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how to output a 16bit value to two 8 bit ports

 
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brood



Joined: 23 Jan 2007
Posts: 12

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how to output a 16bit value to two 8 bit ports
PostPosted: Tue Jan 23, 2007 8:23 am     Reply with quote

Hi

I would like to know if its possible to output a 16bit value to two 8 bit ports and how to do it. The pic that I'm using is: pic16f917

My aim is to control 16 led's connected to port A and port B with a single hex value. I was successful with controlling port A with a single hex value.

here is my setup code with two code arrays:

#include <16F917>
#fuses INTRC_IO,NOPROTECT,NOWDT,PUT
#use delay(clock=8000000)
#use standard_io(a)
#use standard_io(b)
#use standard_io(c)
#use standard_io(d)
#case

const unsigned int A[10] = {0xFFF8, 0xFFFC, 0x0186, 0x0183, 0x0181, 0x0181, 0x0183, 0x0186, 0xFFFC, 0xFFF8}; //A

const unsigned int a[5] = {0x7C, 0x12, 0x11, 0x12, 0x7C}; //a

void main()
{
setup_lcd(LCD_DISABLED); // disables lcd display to access digital outputs
for (;;)
{
delay_ms(1000);
output_a(a[0]); // 1st line of a
}

}
SherpaDoug



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

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PostPosted: Tue Jan 23, 2007 8:29 am     Reply with quote

How about using make8() to split the bytes, and dealing with each byte seperately?
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brood



Joined: 23 Jan 2007
Posts: 12

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PostPosted: Tue Jan 23, 2007 9:01 am     Reply with quote

I think that might just do the trick

Thank you very much Wink
treitmey



Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA

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PostPosted: Tue Jan 23, 2007 9:24 am     Reply with quote

you could also try fastio.
set the tris.
use a #byte to define where it is placed.
((or overlayed, how ever you want to think of it))
It uses the location and the next. ie: portA and port B
Code:
#use fast_io(A)
#use fast_io(B)
struct PINS
{
   int16 leds;
};
struct PINS my;
#byte my= 0x05   //note: no semicolin    0x05=A0 on a 16F877

my.leds=0xABCD;

I chopped apart my code... I hope it still works

Don't forget to set tris A and B it isn't shown in this code.
mrpicing



Joined: 22 Oct 2005
Posts: 20

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an other way
PostPosted: Sun Jan 28, 2007 11:10 am     Reply with quote

you can do it as below.

Code:
unsigned long port16;  //it will accupy two bytes. byte 5, byte 6
#byte port16=5  /* porta address. check porta adress form device data sheet*/
/* other code*/

port16= 0xffff;  //put ur data as this
/* other code*/
brood



Joined: 23 Jan 2007
Posts: 12

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PostPosted: Sun Jan 28, 2007 3:30 pm     Reply with quote

Thank you for all the replies it solved lots of problems that I had. Everything is up and running now. I used make8() in the end and passed two 8bit values to my output function.

Wink
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