Bitshift and write to port D

dannysprogis · October 23, 2021, 10:03am

hi guys,

I would like some help to create a repeating pattern with 6 leds.

I have Six LEDs connected in a ring to pins 4,5,6,7,8,9 of a nano.

I would like to set up a pattern in binary and write it to the pins and cycle it through endlessly.

I need the function to work without using delay and I would like to do something smart with bit shift and operations but I am struggling to get started and understand how I mask the upper 2 bits as I am not using them as output pins.

This is the first pattern I want to achieve

000001
000010
000100
001000
010000
100000

and here is the code I have so far:




#define REDLED_1 8
#define REDLED_2 7
#define REDLED_3 6
#define REDLED_4 5
#define REDLED_5 4
#define REDLED_6 9

#define ON_time 30
#define OFF_time 5




unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)

int Pattern1 = B000000001;

byte    pins[2, 3, 4, 5, 6, 7, 8, 9];
byte*   p = pins;


void setup() {

  pinMode(REDLED_1, OUTPUT);
  pinMode(REDLED_2, OUTPUT);
  pinMode(REDLED_3, OUTPUT);
  pinMode(REDLED_4, OUTPUT);
  pinMode(REDLED_5, OUTPUT);
  pinMode(REDLED_6, OUTPUT);
}


void loop() {
unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    ENGINE_SPIN();
  }
}

void ENGINE_SPIN(){
  for (pins[i]=0;i<=6;i++){
    digitalWrite(pins[i], Pattern1 && B00111111); // not sure how to get the correct bit from Pattern1
    //bitshift >> // not sure how to shift the bits on pattern1 and make it roll over from MSB to LSB again?
    //
    }  
  }

Any help would be greatly appreciated.

anon73444976 · October 23, 2021, 10:12am

You can add a "=" if you wish

I'm not clear why you don't use the pins array here

dannysprogis · October 23, 2021, 10:28am

REDLED_X is just remnants of test code to make sure the leds are wired correctly.




//#define REDLED_1 8
//#define REDLED_2 7
//#define REDLED_3 6
//#define REDLED_4 5
//#define REDLED_5 4
//#define REDLED_6 9

#define ON_time 30
#define OFF_time 5


unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)

int Pattern1 = B000000001;

byte    pins[6] = {2, 3, 4, 5, 6, 7, 8, 9};
byte*   p = pins;


void setup() {

  pinMode(pins[1], OUTPUT);
  pinMode(pins[2], OUTPUT);
  pinMode(pins[3], OUTPUT);
  pinMode(pins[4], OUTPUT);
  pinMode(pins[5], OUTPUT);
  pinMode(pins[6], OUTPUT);
}


void loop() {
unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    ENGINE_SPIN();
  }
}

void ENGINE_SPIN(){
  for (pins[i]=0;i<=6;i++){
    digitalWrite(pins[i], Pattern1 && B00111111); // not sure how to get the correct bit from Pattern1
    //bitshift >> // not sure how to shift the bits on pattern1 and make it roll over from MSB to LSB again?
    //
    }  
  }

anon73444976 · October 23, 2021, 10:29am

Double oops

dannysprogis · October 23, 2021, 10:31am

thanks for the help...

anon73444976 · October 23, 2021, 10:32am

"Pattern1" is non-zero, therefore true.
B00111111` is clearly non-zero and so also true.

I think you meant & not &&.

But they're both constants, so I'm not sure why you'd want that.

dannysprogis · October 23, 2021, 10:42am

I figure I need to mask out the upper 2 bits so I am only affecting the 6 outputs I want to control. so yes I have made a mistake and need to AND them

and Pattern 1 is what I want to bit shift left or right to cycle the pattern.

anon73444976 · October 23, 2021, 10:43am

Have you fixed the array?

dannysprogis · October 23, 2021, 10:44am

yes I have fixed the array thanks.




//#define REDLED_1 8
//#define REDLED_2 7
//#define REDLED_3 6
//#define REDLED_4 5
//#define REDLED_5 4
//#define REDLED_6 9

#define ON_time 30
#define OFF_time 5


unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)

int Pattern1 = B000000001;

byte    pins[6] = {4, 5, 6, 7, 8, 9};
byte*   p = pins;


void setup() {

  pinMode(pins[1], OUTPUT);
  pinMode(pins[2], OUTPUT);
  pinMode(pins[3], OUTPUT);
  pinMode(pins[4], OUTPUT);
  pinMode(pins[5], OUTPUT);
  pinMode(pins[6], OUTPUT);
}


void loop() {
unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    ENGINE_SPIN();
  }
}

void ENGINE_SPIN(){
  for (pins[i]=0;i<=6;i++){
    digitalWrite(pins[i], Pattern1 & B00111111); // not sure how to get the correct bit from Pattern1
    //bitshift >> // not sure how to shift the bits on pattern1 and make it roll over from MSB to LSB again?
    //
    }  
  }

anon73444976 · October 23, 2021, 10:44am

So, that's a "no" then.

Can you talk us through what you think ENGINE_SPIN should do, please?
There seem to be a ton of misunderstanding in there.

(All caps are usually reserved for macros)

dannysprogis · October 23, 2021, 10:55am

What have I done wrong with the pins array?

I have renamed ENGINE_SPIN to Cycle_6_Leds but i want it to start with the contents of Pattern1 and cycle outputs every interval.

000001
000010
000100
001000
010000
100000

dannysprogis · October 23, 2021, 10:55am




//#define REDLED_1 8
//#define REDLED_2 7
//#define REDLED_3 6
//#define REDLED_4 5
//#define REDLED_5 4
//#define REDLED_6 9

#define ON_time 30
#define OFF_time 5


unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)

int Pattern1 = B000000001;

byte    pins[6] = {4, 5, 6, 7, 8, 9};
byte*   p = pins;


void setup() {

  pinMode(pins[0], OUTPUT);
  pinMode(pins[1], OUTPUT);
  pinMode(pins[2], OUTPUT);
  pinMode(pins[3], OUTPUT);
  pinMode(pins[4], OUTPUT);
  pinMode(pins[5], OUTPUT);
}


void loop() {
unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    Cycle_6_Leds();
  }
}

void Cycle_6_Leds(){
  for (pins[i]=0;i<=6;i++){
    digitalWrite(pins[i], Pattern1 & B00111111); // not sure how to get the correct bit from Pattern1
    //bitshift >> // not sure how to shift the bits on pattern1 and make it roll over from MSB to LSB again?
    //
    }  
  }

anon73444976 · October 23, 2021, 10:57am

Changing the name doesn't decrease the amount of misunderstanding.
Please talk us through it

  pinMode(pins[0], OUTPUT);

A for loop here would reduce the amount of duplicated code

dannysprogis · October 23, 2021, 10:58am

Telling people they have made mistakes and not explaining doesn't help either.

anon73444976 · October 23, 2021, 11:00am

It gives you a chance to review your code and ask questions about what you think the problem might be, or fix the problem yourself without feeling patronised or dumb.

dannysprogis · October 23, 2021, 11:06am

No, the way you have written everything is patronising.

Patronising examples are "clearly" and "that's a no then" and "have you fixed"

Examples of helpful non patronising sentences are "there is a problem with your array.. you should look at... to fix it"

anon73444976 · October 23, 2021, 11:16am

OK, I can see you'd rather have a meta-argument than fix your code (I still can't see where PORTD comes into the problem), so I'll leave you to get on with it.

Good luck.

dannysprogis · October 23, 2021, 11:17am

Dude you are the one being derogatory and unhelpful.

dannysprogis · October 23, 2021, 11:19am

meanwhile I have been trying to fix my code and write psudocode to better explain what i am trying to do.




//#define REDLED_1 8
//#define REDLED_2 7
//#define REDLED_3 6
//#define REDLED_4 5
//#define REDLED_5 4
//#define REDLED_6 9

#define ON_time 30
#define OFF_time 5


unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)

int Pattern1 = B000000001;

byte    pins[6] = {4, 5, 6, 7, 8, 9};
byte*   p = pins;


void setup() {

  pinMode(pins[0], OUTPUT);
  pinMode(pins[1], OUTPUT);
  pinMode(pins[2], OUTPUT);
  pinMode(pins[3], OUTPUT);
  pinMode(pins[4], OUTPUT);
  pinMode(pins[5], OUTPUT);
}


void loop() {
unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    Cycle_6_Leds();
  }
}

void Cycle_6_Leds(){
 //turn on LED at pins[0] //000001   - pattern1 000001 - pattern2 0000101
 // bit shift left 
 //turn on LED at pins[1] //000010
 // bit shift left 
 //turn on LED at pins[2] //000100
 // bit shift left 
 //turn on LED at pins[3] //001000
 // bit shift left 
 //turn on LED at pins[4] //010000
 // bit shift left 
 //turn on LED at pins[5] //100000
 // overflow bit and start at pins[0] again 
    }  
  }

PaulRB · October 23, 2021, 12:53pm

void Cycle_6_Leds(){
  static byte led = 0;
  digitalWrite(pins[led], LOW);
  if (++led >= sizeof(pins)/sizeof(pins[0])) led = 0;
  digitalWrite(pins[led], HIGH);
}

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Bitshift and write to port D

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