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Message |
Guest
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| how to check an input |
 Posted: Wed Jun 24, 2009 11:38 am |
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Hi, I am using PIC16f72 for my project.
I have set port_c as input and port_a digital output (through port_a I operate a Relay), initially port_a is "0xFF" and I want to compare the input of port_c with a desired value.
| Code: |
#include <16f72.h>
#USE DELAY( CLOCK=4000000 ) /* Using a 4 Mhz clock */
#FUSES XT,NOWDT,NOPROTECT,NOPUT
/* Use XT mode, No Watch Dog, No Code Protect, No Power-up Timer */
//PIC_C2=Low_Level
//PIN_C3=High_Level
#byte port_c=7 /* define the location of register port_b */
#byte port_a=5 /* define the location of register port_b */
#define ALL_DIGITAL 7
#define low 0xF7
void pump_on();
void pump_off();
main()
{
set_tris_a(0);
set_tris_c(1);
setup_adc_ports(ALL_DIGITAL);
port_a=0;
//port_c=0;
output_a(0xFF);
port_a=0xFF;
while(1)
{
if(port_c==low)
pump_off();
else
pump_on();
}
}
void pump_on()
{
port_a=0xFF;
}
void pump_off()
{
port_a=0x00;
}
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This is my current code but its not working. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 24, 2009 12:11 pm |
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This function takes a byte, in the form of a bitmask, as the parameter.
A '1' in the bitmask, means to make that bit in the port into an input pin.
A '0' means to make it be an output pin. There are typically 8 i/o pins
in a port.
Therefore, you are only setting Pin C0 as an input. All the rest of the
pins (C1-C7) are set as outputs.
Also, you are mixing direct port i/o operations with the built-in CCS
functions. Sometimes you do this:
But other times you do this:
You should choose one method and stick with it.
Also, you have not specified "#use fast_io" mode. This means the
compiler will operate in the default mode, which is called "Standard i/o"
mode. In this mode, the compiler sets the TRIS for you, whenever you
use the built-in i/o functions, such as output_a(), etc. This will conflict
with the set_tris_x() lines in your program. You'll set the TRIS to one
state, and the compiler will over-write that TRIS state when it executes
one of the i/o functions.
You need to use one method or the other.
1. Specify #use fast_io() for the specific ports, and then call the
set_tris_x() functions.
or,
2. Don't specify fast i/o mode. Leave the compiler in standard i/o mode.
Then use only the built-in i/o functions (of which there are many), and
let the compiler handle the TRIS for you automatically.
For a newbie, method #2 is much easier. |
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bharatwalia
Joined: 04 May 2009
Posts: 35
Location: India
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| Posted: Wed Jun 24, 2009 12:48 pm |
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Hi,thanks it worked.
After your suggestion I changed the code according to default settings,
but after sometime the program is hanging up.
Please go through the modified code, so that I can rectify it further.
| Code: |
#include <16f72.h>
#USE DELAY( CLOCK=4000000 ) /* Using a 4 Mhz clock */
#FUSES XT,NOWDT,NOPROTECT,NOPUT
/* Use XT mode, No Watch Dog, No Code Protect, No Power-up Timer */
//PIC_C2=Low_Level
//PIN_C3=High_Level
#byte port_c=7 /* define the location of register port_b */
#byte port_a=5 /* define the location of register port_b */
#define ALL_DIGITAL 7
#define low 0xF3
void pump_on();
void pump_off();
main()
{
//set_tris_a(0x00);
//set_tris_c(0xFF);
setup_adc_ports(ALL_DIGITAL);
//port_a=0;
//port_c=0;
output_a(0xFF);
input_c();
//port_a=0xFF;
while(1)
{
if(port_c==low)
pump_off();
else
pump_on();
}
}
void pump_on()
{
port_a=0xFF;
}
void pump_off()
{
port_a=0x00;
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 24, 2009 1:17 pm |
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You are still misunderstanding how to use the functions.
This statement is incorrect. You need to either load a variable with
the result of the input_c() function, or you need to compare the result
to some other expression. Don't use "input_c()" all by itself on a line.
One example of correct usage:
| Code: |
int8 result;
result = input_c();
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| Quote: |
while(1)
{
if(port_c==low)
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Here you are still using direct register i/o. If you want to read Port C
continuously inside the loop (and do it in standard i/o mode), then use
the input_c() function. Example:
| Code: |
while(1)
{
if(input_c() == low) |
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Guest
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| Posted: Wed Jun 24, 2009 1:54 pm |
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Further rectified it is working but the program is hanging up after sometime.
| Code: |
#include <16f72.h>
#USE DELAY( CLOCK=4000000 ) /* Using a 4 Mhz clock */
#FUSES XT,NOWDT,NOPROTECT,NOPUT
/* Use XT mode, No Watch Dog, No Code Protect, No Power-up Timer */
//PIC_C2=Low_Level
//PIN_C3=High_Level
#byte port_c=7 /* define the location of register port_b */
#byte port_a=5 /* define the location of register port_b */
#define ALL_DIGITAL 7
#define low 0xF3
void pump_on();
void pump_off();
main()
{
setup_adc_ports(ALL_DIGITAL);
while(1)
{
if(input_c()==low)
pump_off();
else
pump_on();
}
}
void pump_on()
{
output_a(0xFF);
}
void pump_off()
{
output_a(0x00);
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 24, 2009 1:59 pm |
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What is connected to the pins on Port C ?
Post a detailed explanation of the circuits on each pin of Port C. |
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bharatwalia
Joined: 04 May 2009
Posts: 35
Location: India
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| Posted: Thu Jun 25, 2009 2:23 pm |
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| Hi, thanks a lot. It worked. |
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