ISR (SPI_STC_vect) firing too many times - 8bit LabView boolean array along MOSI

in labview, i'm testing spi 8-bit signal loop, pretty identical to:

http://www.ni.com/example/9398/en/

the labview program acts master...the arduino mega slave

when use logic analyzer @ points right before signal reaches mega spi lines, looks fine , dandy (ss, sck, mosi produce correct results.)

however, more coding isr routine incorrectly handle capturing of byte.

if send number "11" labview (which gets converted lsb boolean array), isr (spi_stc_vect) in arduino program fires off couple hundred times.

code: [select]



volatile boolean process_it;
char buff[10];
volatile byte spot;

// here's code setup:

void setup() {
  serial.begin(115200);
  serial.println("begin transmissions, rotundra!");
  pinmode(miso, output);
  spcr |= bit(spe);
  spcr |= bit(spie);
  //spi.attachinterrupt();
}

// here's loop:

void loop() {
  valuesspi();
  delay(20);
}

// here's 'valuesspi()' , 'isr(spi_stc_vect)' functions:

void valuesspi() {
  if (process_it) {
    buff[spot] = 0;
    spot = 0;
    process_it = false;
}

isr (spi_stc_vect) {
  byte b = spdr;
  serial.println(b);
  if (spot < 11) {buff[spot++] = b;}
  else {process_it = true;}
}



i receive ton of serial prints byte (i verify analyzer 8 bits sent, yet printing 'b' doesn't verify that.)  i want know how capture 1 byte labview, process correctly, , print it.  i did not use reverse array in labview, @ best should getting larger results 256 (just confirm i'm not reversing lsb order.)  but not occurring.

the byte should have bits containing number values ranging 1-20.

i new this, please go detail if have to.


i attached .txt show 'serial.println(b)' output (i apologize length.)

don't put serial.print()s isr. in loop() after isr has completed.

...r

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