Question with writing to Port x

Using Arduino Programming Questions
1

Hello and thank you for your time,

Quick question, I have this code from a LCD screen I am using:

void comm_out(unsigned char c)
{
  digitalWrite(RS, LOW);      //A0 = L = command
  PORTA = c;
  digitalWrite(WR, LOW);
  digitalWrite(WR, HIGH);
}

In this code, c is passed as a hex in the (0xff) form.

Now I am trying to transfer this code from a mega 2560 to an atmega 328P. I have not experimented with this yet, but would writing to port d have the same effect? Likewise, I may be using the RX and TX pins on the mega 328. These pins are on port D; see: https://www.arduino.cc/en/Hacking/PinMapping168. Is there a conventional way of writing to 8 digital pins? I would assume a string of if statements with minus 128, 64, 32, etc... would work. I am just asking if there is a more efficient approach.

Thanks again :slight_smile: ,

Joseph Samo

2

Is there a conventional way of writing to 8 digital pins?

On which port on which Arduino?

3

You need to be aware that you should not change all the pins on ANY of the ports on an Uno or on some of the ports on a Mega.

...R