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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| PIC 16F877 USART Interrupt problem |
 Posted: Sat Jun 06, 2009 11:33 am |
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Hello! I have got a problem using the USART interrupt. My code is the following…
| Code: |
#include <16F877A.h>
#FUSES XT, NOWDT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay (clock = 4000000)
#use rs232(baud=9600, Bits=8, Parity=N, xmit=PIN_C6, rcv=PIN_C7, stream=module)
#int_rda
void module_uart_isr()
{
output_high(led3);
delay_ms(400);
output_low(led3);
delay_ms(400);
fgetc(module);
....Settings
}
void main()
{
....PIC settings
enable_interrupts(int_rda);
enable_interrupts(global);
while(1)
{
delay_ms(100);
}
}
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The problem is that I cannot go the interrupt service routine even if I am sending data to the PIC microcontroller. I haven’t got any hardware problem for sure, because I am using the same interface without problems but with not any USART interrupt. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Sat Jun 06, 2009 12:01 pm |
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Well, first of all thanks for the fast respond! But the problem remains!
I have totally remove the delays from the interrupt service routine and I am measuring the pin using an oscilloscope… Still nothing… |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jun 06, 2009 12:07 pm |
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Strip the program down so it's very simple. Don't use streams.
Just echo a received character back to the PC. Here's an example:
http://www.ccsinfo.com/forum/viewtopic.php?t=37380&start=3
Carefully check all your connections, including the PIC, the Max232 chip,
and the cable. |
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Sat Jun 06, 2009 3:35 pm |
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It’s already very simple program… and it is almost impossible not use the streams. I am trying to communicate with a GSM module and I have got strait connections between the PIC and the module. No MAX232 chips or any other interfacing circuit between them.
My hardware is 100% OK and tested with software’s without interrupts… the problem is the software that use interrupt service routines, but I don’t know what I have to do!
I was trying to debug the system looking for what happens with the INTCON reg, PIE1 reg and finally PIR1 reg. The only problem was that the bit 5 from the PIR1 reg was always 0 so it is almost impossible to have an interrupt because the buffer is empty! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jun 06, 2009 4:07 pm |
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If you tested it on a PC (with a MAX232 chip), then you would prove to
yourself that you can make an #int_rda routine work.
You don't need to debug the PIR1 register. Just make that sample
program work. |
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Ttelmah
Guest
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| Posted: Sun Jun 07, 2009 2:30 am |
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I'd suggest you triple check the hardware.
You have to understand, that RCIF, is a completely _hardware_ based bit. It _is_ set, automatically, if pin C7, goes low, for more than about 2/3rd the bit time. Nothing else is needed to trigger it.
Also, the standard getc routine, if you are reading data from the hardware UART, _uses this signal_.
The code, as posted by PCM_programmer, in thread 37380, - don't change it, except to select the 877, instead of 876, _will_ work, if your hardware is functional. If it doesn't, you have a hardware problem.
Best Wishes |
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Sun Jun 07, 2009 4:03 am |
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When I am using that program:
| Code: |
#include <16f877A.h>
#FUSES XT, NOWDT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay (clock = 4000000)
#use rs232(baud=9600, Bits=8, Parity=N, xmit=PIN_C6, rcv=PIN_C7, stream=Module)
#use rs232(baud=9600, Bits=8, Parity=N, xmit=PIN_C0, rcv=PIN_C1, stream=PC)
void main()
{
int i=0;
...Configurations...
while(1)
{
if (kbhit(PC))
{
i=fgetc(PC);
fputc(i,module);
}
if (kbhit(module))
{
i=fgetc(module);
fputc(i, PC);
}
}
}
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I can sent AT command from my PC to the GSM module and vice-versa, without any problem. So, it is almost impossible to have any hardware problem! |
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Ttelmah
Guest
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| Posted: Sun Jun 07, 2009 1:31 pm |
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So, if you use the code modified to give an interrupt version:
| Code: |
#include <16f877A.h>
#FUSES XT, NOWDT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay (clock = 4000000)
#use rs232(baud=9600, Bits=8, Parity=N, xmit=PIN_C6, rcv=PIN_C7, stream=Module)
#use rs232(baud=9600, Bits=8, Parity=N, xmit=PIN_C0, rcv=PIN_C1, stream=PC)
int1 have_byte=false;
int8 val;
#int_rda
void int_rx(void) {
val=fgetc(Module);
have_byte=true;
}
void main()
{
int i=0;
...Configurations...
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
while(1)
{
if (kbhit(PC))
{
i=fgetc(PC);
fputc(i,module);
}
if (have_byte)
{
have_byte=false;
i=val;
fputc(i, PC);
}
}
}
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What happens?.
Best Wishes |
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dyeatman
Joined: 06 Sep 2003
Posts: 1933
Location: Norman, OK
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| Posted: Sun Jun 07, 2009 3:16 pm |
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For safety reasons shouldn't he add ERRORS to the USE statement?
_________________
Google and Forum Search are some of your best tools!!!! |
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Ttelmah
Guest
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| Posted: Mon Jun 08, 2009 4:01 am |
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Yes, though obviously only on the 'Module' stream.
It is always worth having this on hardware UARTs.
However, as the 'test' code stands, it shouldn't make a difference, _unless he is taking a long time, in the unpublished 'Configuration' section, that is not posted_. If so, it'd explain everything.....
Best Wishes |
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Mon Jun 08, 2009 9:14 am |
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What you mean | Ttelmah wrote: | | unless he is taking a long time, in the unpublished 'Configuration' section, that is not posted |
Well, in the “Configuration” section I am using long delays a couple of times… |
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