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Message |
Gsmar
Guest
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| Always in #INT_RDA |
 Posted: Thu Apr 27, 2006 4:40 am |
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Hi,
I'm having problems with #INT_RDA, because I don't send any data via RS232 and PIC is always in this interrupt (Even if I disconnect the uart pins)
I use PIC16F873.
I need help. How can I stop the INT_RDA?
The code is:
| Code: |
#include <16F873.h>
#fuses HS,NOWDT,NOPROTECT,NOBROWNOUT,NOLVP
#use delay(clock=8000000)
#use fast_io(A)
#use fast_io(B)
#use fast_io(C)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, bits=8, parity=N)
#define LED1 PIN_A2
#define LED2 PIN_A3
#define LED3 PIN_B3
int1 flag_SO;
int1 rx; //Para activar la recepcion del puerto RS232
#INT_RDA
void intrda_isr(void)
{
output_high(LED1);
output_high(LED3);
output_high(LED2);
}
#INT_EXT
void ext_isr()
{
flag_SO=1;
}
// ------------------------Configuracion del PIC -----------------------------//
void config_pic(void)
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
// Configuraci�n de los puertos del PIC
SET_TRIS_A(0x00); // configuramos todos los pines como salidas
SET_TRIS_C(0x80); //1000 0000: C7:entrada, resto y C6:salida
}
//--------------------------MAIN----------------------------------------------//
void main (void)
{
config_pic();
enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);
enable_interrupts(INT_EXT);
ext_int_edge( L_TO_H );
output_low(LED1);
output_low(LED2);
output_low(LED3);
rx=0;
while(1)
{
if(rx==1){
rx=0;
//AQUI REALIZABA UN GETS();
}else{ //del rx==1
output_low(LED1);
output_low(LED2);
output_low(LED3);
if (flag_SO==1)
{
flag_SO=0;
printf("PRUEBA");
}
}//fin else
}//fin while(1)
}//fin main
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Thanks in advance for your help. |
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RHA
Joined: 25 Apr 2006
Posts: 31
Location: Germany
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| Posted: Thu Apr 27, 2006 5:11 am |
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I think you have to read out the receive buffer in the interrupt service routine to clear the flag for the interrupt.
Greets
RHA |
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Guest
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| Posted: Thu Apr 27, 2006 5:32 am |
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| RHA wrote: | I think you have to read out the receive buffer in the interrupt service routine to clear the flag for the interrupt.
Greets
RHA |
I have tested it and I have to do a getc(). But if I want to do a gets() I have problems.
I've found out an error in CCS. Initially the usart interrupt flag is enable and so when I enable INT_RDA, I enter in this interruption.
I think the solution is to do a getc() before enable_interrupts(INT_RDA), but this in't correct. |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Apr 27, 2006 6:30 am |
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| No, you would receive the data into a buffer. From main, you can check this buffer for your string. |
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Guest
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| Posted: Thu Apr 27, 2006 8:11 am |
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| Mark wrote: | | No, you would receive the data into a buffer. From main, you can check this buffer for your string. |
The problem is that if I don't send any data by RS232, PIC doesn't have enter in UART interrupt (INT_RDA) when I start my program |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Apr 27, 2006 9:06 am |
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| Anonymous wrote: | | Mark wrote: | | No, you would receive the data into a buffer. From main, you can check this buffer for your string. |
The problem is that if I don't send any data by RS232, PIC doesn't have enter in UART interrupt (INT_RDA) when I start my program |
I have no idea what you are trying to say. There is no problem with what I suggested. Maybe with you understanding though. Why do you think that your PIC needs to enter UART interrupt when program starts? The PIC will only enter the interrupt when an even occurs. If no RS232, then no data in buffer. I guess you need to better describe what you are trying to do. |
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drh
Joined: 12 Jul 2004
Posts: 192
Location: Hemet, California USA
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| Posted: Thu Apr 27, 2006 12:21 pm |
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Guest, from the data sheet "Flag bit RCIF is a read only bit, which is cleared by the hardware. It is cleared when the RCREG has been read and is empty".
You have enabled this interrupt in your code but in your interrupt handler you are not reading from the RCREG. Is this why you stay in the interrupt routine?
Read the data sheet.
_________________
David |
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dbotkin
Joined: 08 Sep 2003
Posts: 197
Location: Omaha NE USA
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| Posted: Thu Apr 27, 2006 1:20 pm |
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According to the 16F873 date sheet the RCIF bit *should* be cleared by a reset, so in theory you shouldn't see INT_RDA unless the USART thinks it has data.
That said, the USART can think it has data if you have, for example, a floating input or some other hardware oddness that allows the USART to think it's seen a start bit.
Here's what I would do: First, add ERRORS to your #use rs232 statement. I've never had a project work right without it. Second, read RCREG inside your serial ISR; this will clear RCIF and keep you from constantly looping into it if and when RCIF gets set.
It would be interesting to know why RCIF is getting set when it shouldn't. You can work around it with a little bit of code, but it's best not to let those unexplained things slide, even if you do work around them. Digging until you find the source of the problem is a good way to learn, and will often keep other problems from coming up later on. |
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Gsmar
Guest
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| Posted: Fri May 05, 2006 4:53 am |
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| Thanks for your help. Finally I solve the problem. The device I connect to the uart, at the begining it sends a character and I don't read this, and so The pic always is on interrupt. |
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