2

You can try the code on your arduino UNO to better understand what is hapening in serial monitor!

I want to calculate jacobian matrix from rotation matrix!

float jakMATB[3][3] = {
{0, 0, 0},
{0, 0, 0},
{0, 0, 0}
     };
float POKUS = 0;
float k = 0.000001;
float dt = 0.001;
float b = 90 * (PI / 180);
float vnB[3] = {0, 1, 0}, vpB[3] = {0, 1, 1};
float nB[3] = {0, 1, 0};
float nBplus[3] = {0 , 1, 0};
float nBminus[3] = {0, 1, 0};
void setup() {
Serial.begin(9600);
Serial.print("init ok");
cli();//stop interrupts
TCCR1A = 0;// set entire TCCR1A register to 0
TCCR1B = 0;// same for TCCR1B
TCNT1  = 0;//initialize counter value to 0
// set compare match register for 1hz increments
OCR1A = (16000000) / ((1 / dt) * 1024) - 1; // 15624 = (16*10^6) / ((1)*1024) - 1 (must be <65536)
// turn on CTC mode
TCCR1B |= (1 << WGM12);
// Set CS12 and CS10 bits for 1024 prescaler
TCCR1B |= (1 << CS12) | (1 << CS10);
// enable timer compare interrupt
TIMSK1 |= (1 << OCIE1A);
sei();//allow interrupts
}

when I call the function in loop everithing works fine and I get 1 2 1 in serial monitor

 void loop() {
 izracunJAKOB();
 for (int j = 0; j <= 2; j++) {
for (int i = 0; i <= 2; i++) {
  Serial.print(jakMATB[j][i]);
  Serial.print(" ");
}
Serial.println("");
}
}

when I call izracunJAKOB() with timer interupt Serial monitor stops working and doesent event write "init ok"

ISR(TIMER1_COMPA_vect) {
  //izracunJAKOB();
 }
void izracunJAKOB() {
for (int j = 0; j <= 2; j++) {
for (int i = 0; i <= 2; i++) {
  nBplus[j] = nB[j] + k;
  nBminus[j] = nB[j] - k;
  float matricaBplus[3][3] = {
    {cos(b) + nBplus[0]*nBplus[0]*(1 - cos(b)), nBplus[1]*nBplus[0]*(1 - cos(b)) - nBplus[2]*sin(b), nBplus[0]*nBplus[2]*(1 - cos(b)) + nBplus[1]*sin(b)},
    {nBplus[1]*nBplus[0]*(1 - cos(b)) + nBplus[2]*sin(b), cos(b) + nBplus[1]*nBplus[1]*(1 - cos(b)), nBplus[1]*nBplus[2]*(1 - cos(b)) - nBplus[0]*sin(b)},
    {nBplus[0]*nBplus[2]*(1 - cos(b)) - nBplus[1]*sin(b), nBplus[1]*nBplus[2]*(1 - cos(b)) + nBplus[0]*sin(b), nBplus[2]*nBplus[2]*(1 - cos(b)) + cos(b)}
  };
  float matricaBminus[3][3] = {
    {cos(b) + nBminus[0]*nBminus[0]*(1 - cos(b)), nBminus[1]*nBminus[0]*(1 - cos(b)) - nBminus[2]*sin(b), nBminus[0]*nBminus[2]*(1 - cos(b)) + nBminus[1]*sin(b)},
    {nBminus[1]*nBminus[0]*(1 - cos(b)) + nBminus[2]*sin(b), cos(b) + nBminus[1]*nBminus[1]*(1 - cos(b)), nBminus[1]*nBminus[2]*(1 - cos(b)) - nBminus[0]*sin(b)},
    {nBminus[0]*nBminus[2]*(1 - cos(b)) - nBminus[1]*sin(b), nBminus[1]*nBminus[2]*(1 - cos(b)) + nBminus[0]*sin(b), nBminus[2]*nBminus[2]*(1 - cos(b)) + cos(b)}
  };
  jakMATB[i][j] = (matricaBplus[i][j] - matricaBminus[i][j]) / (2 * k);
  nBplus[0] = 0;
  nBplus[1] = 1;
  nBplus[2] = 0;
  nBminus[0] = 0;
  nBminus[1] = 1;
  nBminus[2] = 0;
}
}
}

////////////////////////////// when I comennt out

   nBplus[j] = nB[j] + k;
   nBminus[j] = nB[j] - k;

and

   nBplus[0] = 0;
   nBplus[1] = 1;
   nBplus[2] = 0;
   nBminus[0] = 0;
   nBminus[1] = 1;
   nBminus[2] = 0;

Serial works just fine

when I coment out only matricaBminus and matricaBplus serial works fine

Please help! It surely is a stupid solution!

5
  • 1
    I only get hello world in Serial. Did I get overflow on MCU?
    – boki
    Commented Oct 15, 2020 at 17:29
  • Though that might not be the cause of your problem, do you put the printing of the matrix in loop() into a critical section (with interrupts turned off)? If not, the interrupt might happen in the middle of printing. Please show a complete example sketch for the interrupt version of the code.
    – chrisl
    Commented Oct 15, 2020 at 17:55
  • @chrisl Timer was to fast! When I decreased frequency everithing worked fine.
    – boki
    Commented Oct 15, 2020 at 18:10
  • It generally not advised to use serial inside an interrupt.
    – Gerben
    Commented Oct 15, 2020 at 19:24
  • It is even impossible to use Serial in an interrupt, if you risk to overflow the output buffer. You cannot write more than 63 characters (to normal arduinos) from an ISR. Commented Oct 26, 2020 at 15:26

1 Answer 1

1

Timer was to fast! When I decreased frequency everithing worked fine.

2
  • Increasing the baudrate to something higher that 9600 also helps.
    – Gerben
    Commented Oct 15, 2020 at 19:19
  • 1
    This may seems to solve your problem, however, it is not a best practise for the way you using interrupt. You should read interrupt by Nick Gammon.
    – hcheung
    Commented Oct 16, 2020 at 2:51

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