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Change multiple values in a boolean array?

l1t7l3ph0o7

I can't seem to figure this one out,

the scenario is, I have two shift registers connected to my arduino and 16 leds connected to them.

I have a boolean array of 16, then I wrote a function that writes the array to the shift registers. Thats what the writereg(); is

 

I can do neat things like:

for (int i = 1; i<16; i++){

registers[i] = high

}

writereg();

and one led will light up one after the other

 

But is there a way to light up specific multiple leds without a for loop in a single line of code?

The only thing I can think to do is:

registers[1] = HIGH;

registers[4] = HIGH;

registers[10] = HIGH;

registers[16] = HIGH;

writereg();

it would be neat if I could do something like this:

registers[1,4,10,16] = HIGH;

writereg();

anyone know, just curious if there is a less caveman approach to what I'm doing

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  • 0

    The answer to your question is quite simple

     

    Direct port manipulation

     

    The ATMEGA328 has 3 sets of ports, A, B and C, not all pins of each port are available but it is basically laid out like this

    • B (digital pin 8 to 13)
    • C (analog input pins)
    • D (digital pins 0 to 7)

    there are 3 registers per port, the DDR register (Data Direction Register), the the Port Register (Sets the pin high or Low if it is an output) and the PIN register that reads the port

     

    there are some pins that you cant use, for instance Port B pin 6 and 7 are used by the XTAL to not available to you

     

    those ports and pins you can use are directly controllable like this

     

    DDRD = B11111110; // sets Arduino pins 1 to 7 as outputs, pin 0 as input, where with the old method it took 7 commands, this takes 1

    DDRD = DDRD | B11111100; // this is safer as it sets pins 2 to 7 as outputs, this effectively reads the port, or's it with the mask and sends it out again to set the direction

    // without changing the value of pins 0 & 1, which are RX & TX and if you want to keep using serial,Read or serial.Write, leave these pins alone

     

    now you can control the port set in one command also as follows

    PORTD = B10101000; // sets digital pins 7,5,3 HIGH, you can do the same with the other ports too

     

    you can of course do way more than this with direct port manipulation but this should et you started, mastering boolean algebra will help here to make very efficient code

     

    for a fuller description of this see this link on the Arduino web site Arduino - PortManipulation

     

    Hope this helps, if you need more help, please ask

     

    Peter

  • 0 in reply to Robert Peter Oakes

    I'm not sure you understood my question, Or maybe I'm just am having trouble understanding your answer.

    It seems to me that port manipulation is useful for controlling the pins on my arduino, I'm attempting to control pins on two 74hc595 shift registers attached to my arduino.

    am I missing something here?

  • 0 in reply to l1t7l3ph0o7

    Yup, you nailed it, good advice but for the wrong IO, sorry about that, looks like BOB has it nailed though so now you have two ways depending on your hardware setup

     

    Good luck

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