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piire
Joined: 04 Mar 2009
Posts: 19
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| digital inputs pic16f877a |
 Posted: Wed Mar 04, 2009 2:06 pm |
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hi there I'm new to this forums so just like to say hello to everyone.
I'm new to pic programming and would like some guidance.
I have a digital sensor, which has one output. I have connected it to a digital i/o pin on the PIC and then the PIC is connected to the max232 and then to the serial port of my computer. This is the code that I have for the PIC but it doesn't seem to work. What I want the code to do is to get the reading from the sensor and display it on the computer.
| Code: |
#include <16F877A.H>
#use delay (clock=4000000)
#use rs232(baud=2400,xmit=PIN_E0,rcv=PIN_E1)
unsigned int32 read1;
int8 sem;
//
// Define which timer to use and minor_cycle for RTOS
//
#use rtos(timer=1, minor_cycle=100ms)
// Declare TASK "Get_Reading" - called every 10ms
#task(rate=2s, max=100ms)
void Get_Reading()
{
rtos_wait(sem); // decrement semaphore
read1 = input(PIN_C0);
rtos_signal(sem); // increment semaphore
}
//
// Declare TASK "To_RS232" - called every millisecond
//
#task(rate=2s, max=100ms)
void To_RS232()
{
rtos_wait(sem); // Decrement semaphore
printf("Reading = %LumV\n\r",read1); // Send to RS232
rtos_signal(sem); // Increment semaphore
}
//
// Start of MAIN program
//
void main()
{
set_tris_c(0xFF); // PORT C all inputs
delay_us(10);
sem = 1; // Semaphore is 1
rtos_run(); // Start RTOS
} |
thanks for your help
piire! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Mar 04, 2009 2:47 pm |
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I suggest that you start with a simple program that doesn't use the RTOS.
Make that program work first. Here's an example:
| Code: | #include <16F877A.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=2400,xmit=PIN_E0,rcv=PIN_E1)
//===================================
void main()
{
while(1)
{
if(input(PIN_C0)) // Read the switch pin.
putc('1'); // Display the state of the pin.
else
putc('0');
delay_ms(100);
}
} |
Make sure that pin C0 has a pull-up resistor on it. You can use 4.7K or
10K. |
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Sydney
Joined: 13 Feb 2009
Posts: 71
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| Posted: Wed Mar 04, 2009 3:22 pm |
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| Agree with PCM, and you seem to be overlooking the fact that input(PIN_C0); is only ever going to return 0 or 1, what sensor is it? |
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