use getchar() in codevisionAVR

[Dhans42]

Im using getchar() in codevisionAVR

but my program got stuck. the function getchar() didn't execute and stop all of my code. im using hyperterminal to test this program. please help.

/*******************************************************
This program was created by the
CodeWizardAVR V3.12 Advanced
Automatic Program Generator
© Copyright 1998-2014 Pavel Haiduc, HP InfoTech s.r.l.
http://www.hpinfotech.com

Project :
Version :
Date    : 8/2/2024
Author  :
Company :
Comments:


Chip type               : ATmega128A
Program type            : Application
AVR Core Clock frequency: 8.000000 MHz
Memory model            : Small
External RAM size       : 0
Data Stack size         : 1024
*******************************************************/

#include <mega128a.h>
#include <delay.h>
#include <stdlib.h>
#define led1 PORTB.4
#define led2 PORTB.5
#define led3 PORTB.6
#define led4 PORTB.7
#define pb1 PIND.0
#define pb2 PIND.1
#define pb3 PIND.2
#define pb4 PIND.3

char baca;
// Declare your global variables here

#define DATA_REGISTER_EMPTY (1<<UDRE0)
#define RX_COMPLETE (1<<RXC0)
#define FRAMING_ERROR (1<<FE0)
#define PARITY_ERROR (1<<UPE0)
#define DATA_OVERRUN (1<<DOR0)

// USART0 Receiver buffer             
#define RX_BUFFER_SIZE0 8
char rx_buffer0[RX_BUFFER_SIZE0];

#if RX_BUFFER_SIZE0 <= 256
unsigned char rx_wr_index0=0,rx_rd_index0=0;
#else
unsigned int rx_wr_index0=0,rx_rd_index0=0;
#endif

#if RX_BUFFER_SIZE0 < 256
unsigned char rx_counter0=0;
#else
unsigned int rx_counter0=0;
#endif

// This flag is set on USART0 Receiver buffer overflow
bit rx_buffer_overflow0;

// USART0 Receiver interrupt service routine
interrupt [USART0_RXC] void usart0_rx_isr(void)
{
char status,data;
status=UCSR0A;
data=UDR0;
if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
   {
   rx_buffer0[rx_wr_index0++]=data;
#if RX_BUFFER_SIZE0 == 256
   // special case for receiver buffer size=256
   if (++rx_counter0 == 0) rx_buffer_overflow0=1;
#else
   if (rx_wr_index0 == RX_BUFFER_SIZE0) rx_wr_index0=0;
   if (++rx_counter0 == RX_BUFFER_SIZE0)
      {
      rx_counter0=0;
      rx_buffer_overflow0=1;
      }
#endif
   }
}

#ifndef _DEBUG_TERMINAL_IO_
//ubah ASCII ke desimal
#define _ALTERNATE_GETCHAR_
#pragma used+
char getchar(void)
{
char data;
while (rx_counter0==0);
data=rx_buffer0[rx_rd_index0++];
#if RX_BUFFER_SIZE0 != 256
if (rx_rd_index0 == RX_BUFFER_SIZE0) rx_rd_index0=0;
#endif
#asm("cli")
--rx_counter0;
#asm("sei")
return data;
}
#pragma used-
#endif

#define TX_BUFFER_SIZE0 8
char tx_buffer0[TX_BUFFER_SIZE0];

#if TX_BUFFER_SIZE0 <= 256
unsigned char tx_wr_index0=0,tx_rd_index0=0;
#else
unsigned int tx_wr_index0=0,tx_rd_index0=0;
#endif

#if TX_BUFFER_SIZE0 < 256
unsigned char tx_counter0=0;
#else
unsigned int tx_counter0=0;
#endif

interrupt [USART0_TXC] void usart0_tx_isr(void)
{
if (tx_counter0)
   {
   --tx_counter0;
   UDR0=tx_buffer0[tx_rd_index0++];
#if TX_BUFFER_SIZE0 != 256
   if (tx_rd_index0 == TX_BUFFER_SIZE0) tx_rd_index0=0;
#endif
   }
}

#ifndef _DEBUG_TERMINAL_IO_
// konversi ASCII ke desimal
#define _ALTERNATE_PUTCHAR_
#pragma used+
void putchar(char c)
{
while (tx_counter0 == TX_BUFFER_SIZE0);
#asm("cli")
if (tx_counter0 || ((UCSR0A & DATA_REGISTER_EMPTY)==0))
   {
   tx_buffer0[tx_wr_index0++]=c;
#if TX_BUFFER_SIZE0 != 256
   if (tx_wr_index0 == TX_BUFFER_SIZE0) tx_wr_index0=0;
#endif
   tx_counter0++;
   }
else
   UDR0=c;
#asm("sei")
}
#pragma used-
#endif

// Standard Input/Output functions
#include <stdio.h>

interrupt [TIM0_OVF] void timer0_ovf_isr(void)
{
// Reinitialize Timer 0 value
TCNT0=0xB2;
// Place your code here
a++;
}

void main(void)
{
// Declare your local variables here

// Input/Output Ports initialization

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 7.813 kHz
// Mode: Normal top=0xFF
// OC0 output: Disconnected
// Timer Period: 9.984 ms
ASSR=0<<AS0;
TCCR0=(0<<WGM00) | (0<<COM01) | (0<<COM00) | (0<<WGM01) | (1<<CS02) | (1<<CS01) | (1<<CS00);
TCNT0=0xB2;
OCR0=0x00;

// USART0 initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART0 Receiver: On
// USART0 Transmitter: On
// USART0 Mode: Asynchronous
// USART0 Baud Rate: 9600
UCSR0A=(1<<RXC0) | (0<<TXC0) | (0<<UDRE0) | (0<<FE0) | (0<<DOR0) | (0<<UPE0) | (0<<U2X0) | (0<<MPCM0);
UCSR0B=(1<<RXCIE0) | (1<<TXCIE0) | (0<<UDRIE0) | (1<<RXEN0) | (1<<TXEN0) | (0<<UCSZ02) | (0<<RXB80) | (0<<TXB80);
UCSR0C=(0<<UMSEL0) | (0<<UPM01) | (0<<UPM00) | (0<<USBS0) | (1<<UCSZ01) | (1<<UCSZ00) | (0<<UCPOL0);
UBRR0H=0x00;
UBRR0L=0x33;

// Global enable interrupts
#asm("sei")

while (1)
      {   
      baca=getchar();
      putchar(baca);
      }
}

 

[KlausST]

Hi,

getchar() ... most probably is a blocking function. (maybe there is a setup for a timeout --> read documentation.)

Thus it waits for a (valid) character to be received via the interface.
Without knowing more detailes I´d say it is working like expected.

Now some questions:
* did you read getchar() documentation. (usuage, setup, parameters, alternatives, other interface functions ...)
* HOW did you detect it got stuck?
* HOW do you expect it to operate?
* Are you sure your interface receives (valid) data?

You built an endless loop, so even it receives data ... it is expected to spend most of the time in getchar().


Klaus

 

[Dhans42]

wow tq klaus, its work now