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get string from RS232

 
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filjoa



Joined: 04 May 2008
Posts: 260

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get string from RS232
PostPosted: Sun Oct 03, 2010 6:54 pm     Reply with quote
Hi

I use 241024", 1ยบ 4bits is to control a servo and last 4bits is to control on my program function "get_long()" and then I give this "10her...

For last 4 bits I think this solution:
Quote:

aux= get_long();

sp = 1000 + (aux >> 4);

and my result is 2024 write?

But now to make same operation but with first 4 bits how I can make? Someone have an idea?

best regards

Last edited by filjoa on Tue Oct 05, 2010 6:08 am; edited 1 time in total
SherpaDoug



Joined: 07 Sep 2003
Posts: 1640
Location: Cape Cod Mass USA

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PostPosted: Mon Oct 04, 2010 6:26 am     Reply with quote
It depends on how sp and aux are declared.

Give us a small compilable program so we can see what we are working with.
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filjoa



Joined: 04 May 2008
Posts: 260

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PostPosted: Mon Oct 04, 2010 12:55 pm     Reply with quote
hi

I have problems and I thinks it's because aux, sp and dr is an LONG (16bits).

So, now on hyperterminal I write some like this "s1024d1024\n". I need identify this two numbers (my range is s0000d0000 to s1024d1024) and put this on my variable "sp" and "dr".
Code:

char string[11], sp[4], dr[4];
int8 i;

while(1)
{

gets(string);

for(i=0;i<=3;i++)
   {
   sp[i]=string[i+1];
   }
for(i=0;i<=3;i++)
   {
   dr[i]=string[i+5];
   }

SPEED = atol(sp);
STEERING = atol(dr);

}

Is correct I have my code like this?

best regards
filjoa



Joined: 04 May 2008
Posts: 260

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PostPosted: Tue Oct 05, 2010 6:08 am     Reply with quote
hi

when I use "gets(string)" function my PIC stop work, why?

I include stdlib.h and active INT_RDA...

I forget anything?

PS: my PIC is an 16F628A at 20Mhz.

best regards
Ttelmah



Joined: 11 Mar 2010
Posts: 19476

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PostPosted: Tue Oct 05, 2010 12:25 pm     Reply with quote
You can't use 'gets', with interrupt driven RS232.

gets, expects to sit and wait for an entire string. If you put it inside an interrupt receive routine, you 'throw away' the point of having interrupt driven receive, locking the program till the string arrives. Yetch.
Put it outside the interrupt, and the PIC will hang forever, since characters will never become available to this routine....

The solution, is to add a single flag to the interrupt receive routine. Have this global, and set it when a carriage return is seen. Then in your main code do your other tasks, _till this flag is set_. Once it is, clear it, and use the bgetc routine, to get the available characters, and assemble the string.

Best Wishes
filjoa



Joined: 04 May 2008
Posts: 260

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PostPosted: Wed Oct 06, 2010 9:17 am     Reply with quote
Hi

I understand idea and I try make it, but result don't the best....

My program:
Code:

#include <18F252.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP,BROWNOUT
#use delay(clock=20000000)
#use rs232(baud=115200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)

#build(reset=0x200)
#build(interrupt=0x208)
#org 0x0000,0x01ff
void bootloader() {
#asm
  nop
#endasm
} // Reserve space for the bootloader

#include <stdlib.h>

// ### VARIAVEIS GLOBAIS ###
int16 SPEED = 1600;
int16 STEERING = 1400;
int1 data_available = FALSE;
char c;

// ### READ RS232 ###
#int_rda
void rda_isr(void)
{
c = getc();
data_available = TRUE;
}

void TIMER1_isr(void)
{
output_high(PIN_B7);
delay_us(SPEED);     
output_low(PIN_B7);
}

#int_TIMER2           
void TIMER2isr(void)
{
output_high(PIN_B6);
delay_us(STEERING);     
output_low(PIN_B6);
}

void read_str()
{
int8 i=0;
char string[11], sp[4], dr[4];

while (c != '#'); 
data_available = FALSE;

do {
   while (data_available == FALSE);
   data_available = FALSE;
   string[i]=c;
   i++;
} while (c != 13);

printf("string: %s\n\r",string);

for (i=0; i<=3; i++)
{
sp[i]=string[i+1];
}
for (i=0;i<=3;i++)
{
dr[i]=string[i+6];
}

printf("speed_t: %s\n\r", sp);
printf("steerin_t_b: %s\n\r",dr);

SPEED = atol(sp);
STEERING = atol(dr);

printf("speed_b: %lu\n\r", SPEED);
printf("steering_b: %lu\n\r",STEERING);

SPEED=1100 + SPEED; // gama de 1200 - 1600 - 2000

STEERING=900 + STEERING; // gama de 1000 - 1400 - 2000


printf("speed: %lu\n\r", SPEED);
printf("steering: %lu\n\r",STEERING);

}

void main()
{

enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);

setup_timer_1(T1_INTERNAL | T1_DIV_BY_1); 
enable_interrupts(INT_TIMER1);

setup_timer_2(T2_DIV_BY_16,243,16);     
enable_interrupts(INT_TIMER2);

while(1)
{

read_str();

}
}

When I put on hyperminal this "#s1000d1000\n" the return is:
Quote:

1000100061000d1000
speed_t: 100010006
steerin_t_b: 10006
speed_b: 39528
steering_b: 10002
speed: 40628
steering: 10902

Someone know why?

best regards
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