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jameszum
Joined: 31 Jan 2012
Posts: 14
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| using #define on multiple pins |
 Posted: Tue Sep 27, 2016 1:30 pm |
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Good Morning
I am working on a project where I have a number of control lines going off to a number of modules. It would be nice if I were able to put the control lines in n array such as
| Code: | | #define port_select[8] {PIN_F13,PIN_B14,PIN_H6,PIN_F2,PIN_A14,PIN_A4,PIN_H14,PIN_D13}; |
is this possible?
coding would be something like
| Code: | | for i=0; i<9; i++) output_high(port_select[i]) ; |
Thank you |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 27, 2016 2:32 pm |
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I don't have the PCD compiler, but I made a test program for an 18F PIC.
| Code: |
#include <18F8722.h>
#fuses INTRC_IO,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4M)
int16 port_select[8] = {PIN_F3,PIN_B4,PIN_H6,PIN_F2,PIN_A5,PIN_A4,PIN_H4,PIN_D3};
//======================================
void main(void)
{
int8 i;
for(i=0; i<8; i++)
{
output_high(port_select[i]);
}
while(TRUE);
} |
Now look at the for() loop in the .LST file:
| Code: |
.................... for(i=0; i<8; i++)
0009A: CLRF 14
0009C: MOVF 14,W
0009E: SUBLW 07
000A0: BNC 00E2
.................... {
.................... output_high(port_select[i]);
000A2: BCF FD8.0
000A4: RLCF 14,W
000A6: CLRF 03
000A8: ADDLW 04
000AA: MOVWF FE9
000AC: MOVLW 00
000AE: ADDWFC 03,W
000B0: MOVWF FEA
000B2: MOVFF FEC,16
000B6: MOVF FED,F
000B8: MOVFF FEF,15
000BC: MOVFF 15,17
000C0: MOVLW 01
000C2: MOVWF 18
000C4: MOVLW 0F
000C6: MOVWF 1A
000C8: MOVLW 89
000CA: MOVWF 19
000CC: RCALL 0004
000CE: MOVFF 15,17
000D2: CLRF 18
000D4: MOVLW 0F
000D6: MOVWF 1A
000D8: MOVLW 92
000DA: MOVWF 19
000DC: RCALL 0004
000DE: INCF 14,F
000E0: BRA 009C |
That's not all of it. Here's the routine at address 0x00004 that it calls:
| Code: | 00004: MOVF 17,W
00006: ANDLW 07
00008: MOVWF 00
0000A: RRCF 17,W
0000C: MOVWF 01
0000E: RRCF 01,F
00010: RRCF 01,F
00012: MOVLW 1F
00014: ANDWF 01,F
00016: MOVF 01,W
00018: ADDWF 19,W
0001A: MOVWF FE9
0001C: MOVLW 00
0001E: ADDWFC 1A,W
00020: MOVWF FEA
00022: CLRF 01
00024: INCF 01,F
00026: INCF 00,F
00028: BRA 002C
0002A: RLCF 01,F
0002C: DECFSZ 00,F
0002E: BRA 002A
00030: MOVF 18,F
00032: BZ 003A
00034: MOVF 01,W
00036: IORWF FEF,F
00038: BRA 0040
0003A: COMF 01,F
0003C: MOVF 01,W
0003E: ANDWF FEF,F
00040: RETURN 0 |
So indirect addressing of i/o pins is incredibly inefficient and time-consuming. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19552
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| Posted: Tue Sep 27, 2016 2:35 pm |
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No.
Just use a constant array.
| Code: |
const unsigned int16 port_select[8]
= {PIN_F13,PIN_B14,PIN_H6,PIN_F2,PIN_A14,PIN_A4,PIN_H14,PIN_D13};
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#defines are not code or variables. They are 'text substitution macros' all done at compile time/ you can substitute in 'values', but not pick parts of them like this.
However the pin 'names', themselves are just #defines, and are really just numbers.
Also 'beware'. A 'output_high' using a variable, is a lot larger/slower than the output_high on a constant value. You'll probably find it is smaller and quicker to just have the 8 values hard coded.....
After posting, I see PCM_Programmer also pointed this out, while I was typing.  |
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jameszum
Joined: 31 Jan 2012
Posts: 14
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| Posted: Tue Sep 27, 2016 2:40 pm |
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| Thank you |
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jameszum
Joined: 31 Jan 2012
Posts: 14
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| Posted: Tue Sep 27, 2016 2:43 pm |
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| Thank You |
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