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Hicham
Joined: 09 Feb 2010
Posts: 17
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| set_tris_x( ) & PIC16F84 |
 Posted: Mon Feb 15, 2010 2:16 pm |
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Hello,
I used set_tris_x( ) function to configure PIC16F84 ports, like this :
and I got an error in Proteus
I checked the LST file..and found out that the asm code generated by the compiler for this function is
| Code: |
.................... set_tris_a(0x00);
0007: MOVLW 00
0008: TRIS 5
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is this a bug or my misunderstood of the of PIC C compiler ? coz TRIS doesn't exist. So how can I fix it, I heard that I can modify existing function in PIC-C, How ?
Since I'm a fan of assembly language, I did this small modification.
| Code: |
#asm
bsf STATUS,5 // bit6 EQU RP0, go to BANK1
bcf TRISA,0
bcf TRISA,1
bcf TRISA,2
//or
movlw 0x00
movwf TRISA // all PORTA pins are in output mode
#endasm
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And it works 
Also, I notice that the function output_high/low(PIN_X)
always configure the bit first as an output, and then set the bit high or low.
| Code: |
.................... output_high(PIN_A2);
0025: BSF 03.5
0026: BCF 05.2
0027: BCF 03.5
0028: BSF 05.2
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I read that this is an instant output configuration or something like that.
My question is, Why always configuring the bit, while, in most cases, you use a pin as an input or an output and not both, in the same program.
Any help from expert people here. It will be much appreciated.
--------------------
sorry for my english |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Feb 15, 2010 2:25 pm |
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| Quote: |
coz TRIS doesn't exist
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The TRIS instruction sure does exist for the 16F84. Download the 16F84
data sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/30430c.pdf
Go to page 69. There is a gray box for the TRIS instruction.
It says:
| Quote: |
TRIS -- Load TRIS Register
Description:
The instruction is supported for code
compatibility with the PIC16C5X products.
Since TRIS registers are readable
and writable, the user can directly
address them.
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| Quote: | | always configure the bit first as an output, and than set the bit high or low |
That's "standard i/o mode" in CCS. It's the default mode of the compiler.
You can also specify "fast i/o mode" for an i/o Port, and the compiler will
not automatically set the tris in that case. You then have to set the tris
with a set_tris_x() statement. See the CCS manual.
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf
| Quote: | | My question is, Why... |
CCS is designed (at the default level) to make everything as easy as
possible. Unlike Hi-tech C (for example) where you have to specify
much more, just to make a program work. CCS is for "rapid development".
You can whip out a program very quickly. But, if you want to, you can
use other CCS features do more low level programming (which you
seem to want to do). |
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Hicham
Joined: 09 Feb 2010
Posts: 17
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| Posted: Tue Feb 16, 2010 2:11 am |
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#PCM programmer
thanks for the help
but the instruction TRIS is valid just for PIC16C5X and not for pic16F84. right ?
and i choose pic16F84A to program ????
any idea ? |
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bungee-
Joined: 27 Jun 2007
Posts: 206
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| Posted: Tue Feb 16, 2010 6:25 am |
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TRIS work's on every PIC that I know of.
If you program in CCS you do not need to use that function (TRIS) because CCS will do that for you. I was programming the PIC16F84A with CCS and I was using the TRIS function because of some time important function on low speed clock and everything was working like a charm. And when you want to use that kind of port direction programming you have to tell that to the compiler with #use fast_io(A)
I reckon that it is problem in Proteus not in CCS....
Try to use the real hardware  |
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Hicham
Joined: 09 Feb 2010
Posts: 17
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| Posted: Tue Feb 16, 2010 1:27 pm |
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#bungee-
like i said, Proteus show me an error about this function. that's why i asked
but i'll test it in real circuit to be sure about it
thanks for your help. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Feb 16, 2010 1:39 pm |
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| Quote: | | but the instruction TRIS is valid just for PIC16C5X and not for pic16F84. right ? |
How did you decide that ? I repeat, the 16F84 data sheet says clearly:
| Quote: |
TRIS -- Load TRIS Register
Description:
The instruction is supported for code
compatibility with the PIC16C5X products.
Since TRIS registers are readable
and writable, the user can directly
address them.
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| Quote: |
and i choose pic16F84A to program ????
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You were using the 16F84. Now you suddenly change to 16F84A.
But, the 16F84A data sheet also says TRIS is supported for that PIC.
http://ww1.microchip.com/downloads/en/DeviceDoc/35007b.pdf
On page 80 of the data sheet, it says this:
| Quote: |
4. Four new instructions have been added:
RETURN, RETFIE, ADDLW, and SUBLW. Two
instructions, TRIS and OPTION, are being
phased out, although they are kept for
compatibility with PIC16C5X.
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Therefore the TRIS instruction is supported, and is legal to use, for
both the 16F84 and 16F84A.
This is really a Proteus problem. It's not the fault of CCS in this case.
However, if you have the IDE version of the compiler (PCW, PCHW, etc),
I believe you may be able to use the Device Editor to modify the Device
Data for those PICs so they doesn't use the TRIS instruction.
I don't have the IDE version of the compiler. But here's a screenshot
of the Device Editor. You can probably disable use of the TRIS instruction
by "unchecking" TRIS instruction tickbox in the Features section, or
possibly it may be in another section:
http://www.ccsinfo.com/images/content/device_editor.gif
For more information, see this CCS FAQ article on the TRIS instruction:
http://www.ccsinfo.com/faq.php?page=ccs_tris |
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Hicham
Joined: 09 Feb 2010
Posts: 17
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| Posted: Wed Feb 17, 2010 4:20 am |
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| Quote: | Quote:
but the instruction TRIS is valid just for PIC16C5X and not for pic16F84. right ?
How did you decide that ? I repeat, the 16F84 data sheet says clearly: |
Well, I guess I didn't read it well, sorry about the pic I'm using, its 16F84A.
And thanks for the information about the IDE. I'll try this option. |
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