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PIC16F882 UART issue

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Nandus2000

Joined: 17 Sep 2008
Posts: 10

PIC16F882 UART issue

Posted: Tue Oct 07, 2008 7:28 am

Hi

I'm using CCS 4.076 version with PIC16F882 and following is my code.
The putc() function inside the for loop does not work properly.

Please could you let me know how can I correct it?

Main.C

Code:

/**************************************************************************************************
System Includes
**************************************************************************************************/
#include <16F882.H>

/**************************************************************************************************
compiler directives using __PCM__ compiler
***************************************************************************************************/
// Preprocessor directive that defines the chip fuses
#fuses INTRC,NOWDT,NOPROTECT,NOPUT,BORV21
// Preprocessor directive that specifies clock speed
#use delay(clock=4M)
// Preprocessor directive that includes RS232 libraries
#use RS232(BAUD=19200, BITS=8, PARITY=N, STOP=1, XMIT=PIN_C6, RCV=PIN_C7, ERRORS)

/**************************************************************************************************
User Includes header files
***************************************************************************************************/
#include "ControlUnit.h"
#include "ERROR_CODES.h"

/**************************************************************************************************
User source code files
***************************************************************************************************/
#include "RS232.C"

/**************************************************************************************************
Global variables
***************************************************************************************************/
//Push buttons press status flag
volatile BOOLEAN flg_B0_Pressed = FALSE;
volatile BOOLEAN flg_B1_Pressed = FALSE;

BOOLEAN g_bCameraON_OFF = TRUE;

/**************************************************************************************************
Function Name : isr_timer2
Description    : Interrupt service routine called every milli-second.
Parameters    : None
Returns       : None
****************************************************************************************************/
#int_timer2
void isr_timer2(void)
{
//Initialize g_LastB0B1 to set port B0 & B1 to high by default (connected to pull-ups).
static unsigned char g_LastB0B1 = 3;
volatile signed long iDelay = DEBOUNCE_DELAY;
unsigned char bChanges;

//Check B0 or B1 changed.
bChanges = (g_LastB0B1 ^ input_b());
g_LastB0B1 = input_b();

//Checking SW0/B0 and SW1/B1 if it goes High to Low
if( bit_test(bChanges,0) && (!bit_test(g_LastB0B1,0)) )
{ //B0 went to low
   flg_B0_Pressed = TRUE;
   //Debouncing wait.
   while(idelay --);
}
else if( bit_test(bChanges,1) && (!bit_test(g_LastB0B1,1)) )
{ //B1 went to low
   flg_B1_Pressed = TRUE;
   //Debouncing wait.
   while(idelay --);
}

//output_toggle(PIN_B7); // Usful for testing timer2 as a waveform on analyser 1mS wave.
}

/**************************************************************************************************
Function Name : main
Description    : Main - Start of Program
Parameters    : None
Returns       : None
****************************************************************************************************/
void main(void)
{
unsigned char byError = 65;
unsigned char ch;

   //Initialise RS232 communication
InitRS232();

//Setup up timer2 to interrupt every 1ms if using 20Mhz clock
setup_timer_2(T2_DIV_BY_4,79,16);

//Enable timer2 interrupt
   enable_interrupts(INT_TIMER2);

//Enable all interrupts (else timer2 wont happen)
   enable_interrupts(GLOBAL);

//Initialise, switch on & config the camera.
printf("Setting LED ON!!\r\n Variable value = %d\r\n", byError);
output_high(PIN_C2);

putc('.');
printf("%d\r\n", 49);
putc('N');

while(TRUE)
{
   putc('.');

//Check if Camera ON/OFF button pressed.
   if(flg_B0_Pressed == TRUE)
   {
      flg_B0_Pressed = FALSE;
      g_bCameraON_OFF = !g_bCameraON_OFF;
   }

   //Check if Spare button B1 / Key1 pressed.
if(flg_B1_Pressed == TRUE)
   {
      flg_B1_Pressed = FALSE;
   }

   if(IsDataAvailable() == TRUE)
   {
      ch = g_RxBuffer[g_Next_out];
      g_Next_out =(( g_Next_out + 1 ) % BUFFERSIZE);
      //printf("%c" ch);
      putc(ch );

   }
   delay_ms(300);
}
}

/***************************************************************************************************************************
End of the file
***************************************************************************************************************************/

RS232.C:

Code:

/**************************************************************************************************
Revision History
DD.MM.YYYY UID Description
24.09.2008 NPS First draft
***************************************************************************************************/

/**************************************************************************************************
System Includes
**************************************************************************************************/

/**************************************************************************************************
User Includes
***************************************************************************************************/
#include "RS232.h"

/**************************************************************************************************
Global variables
***************************************************************************************************/
//Global Rx buffer
unsigned char g_RxBuffer[BUFFERSIZE];
//Circular buffer positions initialisation
unsigned int g_Next_in = 0;
unsigned int g_Next_out = 0;

/**************************************************************************************************
Static variables
***************************************************************************************************/

/**************************************************************************************************
Function Name : InitRS232
Description    : Initialise RS232 buffer and enable the Rx interrupt.
Parameters    : None
Returns       : None
****************************************************************************************************/
void InitRS232(void)
{
//Initialise the message structure.
memset(g_RxBuffer, 0, BUFFERSIZE);

//Set up MAX232
output_high(RS232_FORCEON);
output_high(RS232_FORCEOFF_BAR);
output_low(RS232_ENABLE);

//Enbale Rx interrupt.
enable_interrupts(INT_RDA);
}

/**************************************************************************************************
Function Name : isr_rda
Description    : Interrupt service routine called wenever a byte received in RS232 Rx buffer.
Parameters    : None
Returns       : None
****************************************************************************************************/
#int_rda
void isr_rda(void)
{
unsigned int update_next_in;
unsigned char charIn;

//Read character temporary. If the buffer is full then drop the character.
   charIn = getc();

if(FALSE == BUFFER_FULL(g_Next_in, g_Next_out ) )
{
   //Store the character
   g_RxBuffer[g_Next_in] = charIn;

   //Calculate next in postion.
   update_next_in = ((g_Next_in + 1) % BUFFERSIZE);

   //Following is to avoid false buffer empty situation if both
      if( update_next_in != g_Next_out )
      {
      g_Next_in = update_next_in;
   }
   }
}

/**************************************************************************************************
Function Name : IsDataAvailable
Description    : This function is to provide status if there is any data avialable in RS232 Rx buffer.
Parameters    : None
Returns       : None
****************************************************************************************************/
BOOLEAN IsDataAvailable(void)
{
BOOLEAN bReturn;

bReturn = (g_Next_in == g_Next_out )? 0 :1;

return(bReturn);
}

/**************************************************************************************************
Function Name : GetBufChar
Description    : This function retrieves a byte from circular Rx buffer.
Parameters    : unsigned char* pChar - This will contain byte retried from circular Rx buffer.
Returns       : BOOLEAN 1 - Success
                  0 - Error / buffer empty.
****************************************************************************************************/
BOOLEAN GetBufChar(unsigned char* pChar)
{
BOOLEAN bReturn = FALSE;
volatile unsigned long ulGetChDelay = DELAY_GET_CHAR;

while( (bReturn == FALSE) && (ulGetChDelay !=0) )
{
   if( FALSE == BUFFER_EMPTY(g_Next_in, g_Next_out) )
      {
      *pChar = g_RxBuffer[g_Next_out];
      g_Next_out =(( g_Next_out + 1 ) % BUFFERSIZE);
      bReturn = TRUE;
   }
   else
   {
      ulGetChDelay--;
      //TODO: Reset WDT
   }
}
return(bReturn);
}
/***************************************************************************************************************************
End of the file
***************************************************************************************************************************/

O/p is:

Code:

Setting LED ON!!

Variable value = 65

.49

N..

PCM programmer

Joined: 06 Sep 2003
Posts: 21708


Posted: Tue Oct 07, 2008 10:49 am

You've posted a lot of code, probably more than we want to look at. But, you need to post the output that you want to see. You have posted the "bad" output. Post your desired output and post the bad output just below it, so we can compare them.

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