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Joris H
Joined: 24 Sep 2003 Posts: 14
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RS232-PIC is locking up |
Posted: Wed Sep 24, 2003 8:22 pm |
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Hi,
In my project I use a PIC16f877-20/P. I try to communicate with a GSM-module. When I run the code then the LCD display: -AT+CMGR= xxx
(this is code that I send) after that the PIC is locking up. The displayed time is stopped.
I tryed to put the " printf(lcd_putc,"\%S",receved_from_modem);"line directly in the "get_string(receved_from_modem,int max)" and then I got the complete responce from the module in one long string. I tryed other AT-Commands with the same result.
Why is the PIC locking up?
Please HELP
CCS: 3.091
some code:
#include <16F877.h>
#use delay(clock=20000000)
#fuses HS,NOWDT,NOBROWNOUT,NOLVP,NOPROTECT
#use fixed_io(c_outputs=pin_C6)
#use rs232(baud=9600,parity=n,bits=8,xmit=PIN_C6,rcv=PIN_C7)
#int_RDA
RDA_isr() {
get_string(receved_from_modem,160);
bit_set(ModemFlag,RecMess);
}
void main() {
int b;
rtc_init();
lcd_init();
init_ext_eeprom();
enable_interrupts(INT_RDA);
enable_interrupts(global);
strcpy(OK, "OK");
do
{Display_MainMenu();}
while(TRUE);
}
void get_string(receved_from_modem,int max) {
int len;
char c;
max--;
len=0;
do {
c=getc();
if(c==0x0A ||c==0x0D) { //DEL first CR and LF
if(len<2) {
len--;
c='z';
}
} else if ((c>=' ')&&(c<='~'))
if(len<max) {
len=len+1;
receved_from_modem[len]=c;
}
} while(c!=0x0A ); //(c!=LF)||(c!=CR)||
receved_from_modem[len]=0;
//printf(lcd_putc,"\fyy%S",receved_from_modem);
}
run_manual()
{lcd_putc("\fGSM ");
disable_interrupts(global);
printf("AT+CMGR=1\n");
delay_us( 1000 );
enable_interrupts(INT_RDA);
enable_interrupts(global);
do {
Display_Time(); //display the real time hh:mm:ss
if (bit_test(ModemFlag,RecMess))
{bit_clear(ModemFlag,RecMess);
printf(lcd_putc,"\%S",receved_from_modem);
printf(lcd_putc," xxx ");}
}
while (TRUE); |
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Neutone
Joined: 08 Sep 2003 Posts: 839 Location: Houston
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Posted: Thu Sep 25, 2003 7:34 am |
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You are not handeling errors in your USART. If you recieve more than a single byte while performing a task like formatting a string the recieve buffer will over run.
Code: |
#use rs232(baud=9600,parity=n,bits=8,xmit=PIN_C6,rcv=PIN_C7)
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Try this change.
Code: |
#use rs232(baud=9600,parity=n,bits=8,xmit=PIN_C6,rcv=PIN_C7,errors)
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Humberto
Joined: 08 Sep 2003 Posts: 1215 Location: Buenos Aires, La Reina del Plata
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Posted: Thu Sep 25, 2003 9:30 am |
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Joris
Try this way, don't tested but it will work. Just to show how I will do it.
Let us know if this aproach is usefull for you.
Best wishes,
Humberto
Code: |
#include <16F877.h>
#use delay(clock=20000000)
#fuses HS,NOWDT,NOBROWNOUT,NOLVP,NOPROTECT
//#use fixed_io(c_outputs=pin_C6) // >>> Not needed
#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7, ERRORS)
// Define a buffer to store incoming chars
#define BUFFER_SIZE 20 // Adjust this value
#define HeaderString 'x' // Where x = Fisrt char expected in the string
receved_from_modem[BUFFER_SIZE];
//#int_RDA
//RDA_isr() {
//get_string(receved_from_modem,160); Not recommend to call a function inside the ISR.
//bit_set(ModemFlag,RecMess);
//}
#int_RDA
RDA_isr()
{
char c;
c=getc();
if(c==HeaderString)
{
len = 0;
receved_from_modem[len] = c;
len++;
}
else if ((c>=' ')&&(c<='~'))
{
receved_from_modem[len] = c;
len++;
}
if(c==0x0A ||c==0x0D) // I gues End Of String
{
bit_set(ModemFlag,RecMess); // All OK
}
if(len >= BUFFER_SIZE)
{
bit_set(ModemFlag,RecErr); // Something wrong !!
disable_interrupts(INT_RDA); // Get out & ovoid reentrance
}
}
void main() {
int b;
rtc_init();
lcd_init();
init_ext_eeprom();
enable_interrupts(INT_RDA);
enable_interrupts(global);
strcpy(OK, "OK");
while(1)
{
Display_MainMenu();
run_manual()
lcd_putc("\fGSM ");
disable_interrupts(global);
printf("AT+CMGR=1\n");
delay_us( 1000 );
// enable_interrupts(INT_RDA);
enable_interrupts(global);
Display_Time(); //display the real time hh:mm:ss
if (bit_test(ModemFlag,RecMess))
{
bit_clear(ModemFlag,RecMess);
printf(lcd_putc,"\%S",receved_from_modem);
printf(lcd_putc," xxx ");}
}
} // while
} // Main
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Joris H
Joined: 24 Sep 2003 Posts: 14
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RS232 |
Posted: Sun Sep 28, 2003 11:49 am |
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Thanks for the help
I reworked a bit the sample code send by Humberto
For your info here the code for the interrupt
RDA_isr() {
int len;
char c;
do{
c=getc();
if(c==LF ) //DEL first CR and LF from the mess.
{if (len<=2)
Thanks again
Joris
{len=0;
c=0;
}}
else if (c>=' '&& c<='~')
{
receved_from_modem[len]=c;
len++;
len_mess=len; //find the # of caracters
}
if(c==LF ); //(c!=LF)||(c!=CR)|| //End of mess.
{
bit_set(ModemFlag,RecMess);
receved_from_modem[len]=0;
disable_interrupts(INT_RDA); //get out of interrupt
}
if (len>=BUFFER_SIZE) //someting went wrong
{
bit_set(ModemFlag,RecErr);
disable_interrupts(INT_RDA); //get out
}}
while (c!=LF );
len=0;
} |
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densimitre
Joined: 21 Dec 2004 Posts: 45
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Posted: Tue Oct 18, 2005 7:46 pm |
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Hi
If I have a 16F877 in asincronous and full duplex mode, when I send a "AT <CR>" to modem, what happend?
1.- The modem answer after "A" with a "A" but PIC donīt listen up to finish send all "AT <CR>" comand???
2.- The PIC read that "A" and after send the "T" and so on?..
How can i prevent lost data?
Thank you very much |
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