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newbie333 Guest
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weird occurance dont understand |
Posted: Tue Sep 09, 2008 8:54 am |
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Hello
I have encountered a problem which i really dont understand please help
below is a code snippet 1 with its associated header file.
First is a main.h file that contains a some simple micros that set TRIS directions and set them high of low. In this instance I am using or's and ands to turn bits high and low.
main1.h file
Code: |
/**********************************************************/
/* */
/* PROJECT SCOPE SECTION */
/* */
/**********************************************************/
/* */
/* CONSTANTS/MACROS (#Def's) AVAILABLE TO WHOLE PROJECT */
/* */
/**********************************************************/
#define bitTest(var,bitNo) ((var & (1<<bitNo)) != 0)
#define bitSet(var,bitNo) (var |= (1<<bitNo))
#define bitClear(var,bitNo) (var &= ~(1<<bitNo))
/************************************************************/
/* */
/* DEFINES (#Def's) AVAILABLE TO FILE */
/* */
/************************************************************/
#define BIT0 0x01
#define BIT1 0x02
#define BIT2 0x04
#define BIT3 0x08
#define BIT4 0x10
#define BIT5 0x20
#define BIT6 0x40
#define BIT7 0x80
#define BUTTON1_B BIT0
#define BUTTON1_P PORTB
#define BUTTON1_D INPUT
#define BUTTON1_SET_TRIS (TRISB&= ~(BUTTON1_B & BUTTON1_D))
#define SET_BUTTON1 (BUTTON1_P |= BUTTON1_B)
#define CLR_BUTTON1 (BUTTON1_P &= ~BUTTON1_B)
#define BUTTON1_PRESSED (BUTTON1_P & BUTTON1_B)
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main1.c contains a main entry file that sets the tris directions only
Code: |
***********************************************************
*
*
*
************************************************************/
#define _MAIN1_C_
/******************************************************
; Include files. Application dependent
******************************************************/
#include<18F45K20.h>
#fuses H4 /* Config bit. HSPLL x4 enabled */
#fuses CCP2B3 /* Config bit. Multiplex PWM pins to use B3 */
//#fuses NODEBUG
#DEVICE ADC=10 // CCS why of setting adc to 10 bit
//#DEVICE ICD=FALSE
#priority int_timer0,int_timer3 /* CCS why of setting up interrupt priorities */
#use delay(clock=64000000) /* CCS Used for inbuilt functions. used for delay_X() functions */
#use rs232(baud = 115000,xmit=PIN_C6,rcv=PIN_c7) /* CCS Used for inbuilt functions. used for printf functions */
#include "PIC18F45K20_registers.h"
#include "main3.h"
#include "tdef.h"
void main()
{
//TRISB = 0x00;
BUTTON1_SET_TRIS;
while(1)
{
}
}
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Now here is the problem. In the main.c file you can see that if i set the TRISB = 0x00; then use the macro BUTTON1_SET_TRIS;
the trisb1 should go high and the reset should go low. however it does not do this. the macro does not seem to have any affect. Why is this.
please note:- If i declare the BUTTON1_SET_TRIS to be TRISB1 = 1; this seems to work.
I would like to understand why as, in that If before I set any TRIstates, i put TRISB = 0x00; then use these macros with ors and ands it does not seem to work. if I dont have this TRISB = 0x00; in the beginning then the BUTTON1_SET_TRIS seems to work.
regards |
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newbie333 Guest
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Posted: Tue Sep 09, 2008 8:58 am |
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SOrry forgot to mention. I am using CCS version 4.077 amd mplab 8.10. |
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Guest
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Posted: Tue Sep 09, 2008 9:30 am |
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This is simple enough an example - look in the lst file and see if the compiler is doing what you ask. You might simplify the macro some to make it easier to see what the compiler is doing.
HTH - Steve H. |
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newbie333 Guest
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Posted: Tue Sep 09, 2008 9:57 am |
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You read my mind steve.
the disassembly show me
Snippet 1 of disassembly....
In the code below is the disassembly with BUTTON1_SET_TRIS defined as
#define BUTTON1_SET_TRIS (TRISB1 = 1)
Code: |
0004 6AF8 CLRF 0xff8, ACCESS
0006 9ED0 BCF 0xfd0, 0x7, ACCESS
0008 6AEA CLRF 0xfea, ACCESS
000A 6AE9 CLRF 0xfe9, ACCESS
000C 86B8 BSF 0xfb8, 0x3, ACCESS
000E 0E8A MOVLW 0x8a
0010 6EAF MOVWF 0xfaf, ACCESS
0012 0E00 MOVLW 0
0014 6EB0 MOVWF 0xfb0, ACCESS
0016 0EA6 MOVLW 0xa6
0018 6EAC MOVWF 0xfac, ACCESS
001A 0E90 MOVLW 0x90
001C 6EAB MOVWF 0xfab, ACCESS
001E 507E MOVF 0xf7e, W, ACCESS
0020 0BE0 ANDLW 0xe0
0022 6E7E MOVWF 0xf7e, ACCESS
0024 98C1 BCF 0xfc1, 0x4, ACCESS
0026 9AC1 BCF 0xfc1, 0x5, ACCESS
0028 0E00 MOVLW 0
002A 6E7F MOVWF 0xf7f, ACCESS
002C 9A79 BCF 0xf79, 0x5, ACCESS
002E 9879 BCF 0xf79, 0x4, ACCESS
0030 6A7B CLRF 0xf7b, ACCESS
0032 6A7A CLRF 0xf7a, ACCESS
32: //TRISB = 0x00;
33:
34: BUTTON1_SET_TRIS;
0034 9293 BCF 0xf93, 0x1, ACCESS
35:
36: while(1)
37: {
38: }
0036 D7FF BRA 0x36
39:
0038 0003 SLEEP
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The above code produces expected code:: (line 0034)
Snippet 2 of disassembly....
In the code below is the disassembly with BUTTON1_SET_TRIS defined as
#define BUTTON1_SET_TRIS (TRISB&= ~(BUTTON1_B & BUTTON1_D))
Code: |
30: void main()
31: {
0004 6AF8 CLRF 0xff8, ACCESS
0006 9ED0 BCF 0xfd0, 0x7, ACCESS
0008 6AEA CLRF 0xfea, ACCESS
000A 6AE9 CLRF 0xfe9, ACCESS
000C 86B8 BSF 0xfb8, 0x3, ACCESS
000E 0E8A MOVLW 0x8a
0010 6EAF MOVWF 0xfaf, ACCESS
0012 0E00 MOVLW 0
0014 6EB0 MOVWF 0xfb0, ACCESS
0016 0EA6 MOVLW 0xa6
0018 6EAC MOVWF 0xfac, ACCESS
001A 0E90 MOVLW 0x90
001C 6EAB MOVWF 0xfab, ACCESS
001E 507E MOVF 0xf7e, W, ACCESS
0020 0BE0 ANDLW 0xe0
0022 6E7E MOVWF 0xf7e, ACCESS
0024 98C1 BCF 0xfc1, 0x4, ACCESS
0026 9AC1 BCF 0xfc1, 0x5, ACCESS
0028 0E00 MOVLW 0
002A 6E7F MOVWF 0xf7f, ACCESS
002C 9A79 BCF 0xf79, 0x5, ACCESS
002E 9879 BCF 0xf79, 0x4, ACCESS
0030 6A7B CLRF 0xf7b, ACCESS
0032 6A7A CLRF 0xf7a, ACCESS
32: //TRISB = 0x00;
33:
34: BUTTON1_SET_TRIS;
35:
36: while(1)
37: {
38: }
0034 D7FF BRA 0x34
39:
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as you can see nothing appears for the
#define BUTTON1_SET_TRIS (TRISB&= ~(BUTTON1_B & BUTTON1_D))
why?? |
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Ttelmah Guest
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Posted: Tue Sep 09, 2008 10:01 am |
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As shown, the macros, don't make sense. If you expand your line as posted, you get:
BUTTON1_SET_TRIS =>
Which expands as:
TRISB = TRISB & (~(0x1 & INPUT))
Input what?.
If you '&' something, you can only get a bit set in the output, if there is a '1' in the same place on both sides of the &. So, if you start with TRISB=0, you can never get a '1' in any bit of the result from this operation, whatever appears on the other side. Exactly what you are seeing....
Best Wishes |
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newbie333 Guest
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Posted: Tue Sep 09, 2008 10:11 am |
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INPUT is = 1
and
OUTPUT = 0
Therefore I think the state should be
TRISB = TRISB & (~(0x1 &1))
however it seems that i have been been an idiot, in CCS INPUT is a reserved word therefore it is getting confused.. need to change
INPUT to something else ie
#define DIR_INPUT 1
#define BUTTON1_D DIR_INPUT
and then
BUTTON1_SET_TRIS (TRISB&= ~(BUTTON1_B & BUTTON1_D))
it seems to work now.
thanks |
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