passing xbee data to lcd

Comments

• Electrodude Posts: 1,621

  2015-01-16 16:10 edited 2015-01-16 16:10

  I'm not sure you understand brackets properly. This might just be the forum being stupid, but code is a lot more readable and mainainable (= fixable) if you have consistent indentation.
  
  Transmitter:

    while(1)                                          // Loop repeats indefinitely
    {
      volts = adc_volts(0) * 2;                       // Check A/D 0 and double value
                 
      putChar(HOME);                                   // Cursor -> top-left "home"
      { // why is this here?
      print("Volts = %f\n", volts, CLREOL);            // Display voltage on terminal (if connected)
      }     
      { // why is this here?
        dprint (xbee, "%f\n",  volts, CLREOL);        // send votage variable to the xbee
      }
               
    pause(1000);                                      // wait 1 second                                
   }     
  

  
  Receiver:

  while(1)                                       // loop....this is line 36
  {
  data = fdserial_rxChar(xbee);                  // receive xbee data
  if(data != -1); // useless if statement
  }                                              // this is line 40
    
  { // never gets called - outside of loop
  writeFloatPrecision(lcd, data, 5, 3);          // send received data to devices as 5 characters total, precision of 3
  writeFloatPrecision(term, data, 5, 3); 
  }
  
  

  
  For the receiver, did you mean:

  while(1)                                       // loop....this is line 36
  {
       data = fdserial_rxChar(xbee);                  // receive xbee data
      if(data != -1)  // no semicolon
      {
          writeFloatPrecision(lcd, data, 5, 3);          // send received data to devices as 5 characters total, precision of 3
          writeFloatPrecision(term, data, 5, 3); 
      }
  }
  

  
  Note that

  if (whatever);
  

  is useless; since whitespace doesn't matter in C, it's the same as

  if (whatever)
      ;
  

  which means "if whatever then don't do anything, and then go on" (not else).
• SCAS Posts: 3

  2015-02-23 18:54 edited 2015-02-23 18:54

  When you send a float over a uart, you must break it up from a single 32 bit float into 4 - 8 bit chars or uint8's you cant just shift these 4 bytes together to make a float. Because it is 4 chars. Not one float. You must assemble these 4 bytes into a single 32 bit uint then cast it into a float. Then it will display.
• oswaldzimbango Posts: 1

  2017-10-20 09:14

  i also have a mini project that i am trying to do that involves displaying the received data from the xbee onto a 16*2 lcd..both the lcd and xbee are connected to an arduino uno board. below are the connections i made..i want to broadcast the state of the traffic light on a remote lcd display

  

  

  proteus.png

  5746 x 2446 - 311K

  proteus.png 310.6K
• dgately Posts: 1,621

  2017-10-21 03:24

  
  Sending serial data as in:
  

  dprint (xbee, "%f\n",  volts, CLREOL);
  

  Sends the float variable, 'volts' as a text string (as an example "4.735"). You need a way to convert the text string back into a float. In the following example (not tested as I'm not running an XBee right now), dscan is used to turn the sent string back into a float type.
  

  /*
  receive voltage over xbee and display on lcd and terminal
  */
  #include "simpletext.h"
  #include "simpletools.h"                 // Include required libraries
  #include "serial.h"
  #include "fdserial.h"
  
  fdserial *xbee;
  serial *lcd;
  serial *term;
  
  int main()
  {
  const int ON = 22;
  const int CLR = 12;
  float data;                               // declare data variable as type float
    
    xbee = fdserial_open(7, 6, 0, 9600);    // initialize devices
    lcd = serial_open(13, 13, 0, 9600);
    term = serial_open(31, 30, 0, 115200);                      
  
    writeChar(lcd, ON);                     // prepare LCD to receive data
    writeChar(lcd, CLR);
    pause(1000);
  
    int count;
      
    while(1)
    {
      count = fdserial_rxCount(xbee);            // check to see if there are characters in the serial buffer
  
      if(count > 0)                              // only convert if there is some data to convert
      {  
        count =  dscan(xbee, "%f\n", data);      // reads in a text string, converting it to the specified format
        writeFloatPrecision(lcd, data, 5, 3);    // send received data to devices as 5 characters total, precision of 3
        writeFloatPrecision(term, data, 5, 3); 
        fdserial_rxFlush(xbee);                  // clear out the serial buffer
      }
    }     
  }
  

  
  This code does not correctly assess the data in the incoming serial buffer, just checks to see if there's anything at all in the buffer. For correctness, the code should do a better job of qualifying the input before attempting to write it out...
  
  There are several other ways to "skin this cat", but dscan seems simple. The C language's standard libraries offer conversion functions that could also be used.
  
  
  dgately