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mob1182
Joined: 03 Mar 2016
Posts: 28
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| input.c acting weird, can it not be used for software UART? |
 Posted: Thu Jul 28, 2016 5:23 pm |
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Hi I am trying to use input.c to read a max number of chars for the user but I am having a problem getting it to work correctly. When I use fgets, everything works fine but when I use get_string I only receive every other char and for some reason it prints an extra output.
CCS PCH C Compiler, Version 5.055
| Code: |
#include <18F4685.h>
#DEVICE ADC=10;
#FUSES INTRC,NOWDT,NOMCLR,NOCPD,NOBROWNOUT,NOIESO,NOFCMEN,NOLVP,PUT
#use delay(internal=16000000)
#use fast_io(C)
#USE RS232(BAUD=9600, parity=N, XMIT=PIN_C3, RCV=PIN_C4, bits=8, TIMEOUT=10000, STREAM = pc, ERRORS)
#include <string.h>
#include <stdlib.h>
#include "input.c"
char user_string[50];
//=============================================================================
void main()
{
SET_TRIS_C(0X51); //0101 0001
delay_ms(500);
while(true)
{
int i;
for(i=0; i<50; i++)
user_string[i] = NULL;
fprintf(pc, "\r\nEnter(fprintf):\r\n");
fgets(user_string, pc);
fprintf(pc, "\r\nRCV: %s\r\n", user_string);
for(i=0; i<50; i++)
user_string[i] = NULL;
fprintf(pc, "\r\nEnter(input.c):\r\n");
get_string(user_string, 50);
fprintf(pc, "\r\nRCV: %s\r\n", user_string);
}
} |
When I enter "abcdefghijklmnop" (without the quotes) in a terminal program(Tera Term), the output I receive is as follows:
| Quote: |
Enter(fprintf):
RCV: abcdefghijklmnop
Enter(input.c):
acegikmo <-----------where is this coming from?
RCV: acegikmo
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As you can see fgets works fine and so does fprintf, so comms are setup correctly. But, get_string has bad results.
Thanks in advance to anyone who can shed some light on this. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Jul 28, 2016 5:54 pm |
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You're using a soft UART, and get_string() echoes back the typed
character to the terminal. So, the PIC cannot receive every 2nd char
because it's spending that time outputting the previous char to TeraTerm.
A soft UART (of the type that CCS uses) consumes the entire time of the
processor. It can either send or receive. It can't do both at the same
time. |
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mob1182
Joined: 03 Mar 2016
Posts: 28
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| Posted: Thu Jul 28, 2016 6:10 pm |
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Thanks for the quick response PCM! 
I didn't even see the InputPutc(c);  That's what happens when you stare at a monitor for 12 hrs straight.
When I get back to the lab tomorrow I will try it with commenting that line out.
Is it safe to assume this will work?
Of course I would create a copy of the file first as to not modify the original, or just copy what I need. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Jul 28, 2016 6:49 pm |
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| Yes, delete that line and it won't echo the char. |
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