Controlling arduino digital outputs through serial

Projects Programming
1

Hi gyus I wrote this code in order to control the arduinos digital outputs by sending it a string with 54 1s or 0s, for example 00100000000000000000000000000000000000000000 is only turn digital output 3 HIGH, but havent found why it isnt working, really hope you can help me see what im missing!

int io[52]; //save each pin state here
int d = 0;
void setup() {
  Serial.begin(9600);
  for (int i = 3; i <= 52; i++)
  {
    pinMode(i, OUTPUT);
    digitalWrite(i, 0);  //initiate pins off
  }
}
void loop()
{
  if (Serial.available() > 0)
  {
    io[d] = Serial.read(); // save all 252 incoming values into this array
    Serial.print(io[d]);
    d++;
    if (d == 52) //when all values are received, start processing
    {
      d = 0;
      Serial.write("Applying");
      for (int i = 3; i < 52; i++)
      {
          digitalWrite(i, io[i]);        
      }
    }
  }
}
2

I think you want to make the array 54 bytes, and then start d at 2.
digitalWrite of 0, 1 would not be used to avoid interfering with Serial.

for (int i = 3; i <= 52; i++)

Shouldn't this be 2 to 53?

Same here
for (int i = 3; i < 52; i++)

3

How do you know it isn't working? What actually happens?

What Arduino are you using?

Are you sure that enough chars are being sent to trigger the "if (d == 52)"

Are you sending chars (i.e. the character 1 = byte value 49) or bytes with values of 1 and 0?

...R

4

I have a RGB led connected to pins 12 and 13 to check function, but it never turns on.
Im using an Arduino Due
Yes, Im sending enough chars (value 1 =49) so the arduino sends me the "applying"message when it should start opening the outputs, but they arent.

Crossroads, how do I make the array 54 bytes?

5

Ok I think I got it, it isnt working because it is considering ASCII decimal value (49 for 1, 48 for 0), not the char, how do I convert this value when arriving from the serial read?

6

Subtract '0'

7

change
int io[52]; //save each pin state here
to
byte io[54]; //save each pin state here

doesn't need to be an int

Could also compress the data - just send 7 bytes
byte io[7];
byte byte 0 representing D0-D7.
byte 1 D8-D15,
byte 2 D16-D23, etc.
If you can further map the bytes to Ports, makes it really easy!
byte 0 = PORTA,
byte 1 = PORTB, etc. then

if (Serial.availabe()>6){ // 7 bytes received
PORTA = Serial.read();
PORTB = Serial.read();
PORTC = Serial.read();
PORTD = Serial.read();
PORTE = Serial.read();
PORTF = Serial.read();
PORTG = Serial.read();
}
Won't be quite that simple, I think a couple ports are only partly used, and have to not mess up the serial port, but it's way less data to mess with.

8

Steinhoff:
Ok I think I got it, it isnt working because it is considering ASCII decimal value (49 for 1, 48 for 0), not the char, how do I convert this value when arriving from the serial read?

How do you convert 49 to 1 and 48 to 0?

Subtraction...

9

Ok I think I got it, it isnt working because it is considering ASCII decimal value (49 for 1, 48 for 0), not the char, how do I convert this value when arriving from the serial read?

Maybe something like below.

if (Serial.available()>0){
Serial.print (Serial.read() - 48);
}
10

Subtract '0'

Or, just use

if(io[d] == '0')
// off
else if(io[d] == '1')
// on
11

Ok thank you all, I did what you said and also had to add one piece of code to tell the arduino when to start receiving the io[] array strings, because when you open the serial port it sends some data, which contaminated the io[] array. Now it works perfectly.