clocks

Projects Programming
1

Hello,
I'm inexperienced and I need help.
When I write in serial monitor single digit number it set hours, next number sets minutes and next seconds. But when I write two-digit number it doesnt work, it sets hours and minutes with one two-digit number. It reads two-digit number as 2 characters and it isnt correctly

Thanks

int s = 0;
int m = 0;
int h = 0;
char charr;

void setup() {
Serial.begin(9600);
Serial.println("Hours");
while(h==0){
if (Serial.available() > 0) {charr = Serial.read();
h = charr-48;
Serial.println(h);}

}
Serial.println("Minutes: ");
while(m==0)
{ if (Serial.available() > 0) {charr = Serial.read();

m = charr-48;
Serial.println(m);}
}
Serial.println("Seconds ");
while(s==0){
if (Serial.available() > 0) {charr = Serial.read();
s = charr-48;
Serial.println(s);}

}
}

void loop() {

s++;

if (s > 59){s=0 ; m++;}
if (m > 59){m=0 ; h++;}
if (h > 23){h =0;}
if (h<10) {Serial.print("0");}; Serial.print(h); Serial.print(":"); if (m<10){Serial.print("0");}; Serial.print(m); Serial.print(":"); if (s<10) {Serial.print("0");};Serial.println(s);
delay(1000);
}

2

It reads two-digit number as 2 characters and it isnt correctly

But that is what you told it to do. How is the Arduino supposed to know that that isn't what you meant?

How is the Arduino supposed to know that you sometimes want to send a one digit number and sometimes a two digit number?

Robin2 has a great thread on reading serial data. Serial Input Basics - updated - Introductory Tutorials - Arduino Forum

3

I cant explaint it.. When I write for example 20 it doesnt set 20 o'clock but 2hours and 0 minutes and

4

Look for two receive characters before you set h,m,s.
For example: 06 to set to 6

Serial.available() = 2 or > 1

.

5

I cant explaint it.

If you can't put your requirements into words, how can you possibly put them into code?

6

Take a look at this and see if you get any ideas:

void loop() {
   char buffer[10];    // Could be smaller...
   int charsRead;
   int minutes;

   if (Serial.available() > 0) {

      charsRead = Serial.readBytesUntil('\n', buffer, sizeof(buffer) - 1);

      buffer[charsRead] = '\0';       // make it into a C string
      minutes = atoi(buffer);
      Serial.print("Minutes = ");
      Serial.println(minutes);
   }
}

More importantly, why does it work the way it does. The readBytesUntil() method reads the input stream from the Serial object until it sees a newline character (i.e., the user pressed Enter) or the buffer has 9 characters in it. It returns the number of characters read, which we save in charsRead. We need to save one element for the NULL character which terminates the C string. This code assumes you have the Newline option set in the textbox at the bottom of the Serial monitor.

7

thanks for ideas