need help with communication serie

Projects Programming
1

firstly, im using cable db9 for this serial communication...

void setup(){
Serial.begin(9600);
}

void loop(){
Serial.println("Hello");
delay(500);
}

im testing this code and its all ok..but when im testing the code below, its not functionned..can someone give me a help on this please...

void setup()
{
Serial.begin(9600);
pinMode(13, OUTPUT);
}

void loop()
{
if (Serial.available() > 0)
{
int incoming = Serial.read();

if ((char)incoming == '1')
{
digitalWrite(13, HIGH);
Serial.println("On");
}
else if ((char)incoming >= '2')
{
digitalWrite(13, LOW);
Serial.println("Off");
}
}
}

im using cable db9 and max 232 for make my wiring...when im using USB cable,there is no problems...

2

show how you make the db9<->max232<->arduino schema...

3

this is the link where i found the circuit...i make this wiring for my serial...avrprogrammers.com -

4

try with this schema while it talks about pin 15 and 16 of the max232.

I dont use the capacitor between VCC and Ground on the left bottom of the schema.

5

its fonctionned now...thanks a lot for ur help..
the problems just the ground...thanks