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Electronics => Electronics => Topic started by: superchiku on March 11, 2009, 03:15:11 AM

Title: serial wireless communicaton problem
Post by: superchiku on March 11, 2009, 03:15:11 AM

I using serial wireless communication for my new bot...i decided to test a sample program to switch a led on and off using serial communication...iam using an ask 433 mhz wireless transmitter for that and a bafo 810 usb to serial converter...

i connected pin 3 of db9 to the pin 13 of maxx 232

pin 12 of max 232 to the transmitter data pin

at the receiver side iam using the data pin to connect to the rxd pin of mcu....

at 1st before any serial command is issued i programmed the mcu to blnk the led...after i issue any commands then the blinking will stop and the led will be switched on or off according to my will...

if i transmit 'a' then the led will be switched on...if i transmit 'd' then the led will be switched off...iam using the atmega16 mcu at the receiver side and i have switched on global serial receive nterrupt on...but no matter wat i send from the pc the led kees on blinking as if the mcu is receiving no serial commands...the max 232 is fully operational and iam transmitting my data from a vb program
my serial port settings are
port no-com9
data bits-8
parity-none
stop bits-1


my vb programis tis...written in vb 2008 express edition

Code: [Select]

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        MsgBox("hi how are u")
        SerialPort1.Open()



    End Sub

    Private Sub Form1_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseClick
        MsgBox("u clicked")

    End Sub

 

    Private Sub switchon_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles switchon.Click
        SerialPort1.Write(Chr(97))




    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        SerialPort1.Write(Chr(100))

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        SerialPort1.Close()


    End Sub
End Class
and my mcu program is this

Code: [Select]

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

#define USART_BAUDRATE 38400
#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)

int f=0;

void portinitialize();
void uartinitialize();
void handleleft();
void handleright();
void bytedecision(char);


void portinitialize()
 {
  DDRD|=(1<<4);
  TCCR1B|=(1<<CS12);
  }

void uartinitialize()
 {
   UCSRB |= (1 << RXEN) | (1 << TXEN);   // Turn on the transmission and reception circuitry
   UCSRC |= (1 << URSEL) | (1 << UCSZ0) | (1 << UCSZ1); // Use 8-bit character sizes

   UBRRL = BAUD_PRESCALE; // Load lower 8-bits of the baud rate value into the low byte of the UBRR register
   UBRRH = (BAUD_PRESCALE >> 8); // Load upper 8-bits of the baud rate value into the high byte of the UBRR register

   UCSRB |= (1 << RXCIE); // Enable the USART Recieve Complete interrupt (USART_RXC)
   sei(); // Enable the Global Interrupt Enable flag so that interrupts can be processed
 }
void handleleft()
 {
  int m=0;
  PORTD&=~(1<<4);
 
  for(m=0;m<=100;m++)
  _delay_ms(10);
 }

void handleright()
 {
  int m=0;
  PORTD|=(1<<4);

  for(m=0;m<=100;m++)
  _delay_ms(10);
  }

void bytedecision(char a)
 {
  if(a=='a' || a=='A')
   {
    handleleft();
    }
  if(a=='d' || a=='D')
   {
    handleright();
   }
 }

int main (void)
{
   portinitialize();
   uartinitialize();
   
   for(;;) // Loop forever
   {
     if(f==0)
   
   
     {
 
    if(TCNT1>=31250)

{
  PORTD^=(1<<4);  // run test program blinking- echoing is handled by the ISR instead of in the main loop
  TCNT1=0;
}
}
 }
       
     
}

ISR(USART_RXC_vect)
{
   f=1;
   char ReceivedByte;
   ReceivedByte = UDR; // Fetch the recieved byte value into the variable "ByteReceived"
   //UDR = ReceivedByte; // Echo back the received byte back to the computer
   bytedecision(ReceivedByte);
}
plz this is long but do help me

Title: Re: serial wireless communicaton problem
Post by: superchiku on March 11, 2009, 11:30:47 AM

come on guys....help me...is there sumthing wrong in the code...??

Title: Re: serial wireless communicaton problem
Post by: Soeren on March 12, 2009, 11:45:48 PM

Hi,

Did you check the transmitter/receiver pair without the controllers?

Title: Re: serial wireless communicaton problem
Post by: superchiku on March 13, 2009, 12:46:31 AM

even witout the transmitter and receiver y code isnt workin i am ot able to sendanything...plzz do help me...i think here is sumtin wrong inthe code coz the max232 is working well...

Title: Re: serial wireless communicaton problem
Post by: Admin on March 25, 2009, 12:51:19 AM

Quote

a bafo 810 usb to serial converter...

Hmmm I think you should get a new USB to TTL serial (not rs232) adapter.

Also, did you do a loop-back test? When you put a multimeter (set to frequency) up to the Tx/Rx lines, what do you see?