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pilar
Joined: 30 Jan 2008
Posts: 197
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| Where is the error in this loop? |
 Posted: Fri Sep 01, 2017 11:13 am |
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Hi,
I am using the interrupts of the uart to give me options to get out of the loop, but for more that I introduce the correct character I can not get out of the loop, my goal is if I enter any of the characters ('N', 'b', 'h' 'H', 'P') must be out of the loop ... someone can tell me what my mistake is ...
| Code: | #include <18F4620.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP,NOBROWNOUT
#use delay(clock=20MHz)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)// RS232 Estándar
char Keypress=' ';
#int_rda
void serial_isr() {
Keypress=0x00;
if(kbhit()){
Keypress=getc();
if(Keypress!=0x00){
putchar(keypress);
keypress=0x00;
}
}
}
void main() {
enable_interrupts(global);
enable_interrupts(int_rda);
printf("\r\n\Listen on RS232 \r\n");
do {
} while ((Keypress != 'N') && (Keypress != 'b') && (Keypress != 'h') && (Keypress != 'H') && (Keypress != 'P'));
printf("\r\n\The End\r\n");
while(1);
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Sep 01, 2017 11:51 am |
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| Quote: | void serial_isr() {
Keypress=0x00;
if(kbhit()){
Keypress=getc();
if(Keypress!=0x00){
putchar(keypress);
keypress=0x00;
}
}
} |
You get a key, such as 'N', but then you set 'Keypress' to 0x00 before
you leave the isr, as shown in bold above.
The PIC then exits the #int_rda function with 'Keypress' = 0x00, so
you stay in the do-while loop.
Try doing this instead:
| Code: | #int_rda
void serial_isr()
{
Keypress=getc();
putc(keypress);
} |
Also, you don't need kbhit(). If you are in the #int_rda function, it is
guaranteed that you have a kbhit. |
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pilar
Joined: 30 Jan 2008
Posts: 197
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| Posted: Fri Sep 01, 2017 1:58 pm |
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| Thank you! |
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ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
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| Posted: Fri Sep 01, 2017 3:18 pm |
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Hi,
A more important point is that to be a successful programmer you've got to learn to troubleshoot your own code! In this case, a print statement in your 'Do' loop showing the value of 'Keypress' would have given you the clues immediately to solve this issue yourself!
_________________
John
If it's worth doing, it's worth doing in real hardware! |
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