Trouble with "Serial.println" ?

Projects General Guidance
1

I'm working on a key-pad sort of project (just messing around) and whenever I upload the code and open up the Serial monitor, I get a whole bunch of P's and @ signs. Both the monitor and the arduino are on the same sample speed (9600) and I just have no idea what's going on. It could be because I'm printing a character rather than a number but I'm not sure, please help! Here's my code:

int current;
int pins[]={1,2,3};
int count=3;
void setup()
{
  pinMode(1,OUTPUT);
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  Serial.begin(9600);
}
void loop()
{
  for (current=0;current<count;current++)
  {
    digitalWrite(pins[current],HIGH);
    digitalWrite(pins[current],LOW);
  }
  if (digitalRead(1)==HIGH && digitalRead(4)==HIGH)
  {
    Serial.println("1");
  }
   if (digitalRead(2)==HIGH && digitalRead(4)==HIGH)
  {
    Serial.println("2");
  }
   if (digitalRead(3)==HIGH && digitalRead(4)==HIGH)
  {
    Serial.println("3");
  }
   if (digitalRead(1)==HIGH && digitalRead(5)==HIGH)
  {
    Serial.println("4");
  }
    if (digitalRead(2)==HIGH && digitalRead(5)==HIGH)
  {
    Serial.println("5");
  }
    if (digitalRead(3)==HIGH && digitalRead(5)==HIGH)
  {
    Serial.println("6");
  }
    if (digitalRead(1)==HIGH && digitalRead(6)==HIGH)
  {
    Serial.println("7");
  }
    if (digitalRead(2)==HIGH && digitalRead(6)==HIGH)
  {
    Serial.println("8");
  }
    if (digitalRead(3)==HIGH && digitalRead(6)==HIGH)
  {
    Serial.println("9");
  }
}
2

I get a whole bunch of P's and @ signs.

Well you shouldn't get that from the code you posted.

How have you wired it up?
Are you going direct to the RS232 port and not through the USB? If so you need an RS232 to TTL converter chip.

3

I have it wired straight from my arduino to my computer's external USB plug. I've never had this problem during the month that I've owned an arduino.

4 
void loop()
{
  for (current=0;current<count;current++)
  {
    digitalWrite(pins[current],HIGH);
    digitalWrite(pins[current],LOW);

Looks to me like everytime through your loop() function you are 'stepping on top of' pins 0 and 1 which are the serial data pins. If you expect to use serial commands back to the PC you need to make sure you don't perform any digitalWrite() commands to pins 0 and 1.

Lefty

5 
  for (current=0;current<count;current++)
  {
    digitalWrite(pins[current],HIGH);
    digitalWrite(pins[current],LOW);
  }

With no delay between setting the pin HIGH and setting it LOW, what are you accomplishing?

  if (digitalRead(1)==HIGH && digitalRead(4)==HIGH)

You're reading from an OUTPUT pin that you have set LOW. You don't really expect to read HIGH do you?

6

PaulS:

  for (current=0;current<count;current++)

{
   digitalWrite(pins[current],HIGH);
   digitalWrite(pins[current],LOW);
 }



With no delay between setting the pin HIGH and setting it LOW, what are you accomplishing?

if (digitalRead(1)==HIGH && digitalRead(4)==HIGH)



You're reading from an OUTPUT pin that you have set LOW. You don't really expect to read HIGH do you?

More importantly I think, leaving that code with pin 1 at a LOW state is putting a 'break' condition (or start condition depending on the timing) of the serial link back to the PC, so sure to upset the next serial output command.

Lefty