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akshaymathur39
Joined: 05 Aug 2008
Posts: 11
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| PIC16F887 #int_rda problem. |
 Posted: Sat Aug 09, 2008 9:22 pm |
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Hello Friends,
I have written a simple code of using USART receive interrupt system. When the data is received, it jumps to the interrupt function and blinks the led in the function loop with less delay. As soon as it comes out of the interrupt blinking loop, it again enters the same loop detecting interrupt. Its like it keep running in the interrupt loop. I doubt that may be interrupt flag is not cleared when it jumps back to main loop. Please have a look at the code.
| Code: | #include "C:\Documents and Settings\Akshay Mathur\Desktop\RS232 test\rs232.h"
int i=0,j;
byte buf[3];
#int_RDA
void RDA_isr(void)
{
for(j=0;j<10;j++){output_low(PIN_C0);delay_ms(45);output_high(PIN_C0);delay_ms(45);}
}
void main()
{
setup_adc_ports(sAN0|sAN1|sAN2|sAN3|sAN4|sAN5|sAN6|sAN7|VSS_VDD);
setup_adc(ADC_CLOCK_INTERNAL);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);// This device COMP currently not supported by the PICWizard
enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);
//Setup_Oscillator parameter not selected from Intr Oscillotar Config tab
// TODO: USER CODE!!
while(TRUE){
output_low(PIN_C0);
delay_ms(500);
output_high(PIN_C0);
delay_ms(500);
}
} |
Header details:
| Code: | #include <16F887.h>
#device adc=10
#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz)
#FUSES NOPUT //No Power Up Timer
#FUSES MCLR //Master Clear pin enabled
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOCPD //No EE protection
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES NOFCMEN //Fail-safe clock monitor disabled
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOWRT //Program memory not write protected
#FUSES BORV40 //Brownout reset at 4.0V
#use delay(clock=8000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
#use i2c(Master,Fast,sda=PIN_C4,scl=PIN_C3) |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Aug 09, 2008 10:40 pm |
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| Quote: |
#int_RDA
void RDA_isr(void)
{
for(j=0;j<10;j++)
{
output_low(PIN_C0);
delay_ms(45);
output_high(PIN_C0);
delay_ms(45);
}
}
Its like it keep running in the interrupt loop |
The clue is in the 16F8887 data sheet:
| Quote: | 12.1.2.3 Receive Interrupts
The RCIF interrupt flag bit of the PIR1 register is set
whenever the EUSART receiver is enabled and there is
an unread character in the receive FIFO. The RCIF
interrupt flag bit is read-only, it cannot be set or cleared
by software.
RCIF interrupts are enabled by setting the following
bits:
• RCIE interrupt enable bit of the PIE1 register
• PEIE peripheral interrupt enable bit of the
INTCON register
• GIE global interrupt enable bit of the INTCON
register
The RCIF interrupt flag bit will be set when there is an
unread character in the FIFO, regardless of the state of
interrupt enable bits. |
Question: What should you do inside the #int_rda isr to
remove this condition ?
Question #2: If you have massive delays inside your #int_rda isr,
what happens when characters keep coming in, but your isr can't do
anything about them, because it's stuck doing the massive delays ? |
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