Simple Sequential : Led + Breadboard

[EdiFirst 0]

Hello, Guys!

 

 So, as some already know I 'm  a noob with embedded system and I really I'm  liking of the series MSP430 by TI.

 

I am trying make this code work, but so far  I did not succeed, What  I want is a simple led sequential on the breadboard, the breadboard will be 9 Leds, being 6 on Port 1, e just 3 in the Port 2 for now.

That code work but not syncronized,  I'd want which when end the first "array" of the leds, starts the seconds "arrays" of the leds (port 2, 3 leds), I would like to use someone like struct in C but I don't have know enough yet, the code:

 

 #include <msp430G2553.h>


  void Delay(void);
  void sequencial(void);
  char led1[7] = {BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6};
  char led2[3] = {BIT0, BIT1, BIT2};
  volatile int i = 0;
  volatile int f = 0;
 
  int main(void) {
    
  WDTCTL = WDTPW | WDTHOLD;
  P1DIR = 0xff;
  P2DIR = 0xff;
 
 
        for (; {
          sequencial();
              }
  }
    
    void Delay(void) {
        unsigned int dly = 30000;
        while(--dly); {
            
        }
        }
      void sequencial(void){
        i++;
          Delay();
        P1OUT = led1;
       if(i==7) i=0;
           
         P1OUT |= 0x00;
            f++;
              Delay();
             P2OUT = led2[f];
              if(f==3) f=0;
              
             P2OUT |= 0x00;
      }
   

 

The outpouts are working separately not synchronized, How do I make this? Thanks!

[EdiFirst 0]

Someone please?

[roadrunner84 466]

void sequencial(void){
  i++;
  Delay();
  if (i < 7)
  {
    P1OUT = led1[i];
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = led2[i - 7];
  }
  if (i == 7 + 3) i = 0;
}

Like this?

[EdiFirst 0]

 

void sequencial(void){
  i++;
  Delay();
  if (i < 7)
  {
    P1OUT = led1[i];
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = led2[i - 7];
  }
  if (i == 7 + 3) i = 0;
}

Like this?

Thank you again Road!

I did not tester yet, but surely will go work.Is amazing as you solve fast the stuffs, i was thinking someone stuff like

this,but Iam very slowly..I was caught in the loop for.

How we can solve that using struct and bitwise/bit operation?

[roadrunner84 466]

What do you mean? You want to use bitwise operations instead of the arrays you're currently using? How do you intend that? Do you want to have a similar function (a moving light) but without using the array?

 

I do suggest moving the Delay(); call to the for loop, so in the future you can call sequential from a timer interrupt instead of using a delay. This is good practice for low power operations. As such, the sequential function would not be blocking anymore and can be put in/called from an ISR.

[EdiFirst 0]

What do you mean? You want to use bitwise operations instead of the arrays you're currently using? How do you intend that? Do you want to have a similar function (a moving light) but without using the array?

 

I do suggest moving the Delay(); call to the for loop, so in the future you can call sequential from a timer interrupt instead of using a delay. This is good practice for low power operations. As such, the sequential function would not be blocking anymore and can be put in/called from an ISR.

So, Roadrunner now I arrived at home, I tested the code and I don't no why de 1

[roadrunner84 466]

Ah, I see. You should move the i++ to after the LED output but before the if() i=0;

Try to follow the flow of the program.

If i is 0, it will first be incremented and then used to look up the LED.

If i is 9, it will first be incremented and then used to look up the LED... hang on, this means that I will look up location 10 - 7, which is 3. led2[3] only has indexes 0, 1 and 2. So this means that after led2[2] is written, I will write an illegal memory value to P2OUT!

So by moving i++ down, I both enable using led1[0] and disable using the illegal memory location led2[3].

void sequencial(void){
  // remove i++ here
  Delay();
  if (i < 7)
  {
    P1OUT = led1[i];
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = led2[i - 7];
  }
  i++; // add i++ here
  if (i == 7 + 3) i = 0;
}

Now, I'm still not really sure what you want to do with the struct. But I assume you want to use bitwise operators to manipulate the value of your LED output.

I will be using a trick here that only works fine wit the value line MSP430. I use the property that it has two and only two ports, which both are half the size of my word size. The ports P1 and P2 are both 8 bits wide, while my word size (unsigned short) is 16 bits wide; twice as wide.

As a result I can use a single number to address both ports. This is not a very clean trick and should not be considered good practice.

unsigned short i;

void sequencial(void){
  i <<= 1; // move i one bit to the left, identical to i = i << 1; also identical to i += i; and i = i + i;
  if (!(i & 0x07FF)) i = 1; // since we only use 3 bits of P2, if none of the lower 8 + 3 = 11 bits is high, reset i to ONE
  if (i & 0xFF)
  {
    P1OUT = i;
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = i >> 8; // use the higher byte of i, done by shifting the value by 8.
  }
  Delay();
}

Note that the MSP430 cpu architecture is designed without a barrel shifter, this means that using a shift operator is expensive if done by any value other than 1. The exceptions are the values 8 and 16, since the first is built in as a byte swap (inside a 16 bit word) and the second a word swap (done in software, takes 3 assignments).

 

Alternatively you could use two separate variables, but it will be a little more difficult:

unsigned char i1, i2;

void sequencial(void){
  i2 <<= 1; // shift counter for P2
  if (i1 & 0x80) i2 |= 1; // and set the lowest bit high if it would be carried from i1
  i1 <<= 1; // sift counter for P2
  if ((i1 == 0) && !(i2 & (BIT1 | BIT2 | BIT3))) // if none of the used 11 bits is high, reset the values
  {
    i1 = 1;
    i2 = 0;
  }
  P1OUT = i1;
  P2OUT = i2;
  Delay();
}

[EdiFirst 0]

Ah, I see. You should move the i++ to after the LED output but before the if() i=0;

Try to follow the flow of the program.

If i is 0, it will first be incremented and then used to look up the LED.

If i is 9, it will first be incremented and then used to look up the LED... hang on, this means that I will look up location 10 - 7, which is 3. led2[3] only has indexes 0, 1 and 2. So this means that after led2[2] is written, I will write an illegal memory value to P2OUT!

So by moving i++ down, I both enable using led1[0] and disable using the illegal memory location led2[3].

 

void sequencial(void){
  // remove i++ here
  Delay();
  if (i < 7)
  {
    P1OUT = led1[i];
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = led2[i - 7];
  }
  i++; // add i++ here
  if (i == 7 + 3) i = 0;
}

Now, I'm still not really sure what you want to do with the struct. But I assume you want to use bitwise operators to manipulate the value of your LED output.

I will be using a trick here that only works fine wit the value line MSP430. I use the property that it has two and only two ports, which both are half the size of my word size. The ports P1 and P2 are both 8 bits wide, while my word size (unsigned short) is 16 bits wide; twice as wide.

As a result I can use a single number to address both ports. This is not a very clean trick and should not be considered good practice.

unsigned short i;

void sequencial(void){
  i <<= 1; // move i one bit to the left, identical to i = i << 1; also identical to i += i; and i = i + i;
  if (!(i & 0x07FF)) i = 1; // since we only use 3 bits of P2, if none of the lower 8 + 3 = 11 bits is high, reset i to ONE
  if (i & 0xFF)
  {
    P1OUT = i;
    P2OUT = 0;
  }
  else
  {
    P1OUT = 0;
    P2OUT = i >> 8; // use the higher byte of i, done by shifting the value by 8.
  }
  Delay();
}

Note that the MSP430 cpu architecture is designed without a barrel shifter, this means that using a shift operator is expensive if done by any value other than 1. The exceptions are the values 8 and 16, since the first is built in as a byte swap (inside a 16 bit word) and the second a word swap (done in software, takes 3 assignments).

 

Alternatively you could use two separate variables, but it will be a little more difficult:

unsigned char i1, i2;

void sequencial(void){
  i2 <<= 1; // shift counter for P2
  if (i1 & 0x80) i2 |= 1; // and set the lowest bit high if it would be carried from i1
  i1 <<= 1; // sift counter for P2
  if ((i1 == 0) && !(i2 & (BIT1 | BIT2 | BIT3))) // if none of the used 11 bits is high, reset the values
  {
    i1 = 1;
    i2 = 0;
  }
  P1OUT = i1;
  P2OUT = i2;
  Delay();
}

Very clearely Roadrunne!

I did solved the "bug" making the i= -1

About your another approaches,was this which I was looking for really,anothers way to solve the issue.

After I'll try make with interrupt and push bottons for change the behavior of the move.:-)