Arduino Due direct Port Manipulation

Official Hardware Mega Due
1

Hello Guys,

i want to reproduce the Signal in the Attachement on only 1 Pin on the Arduino Due.

Here are the Signal specifications:

-> at all the Signal consists out of 19 blocks â 16Bit
-> the first 2 Blocks are every time the same "AAAB" and "2000" the 3rd Block should be variable later
and the last 16 blocks are every time the same "0000"
-> the coding of the Signal in the attachment is, that 1 is a falling edge and 0 is a rising edge
-> between every Bit there is a pause â 1us....(so 1us is the sampling rate)..Signal = 1 Mhz

Can u help me to realize that in a Code for my arduino ?:confused:

I did something before, to get 4 different Signals â 16Bit on the same Pin by push a Button

#define NOP __asm__ __volatile__ ("nop\n\t");
#define PAUSE NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP
// 1 NOP Befehl entspricht 12ns (1/84MHz)
void setup() {
pinMode(5, OUTPUT); 
Serial.begin(115200);  
}
void loop() {
/*
on pin 5: 
  Signal 1: 1010 1010 1100 1100  
          Signal 2: 1110 1110 1010 1010
          Signal 3: 1010 0110 0110 1010
          Signal 4: 1101 1101 0011 0010
*/
if(Serial.available()>0){ 

byte input = Serial.read();
 
Pio *p = digitalPinToPort(7); // Port.C

uint32_t s5 = digitalPinToBitMask(5);
uint32_t c5 = digitalPinToBitMask(5);
    
switch (input){
  case '1':
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE            
  p->PIO_CODR = c5; PAUSE 
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE 
  p->PIO_CODR = c5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE 
  p->PIO_CODR = c5; PAUSE
  break;
  case '2':
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE   
  p->PIO_CODR = c5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE  
  break;

  case '3':
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE 
  p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE 
  p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE 
  p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE 
  break;
  case '4':
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE 
  p->PIO_SODR = s5; PAUSE
  p->PIO_SODR = s5; PAUSE p->PIO_SODR = s5; PAUSE p->PIO_CODR = c5; PAUSE 
  p->PIO_SODR = s5; PAUSE
  p->PIO_CODR = c5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE p->PIO_CODR = c5; PAUSE p->PIO_SODR = s5; PAUSE 
  p->PIO_CODR = c5; PAUSE 
  break; 
  } 
 }
}

Can I use it maybe for this Task by rewirting ?
Or maybe u have a new Solution for it :slight_smile:
Would be fine !

Best regards and thank u !

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2

There's probably a name for this particular protocol. Once you discover the name you can see if the Due (or other suitable chip) has a hardware mode to produce this protocol.

If I was doing it and there wasn't a name for the protocol, I'l be trying to make the SPI module perform the function. There's a lot of capability in the USARTs on the Due which isn't normally used by Arduino programs.

3

ah okay....i dont did something with SPI or UARTS before with the due..

Do u have an example code or something like that for my Problem ?

4

// 1 NOP Befehl entspricht 12ns (1/84MHz)

It is not that easy, yes, 1 NOP corresponds to 1 clock tick, but 8 nop operations take 9 Arduino Due clock cycles.

Hemann.

5

It is not that easy, yes, 1 NOP corresponds to 1 clock tick, but 8 nop operations take 9 Arduino Due clock cycles.

ah okay, thats new for me...

and how many nop operations i Need for 500ns break ?

i calculated 42, but thats wrong now :smiley:

is it even 1 more after 8 operations ? so 16 nop = 18 clock cycles ?