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adalucio
Joined: 16 Mar 2009
Posts: 29
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| RS232 Problem |
 Posted: Wed Jan 13, 2010 6:34 am |
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Hi. I have a 16f877 connected to a lcd and a rs232 xbee
| Code: |
#include <16F877A.h>
#device adc=8
#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES PUT //Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#use delay(clock=20000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
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| Code: |
#include "C:\pic\xbee_test\xbee_lcd_877\main.h"
#include <flex_lcd420.c>
#int_RDA
RDA_isr()
{
disable_interrupts(INT_RDA);
if(kbhit())
{
lcd_putc(getc());
}
enable_interrupts(INT_RDA);
}
void main()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
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);
setup_vref(FALSE);
lcd_init();
delay_ms(400);
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
printf(lcd_putc, "\fStarted");
while(1)
{
delay_ms(10);
}
}
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I see "Started" on lcd, but lcd_putc(getc()) don't work. I'm sure data arrives, because if I connect it to a pc I can see the data.
Help please
Thanks[/code] |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jan 13, 2010 12:41 pm |
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| Quote: | #int_RDA
RDA_isr()
{
disable_interrupts(INT_RDA);
if(kbhit())
{
lcd_putc(getc());
}
enable_interrupts(INT_RDA);
} |
The lines shown in bold are not necessary and should be deleted.
If you're in the RDA isr, you automatically have a "kbhit". You don't
need to check for it. Global interrupts are automatically disabled
while inside the isr, so you don't need to disable/enable RDA interrupts.
Also, there are no nested interrupts.
| Quote: | setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
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);
setup_vref(FALSE); |
None of this Wizard code is needed. All these modules are disabled
upon power-on reset. The CCS start-up code sets Port A to be all
digitial. The setup_spi() statement, as shown, will actually enable
the SPI module. In some PICs that share the SDO pin with the UART
Rx pin, this will stop the UART from receiving chars. (However, the
16F877A doesn't share a pin for Rx and SDO, so it's OK).
Delete all these lines.
| Quote: |
delay_ms(400);
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
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Here you have a large initial 400ms delay before interrupts are enabled.
It's possible that characters are coming into the UART during this time,
but they cannot be handled for 400 ms. If more than 2 characters come
in, this will exceed the capacity of the UART's hardware receive fifo.
This will cause the UART receiver to lock-up, and it will stay locked up.
You won't be able to receive any characters.
To fix this problem, add the ERRORS parameter to your #use rs232()
statement, as shown below. This will cause the compiler to add code
to check if a UART receiver overrun error has occurred, and if so, then
it will clear the error. This will prevent lock-ups. You will still lose the
characters that caused the overrun, but at least future characters can
be received.
| Quote: | | #use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7,ERRORS) |
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adalucio
Joined: 16 Mar 2009
Posts: 29
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| Posted: Thu Jan 14, 2010 3:23 am |
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WOW THANKS. now I'm your fan
if I wanted to deepen my studies on CCS pic, what book should I buy?
Thanks again
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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