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Problem sending command from 16F877 to GPRS modem

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WildLife

Joined: 08 Jun 2011
Posts: 2

Problem sending command from 16F877 to GPRS modem

Posted: Wed Jun 08, 2011 8:21 pm

Hi guys, first post here Smile

I'm trying to communicate my 16F877 with a GPRS modem (ADH8066 with the evaluation board from sparkfun).

I'm using the following code:

Code:

#include <16F877A.h>

#fuses HS,NOWDT,NOLVP,PUT,NOPROTECT,NOBROWNOUT,NOWRT

#use delay(clock=20000000)
#use rs232(baud=115200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,stream=GPRS,ERRORS)

#define BUFFER_SIZE 32
BYTE buffer[BUFFER_SIZE];
BYTE next_in = 0;
BYTE next_out = 0;

#define bkbhit (next_in!=next_out)
char cmd_str[20];

byte bgetc()
{
byte c;

while(!bkbhit) ;
c=buffer[next_out];
next_out=(next_out+1) % BUFFER_SIZE;
return(c);
}

#int_rda
void serial_received()
{
int t;

buffer[next_in]=getc();
t=next_in;
next_in=(next_in+1) % BUFFER_SIZE;
if(next_in==next_out)
next_in=t; // Buffer full !!
}

void init()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_spi(FALSE);
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);
enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);
output_high(GSM_ONKEY);
output_high(GSM_CTS);
output_high(GSM_DSR);
output_low(GSM_LED);
}

int startGSM()
{
delay_ms(200);
output_high(GSM_ONKEY);
output_high(GSM_CTS);
output_high(GSM_DSR);
delay_ms(500);
output_low(GSM_ONKEY);
delay_ms(2000);
output_high(GSM_ONKEY);
delay_ms(300);
output_low(GSM_CTS);
output_low(GSM_DSR);
delay_ms(4000);

//ler ready!

return 1;
}

void testePrintGSM()
{
delay_ms(1000);
fprintf(GPRS,"AT\n");
delay_ms(1000);
}

void main()
{
int8 cont = 0;

unsigned char a;

init();

timeout(5);

output_high(GSM_LED);

startGSM();

output_low(GSM_LED);

timeout(15);

while(true)
{
// Searches for 'ady' from the word Ready witch means modem has reset
if (bkbhit)
{
a = bgetc();
}
if (a == 'a')
{
a = bgetc();
if (a == 'd')
{
a = bgetc();
if (a == 'y')
{
output_high(GSM_LED);

timeout(3);

testePrintGSM();
}
}
}

// Searches for OK, reply from the command fprintf(GRPS,"AT\n")
else if (a == 'O')
{
a = bgetc();
if (a == 'K')
{
output_low(GSM_LED);
}
}

delay_ms(50);
}

Sorry for the big code, anyways, I'm able to read from the modem the "Ready" reply, but I can't read the OK reply, so I assume I'm not being able to send the "AT\n" command. Any ideas?

BTW I've already tried fprintf, putc, and so on, with no luck :/

Thanks,

WildLife

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Wed Jun 08, 2011 9:13 pm

Quote:

fprintf(GPRS,"AT\n");

Your final character is a newline, but the modem expects a carriage
return, which is a \r.

WildLife

Joined: 08 Jun 2011
Posts: 2

Posted: Thu Jun 09, 2011 8:59 am

PCM programmer wrote:

Quote:

fprintf(GPRS,"AT\n");

Your final character is a newline, but the modem expects a carriage
return, which is a \r.

That might have saved me some hassle in the future, but still it isn't working :(

Any other thoughts?

Thanks

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