
        Serial.print(nameBuffer);Serial.println("'");
        for (int icnt = 0; icnt < 6; icnt++) {

            // Read pointer from table of pointers
            prog_uchar *functionPointer = (prog_uchar *)pgm_read_word(&functionTables[functionNumber]);
            // Could write it like this:
            //prog_uchar *functionPointer = (prog_uchar *)pgm_read_word(functionTables+functionNumber);
            
            // Read byte from the table
            byte x = pgm_read_byte(&functionPointer[icnt]);
            //Could write it like this:
            //byte x = pgm_read_byte(functionPointer+icnt);

            Serial.print("  ");Serial.print(icnt);Serial.print(": ");Serial.println(x,DEC);
        }
        Serial.println();
    }
}

void loop(){}

Output:

[color=blue]Function number 0: Name is 'Potrzebie'
  0: 1
  1: 2
  2: 3
  3: 4
  4: 5
  5: 6

Function number 1: Name is 'Zaphod Beeblebrox'
  0: 101
  1: 102
  2: 103
  3: 104
  4: 105
  5: 106[/color]

Regards,

Dave

4

thanks for reply! i will try as soon as i can do :roll_eyes:

5

yes! it works!

thanks Dave for the hint. here is the working code (far to be complete, but get closing):

#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <pins_arduino.h>

//tabla seno para lfo, un ciclo
PROGMEM const prog_uchar seno[] = {
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124};

PROGMEM const prog_uchar squa[] = {
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,
  250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,250,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

PROGMEM const prog_uchar *functionTables[] = {seno, squa};


//funciones clear bit y set bit
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

//variables para lfo
int lfo_speed;
boolean lfo_rotate;
const int lfo_rotate_pin=2;
int lfo_wave_num=1;


// variables en la interrupcion 2 (lfo + velocity)
volatile byte icnt;              // var inside interrupt
volatile byte icnt1;             // var inside interrupt
volatile byte c4ms;              // counter incremented all 4ms
volatile unsigned long phaccu;   // pahse accumulator
volatile unsigned long tword_lfo;  // dds tuning word m

void setup() {


  pinMode(11,OUTPUT);      // pin11= PWM del LFO - timer 2 - OC2A
  pinMode(3, OUTPUT);	   // pin3=  PWM Velocity - timer 2 - OC2B
 
  cli();


  Setup_timer2();
		
  sbi (TIMSK2,TOIE2);           //habilita la interrupcion del timer 2

  sei();

}

void loop () {

if (c4ms > 10) {                 // lee cada 10ms

    
    c4ms=0;
    lfo_speed=analogRead(2);      // lee el potenciometro conectado en 2 LFO_Speed
    tword_lfo=50000*lfo_speed+1000;           
  }
  
  
 
    
  
}

void Setup_timer2() {

  // Timer2 Clock Prescaler to : 1
  sbi (TCCR2B, CS20);
  cbi (TCCR2B, CS21);
  cbi (TCCR2B, CS22);

  // Timer2 PWM Mode set to Phase Correct PWM
  cbi (TCCR2A, COM2A0);  // clear Compare Match
  sbi (TCCR2A, COM2B1);
  sbi (TCCR2A, COM2A1);

  sbi (TCCR2A, WGM20);  // Mode 1  / Phase Correct PWM
  cbi (TCCR2A, WGM21);
  cbi (TCCR2B, WGM22);
}

ISR(TIMER2_OVF_vect) {

  phaccu=phaccu+tword_lfo; // soft DDS, phase accu with 32 bits
  icnt=phaccu >> 24;     // use upper 8 bits for phase accu as frequency information
  
  // read value fron ROM sine table and send to PWM 
  prog_uchar *functionPointer = (prog_uchar *)pgm_read_word(&functionTables[lfo_wave_num]);
  OCR2A=pgm_read_byte(&functionPointer[icnt]); // pin 11 lfo

  if (icnt1++ == 125) {  // increment variable c4ms all 4 milliseconds
    c4ms++;
    icnt1=0;
  }   
     

}