Button.c

[honeytree]

I ran the button.c code as listed on the board, yet I do not receive any output to screen as suggested. How is the RS232 being used?

--------------------------------------------------------
#include <16F877.H>
#use delay(clock = 4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

// These are the "Bvar" variables.
int button1 = 0; // For the button on pin A4
int button2 = 0; // For the button on pin B0

#include "button.c"

/* Function parameters:

button(pin, DownState, Delay, Rate, BVar, Action)

Returns: The value of the Action variable (normally
set = 1) is returned when the button is
pressed. When the button isn't pressed,
*/ the opposite value is returned (normally 0).

void main()
{
printf("\n\rStart: ");

set_tris_a(0x10); // Set Pin A4 as input
set_tris_b(0x01); // Set Pin B0 as input


// When button on RB0 is pressed, "B" is displayed on the
// LCD. When the RA4 button is pressed, "A"
// is displayed. If you hold the buttons down for more
// than 1/2 second, they will auto-repeat 10 times per
// second.

while(1)
{
if(button(PIN_B0, 0, 50, 10, button2, 1))
printf("B");

if(button(PIN_A4, 0, 50, 10, button1, 1))
printf("A");

// You must use a delay statement in the loop.
// A good value to use is 10 ms.
delay_ms(10);
}

}
---------------------------------
// button.c file
//******************************************************

/* Pin: such as PIN_B0.
Downstate:
This is the logic level of the button when it's pressed.
For a circuit with a Normally-Open switch and a pull-up
resistor, this parameter will be 0.

Delay:
This is the initial delay before auto-repeat begins.
Example: A Delay value of 50 means a 500 ms auto-repeat
delay.

Rate:
This is the auto-repeat interval.
Example: A Rate value of 10 gives a 100 ms interval,
which means an auto-repeat rate of 10 keys per second.

Bvar:
This an 8-bit variable that must be declared in the main
// program, and it must be initialized to zero. There must
// be a separate variable for each button that you use.
// Example: Declare the variable for pin B0 as int8 B0 = 0;
// See the demo program for more examples. Note that Bvar
// is a "reference variable" (it has a "&" in front of it).
// This is intentional. It's done so the button function
// can directly access the Bvar variable which is declared
// outside the function, without having to pass a pointer
// to it. This keeps the function interface simple.
//====================================

// Action:
// This is the value that's returned when the button is
// pressed. Normally you set this = 1.

// Return value:
// When the button is pressed, the value of the Action
// parameter will be returned. When the button is not
// pressed, the opposite value will be returned.
// Normally, you set the Action parameter = 1, and so
// if the button is pressed, the function will return 1.
// If it's not pressed, it will return 0. So you just
// poll the function every 10 ms in a loop, and check the
// return value with an if() statement. If it's non-zero
// then the button is pressed and you can take appropriate
// action.
*/


//=====================================
// The following macro is used by the Button function.
#define read_bit_var(x) bit_test(*(int8 *)(x >> 3), x & 7)


//=====================================
int8 button(int16 pin, int8 downstate, int8 delay,
int8 rate, int8 &BVar, int8 action)
{
int8 pin_value;

// Read the button pin.
pin_value = read_bit_var(pin);

// Check if the button is pressed. It's pressed if the
// pin value is the same as the "downstate". If it's not
// pressed, then zero the Bvar and return "Not pressed".
if(pin_value != downstate)
{
Bvar = 0;
return(!action);
}

// The button is pressed. Check to see if it's a new
// keypress. We can tell if it's a new keypress by
// checking if BVar = 0. If so, load the counter with
// the initial auto-repeat delay and return "Pressed".
// (If the delay has been set to 0, then load a non-zero
// value to allow the function to operate properly).
if(Bvar == 0)
{
if(delay == 0)
Bvar = 255;
else
Bvar = delay;

return(action);
}

// Decrement the auto-repeat counter.
Bvar--;

// Check if we just counted down to 0. If so, then load
// the counter with the auto-repeat interval and return
// "Pressed". If the delay is set to 0 or 255, it means
// that auto-repeat is disabled, so fall through and
// return "Not Pressed".
if(BVar == 0)
{
BVar = rate;

if((delay != 0) && (delay != 255))
return(action);
}

// If the counter is positive, then it means an auto-repeat
// is still pending, so return "Not Pressed".
return(!action);

}

[PCM programmer]

You don't have to keep posting the code over and over again.
I posted that code for people who had previously used PicBasicPro
and know how to use it, and just want a quick way to move over
to CCS.

I suggest you start with a simple "Hello World" program, that
just displays text on a terminal window in a PC. Example:

[honeytree]

Thank you for your help.