please can anyone help me with the serial port comunication?
I dont have any experience with serial port comunication, so please try to understand my probably silly questions
what i need:
I want to send message consisting of the letter (char) and number. For example something like this : K1002
Is it possible? How to do it?
I have device that is controled by serial port and there is predefined some messages, that control the unit. But the controling messages consists always of some letter and numbers...
Hi Jura, perhaps something like this will help you get started:
void sendMessage(char letter, int number){
Serial.print(letter);
Serial.print(number,DEC); //Serial.println(number,DEC); // use this instead of the above if a carriage return/ line feed is expected by your device
}
example: sendMessage('K', 1002);
A read of the the Arduino Serial documention will explain what these commands do
Thanks a lot!
Works perfectly. Now I undertsand a little bit more.
But now I have other problem that I cannot solve now (its hard way...)ú:
I want to send by serial port the number that alway consist of 4 numbers, even it means zero. Like 0000. But I want to increase/decrease this number (by button) and always I need to be there all 4 numbers.
What happens now is, that it prints simple numbers without zeros before it - like this: 0, 2, 33, 455, 1024
but I need to print this: 0000, 0002, 0033, 0455, 1024
(its just example of the numbers...)
Is it possible to do it?
HOW? :-X
Thank you very much!!!!
here is a modified version that pads leading zeros
void sendMessage(char letter, int number){
// this version pads leading zeros so all numbers are four digits
// number must be less than or equal to 9999
Serial.print(letter);
int padding = 4;
int temp = number;
while( temp /= 10 )
padding--;
while( padding--)
Serial.print("0");
Serial.print(number,DEC);
//Serial.println(number,DEC); // use this instead of the above if a carriage return/ line feed is expected by your device
}
It's not tested so may need a little work But i hope it give you an idea of how to solve yr problem
I love mem's code, but it is just a little subtle. Let me see if I can annotate.
/* We're going to assume we want to pad with three zeros to start with */
int padding = 3;
/* Make a copy of the number, because we are going to dissect it. */
int temp = number;
/* In C, a while loop continues as long as the expression in parentheses is non-zero.
The expression "temp /= 10" divides temp by 10. The value of the expression is
temp after the division. So for example, if temp started out as 89, the value of the
expression would first be 8 and then 0. So for a 2-digit number, the loop executes once. For
a 3-digit number, it executes twice. For a 1-digit number, not at all. Each time through
it reduces the number of pad characters (padding--) */
while( temp /= 10 )
padding--;
/* This loop prints a leading zero once for each "padding". Each time through "padding"
is reduced by one and the loop terminates once padding reaches 0. So if padding is 3,
three 0's will be printed. */
while( padding--)
Serial.print("0");
Is it possible to send and array by serial port???
something like this:
int zones[] = (zone1, zone2, zone3......,zone 10); // the array of all
zones values - the
zone values are read
on 10 digital input
pins
void setup() {
Serial1.begin(9600);
etc... declare all input pins
void loop () {
zone1 = digitalRead (zone1Pin); // here I expect, that
if the value
on pin will be HIGH, the value zone1
will be 1, else 0 / is it right?
zone2 = digitalRead (zone1Pin);
etc......
Serial1.print (zones); // now I expect that this will
send the whole
array if numbers - something like
(1,0,0,0,1,0,1,0,1,1) - is it right?
delay (25); // here I expect, that the values will be hold and
sending about 25ms untill new measure loop / is it right?
}
Is it possible somehow?
There is not the array not written as a possible data for serial.print in reference :-/
What I want is to send the packet of all 10 values at once - each digit might represent the state of the input pin.
Maybe very simple, but I am still beginner
In C, you cannot pass an array to a function. The best you can do is pass a pointer (memory address). "int *array" means that array is a pointer to an integer, i.e. the first element of the array. Later, the "Serial.println(*array++)" means "print the integer that 'array' is currently pointing to and then point it to the next one in the array". This concept usually takes some time to understand, so don't be disillusioned if you don't immediately get it.
so the * prints the array value as int?
Whats the problem of this code, that it prints each digits on a new line.
So I need
Serial.print (*array++); // but here must be somehow condition to do it
untill the 9th number in array / HOW?
but the last 10th digit must be:
Serial.println(*array[9]);
Becouse I want to send the whole number at once like
0111000010
just read the incoming serial data (sending with 9600baud) and identicaly reprint them (in speed 115200baud).
The UART in the Arduino can't operate at split speeds. You would have to make one serial port using the software serial port extensions.
if ( Serial1.read() == Z09)
It depends what Z09 is. If it is a variable that contains an ASCII byte you want to trigger on then yes it will work. However, if it is an ASCII string then no it won't. You need to gather your string using multiple serial reads and then do a string compare.
Z09 or to be more exatact Z1 is a message sended by this code (from other board).
Serial.print ("Z");
Serial.println (1,DEC);
so it is not string( I hope - I am not common with string...).
Will this work?
AD 1.] So the reading and reprinting is not possible in differnet speeds?
The setup is like this:
arduino 1 is sending serial messgaes atd speed 9600 baud. This speed is chosen because the distance to second arduino is about 40m and its better to use slower speed.
arduino2 read this messages (if it possible it can read at 115200 / the Serial.begin (115200) will be set) and than indeticla z reprint this messages in speed 115200 to serial output.
The reason is simple - the driven unit need 115200badu speed, but the distance from the first arduino is cca 40m and I am afraid of some errors in hiugh speed....
No. You only have one byte in the read and you have sent two bytes. You have to convert them into a string or pack them into a single variable. (you can get two bytes in an int) like this:-
pack = byte1 | (byte2 <<8);
Then you can compare the ints.
So the reading and reprinting is not possible in differnet speeds
If you have something coming in when you are at a different speed sending out you will miss it or get some corruption. The simplest way is to use a soft serial port.
Anyway, I can't see how the fast unit needs to be fast as it can only send data at the speed (data rate) it receives from the slow sender. So there is no advantage in sending it quickly the number of bytes per second is limited to how fast they come in.
