next topic »

[on:]

Hi there i try to send an recive data by tx an rx.

On the first board i send data by Serial.print (CODE: Serial.print(123, DEC)), at the other board i want to read this data by Serial.read();. so far it works i recive data, but it is not the value i aspekted. At the Serial Monitor at the first screen arduino printed "123", but at the Monitor of the second board i get a totaly diffrent value.

Also if i try to send an read a binary, but value there are no similar values in the string.

Can anybody help me?

PS: Sorry for my english.

[Reply #1 on:]

Can you post your code?

Serial.print(123, DEC) sends three bytes of serial data: the characters '1', '2', '3' (e.g. 49, 50, 51).  To receive the value on the other board, you'll need to collect these bytes and reassemble them into a value.  E.g. each time you get a byte, you want to do something like:

Code:

int c = Serial.read();
int digit = c - '0';  // '0' == 48: the ASCII value of the digit 0
value = value * 10 + d;

You'll need to send some sort of terminating character (like a newline) and check for that on the receiving end.

Alternatively, you can just send binary bytes (remember a byte only goes from 0-255) or multiple bytes, but then you won't be able to read the data in the serial monitor.

[Reply #2 on:]

Ok, i undersand, thanks so far. And i could encode the data. But at least i have one error. If i start to send just one byte nothing happend. To start the communication i had to send 2 or 3 bytes in one Serial.print();. When ist is runnig i can refresh my sending script to one byte only. :-?

Is there any reason why i had to do this, it is a not so good if i had to change the input to start the conversation. Any meanings?

[Reply #3 on:]

That's strange.  Can you post the code that has problems?  Do you have trouble reading the data with the computer or another Arduino board?

[Reply #4 on:]

So i watch this problem during my test and seems it alway needs be pushed. After this it works fine.

TRANSMITTER CODE:
------------------------------------------------------------
void setup() {
  // open the serial port at 9600 bps:
  Serial.begin(9600);
}

void loop() {
  // print it out
  Serial.print(9215, DEC);    // print as an ASCII-encoded decimal
  delay(70);
}
-------------------------------------------------------------------


REVEIVER CODE:
-------------------------------------------------------------------
int incomingByte = 0;      // for incoming serial data
int empfaenger = 0;
int sender = 0;
int eigenschaft = 0;
int zaehler = 0;

void setup() {
  Serial.begin(9600);      // opens serial port, sets data rate to 9600 bps
}

void loop() {

  incomingByte = Serial.read();
  Serial.print(incomingByte);
    

}
------------------------------------------------------------------------

So if i start this two Codes on diffrent boards nothing will happend. i have to chang my value (9215) in 215. When this script is started, the other board begins to read data.

But it is a little bit strange, because if the transmitter-board send or not, the receiver board must print something, for example -1. If i cut the connetion the receiver-boards print -1, but just after i give him a little kick.

Any ideas?

[Reply #5 on:]

Hmm, strange, I'll try to take a look (when I get a moment of free time from my thesis).