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ellrod
Joined: 14 Dec 2004 Posts: 6 Location: Boston, Ma
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set_tris_a problem |
Posted: Tue Dec 14, 2004 3:47 pm |
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Here's one I've been beating on for a couple of hours now....
#include <16F88.H>
#fuses INTRC_IO,NOWDT,NOPROTECT,NOBROWNOUT,NOMCLR,NOFCMEN,NOIESO,NOLVP,CCPB3
#use fast_io(a)
#use fast_io(b)
#byte trisa_x = 0x85
#byte trisb_x = 0x86
The following sets trisa properly, to 0xE2
void main() {
trisa_x = 0xe2;
trisb_x = 0xd1;
// body of code here
}
This next code does not work correctly, it sets trisa to 0x22
void main() {
set_tris_b(0xd1);
set_tris_a(0xe2);
// body of code here
}
In looking at the assembly language I see this:
262: set_tris_b(0xd1);
000625 30D1 MOVLW 0xd1
263:
264: set_tris_a(0xe2);
000627 30E2 MOVLW 0xe2
265
The actual instuctions that write the tris registers is hidden (locs 263 and 265) so I don't know what CCS is doing there.
Anybody know what's going on here ?
Thanks ! _________________ Arnie Jones
Contract Embedded Systems Developer |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Dec 14, 2004 3:50 pm |
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Those are not address locations. Those are line numbers in the .LST file.
Also, be aware that TRISA only uses the lower 6 bits of the register.
The upper two bits are not used, and are likely read back as zeros.
Hence, 0xE2 becomes 0x22. |
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ellrod
Joined: 14 Dec 2004 Posts: 6 Location: Boston, Ma
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Posted: Tue Dec 14, 2004 4:45 pm |
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Sorry, I meant to say lines 626 and 628, which are code locs, are not included anywhere in the disassembly listing.
Both A and B ports on the 16F88 are full eight bits wide so the upper tris bits are utilized. _________________ Arnie Jones
Contract Embedded Systems Developer |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Dec 14, 2004 4:52 pm |
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You are right. I clicked on 16F688 by mistake in my list of data sheets.
(Trying to answer too quickly...)
What version of the compiler are you using, and what IDE are you using ?
(MPLAB or CCS PCW) |
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ellrod
Joined: 14 Dec 2004 Posts: 6 Location: Boston, Ma
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Posted: Tue Dec 14, 2004 5:12 pm |
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MPLAB 6.62 and CCS 3.209 _________________ Arnie Jones
Contract Embedded Systems Developer |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Dec 14, 2004 5:20 pm |
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Here is something disturbing. If I install PCM vs. 3.209 and compile the
test file shown below, I get illegal TRIS instructions shown in the .LST file.
Code: |
#include <16F88.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)
void main()
{
set_tris_b(0xd1);
set_tris_a(0xe2);
while(1);
} |
Code: | // Part of the .LST file follows:
CCS PCM C Compiler, Version 3.209, xxxxx 14-Dec-04 15:16
0000 00298 ....................
0000 00299 .................... set_tris_b(0xd1);
0011 30D1 00300 MOVLW D1
0012 0066 00301 TRIS 6
0000 00302 .................... set_tris_a(0xe2);
0013 30E2 00303 MOVLW E2
0014 0065 00304 TRIS 5
0000 00305 ....................
0000 00306 .................... while(1);
0015 2815 00307 GOTO 015 |
Can you go into your Project/ Build Options menu and select "MPASM
Format" for the List File format ? Then re-compile and see if you get
the output as shown above ? |
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drh
Joined: 12 Jul 2004 Posts: 192 Location: Hemet, California USA
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Posted: Tue Dec 14, 2004 5:29 pm |
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There is some information about CCS using the TRIS instructions in the Q&A section of the manual. There really don't explain why they use it though. _________________ David |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Dec 14, 2004 5:39 pm |
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Yes, but the TRIS instruction is not even in the 16F88 data sheet.
They shouldn't be using it. I compiled the program above with
several other versions of the compiler (3.168, 3.188, 3.214) and
it has the same problem. That's why I wanted to see if he also
sees the TRIS instruction in his .LST file. I want some confirmation
that I'm really seeing a bug here. |
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ellrod
Joined: 14 Dec 2004 Posts: 6 Location: Boston, Ma
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Posted: Tue Dec 14, 2004 6:44 pm |
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That's the odd thing, as you can see in the original fragment of the .lst file I posted the instuction immediately following the MOVLW <tris value> is not included in the listing, it's just skipped over. I know there's something there since the address is incremented. I will look at some way of disassembling the object file to see what is put there. _________________ Arnie Jones
Contract Embedded Systems Developer |
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Mark
Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA
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Posted: Tue Dec 14, 2004 6:52 pm |
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Quote: | I will look at some way of disassembling the object file to see what is put there.
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View\Program Memory |
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Guest
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Posted: Tue Dec 14, 2004 8:27 pm |
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Out of the office till tomorrow, will check it out first thing in the morning.... |
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adrian
Joined: 08 Sep 2003 Posts: 92 Location: Glasgow, UK
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Posted: Wed Dec 15, 2004 7:01 am |
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Quote: |
Here is something disturbing. If I install PCM vs. 3.209 and compile the
test file shown below, I get illegal TRIS instructions shown in the .LST file.
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From the CCS online help
Quote: |
The use of TRIS causes concern for some users. The Microchip data sheets recommend not using TRIS instructions for upward compatibility. If you had existing ASM code and it used TRIS then it would be more difficult to port to a new Microchip part without TRIS. C does not have this problem, however; the compiler has a device database that indicates specific characteristics for every part. This includes information on whether the part has a TRIS and a list of known problems with the part. The latter question is answered by looking at the device errata.
CCS makes every attempt to add new devices and device revisions as the data and errata sheets become available.
PCW users can edit the device database. If the use of TRIS is a concern, simply change the database entry for your part and the compiler will not use it.
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ellrod
Joined: 14 Dec 2004 Posts: 6 Location: Boston, Ma
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Posted: Wed Dec 15, 2004 7:50 am |
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Here is the C code:
#include <16F88.H>
#fuses INTRC_IO,NOWDT,NOPROTECT,NOBROWNOUT,NOMCLR,NOFCMEN,NOIESO,NOLVP,CCPB3
#use fast_io(a)
#use fast_io(b)
#byte trisa_x = 0x85
#byte trisb_x = 0x86
void main()
{
trisa_x = 0xd1;
trisb_x = 0xe2;
set_tris_b(0xd1);
set_tris_a(0xe2);
}
Here is the assembly that is generated
1 0000 3000 MOVLW 0
2 0001 008A MOVWF 0xa
3 0002 2804 GOTO 0x4
4 0003 0000 NOP
5 0004 0184 CLRF 0x4
6 0005 301F MOVLW 0x1f
7 0006 0583 ANDWF 0x3, F
8 0007 1683 BSF 0x3, 0x5
9 0008 121F BCF 0x1f, 0x4
10 0009 129F BCF 0x1f, 0x5
11 000A 081B MOVF 0x1b, W
12 000B 3980 ANDLW 0x80
13 000C 380F IORLW 0xf
14 000D 009B MOVWF 0x1b
15 000E 3007 MOVLW 0x7
16 000F 1283 BCF 0x3, 0x5
17 0010 009F MOVWF 0x1f
18 0011 30D1 MOVLW 0xd1
19 0012 1683 BSF 0x3, 0x5
20 0013 0085 MOVWF 0x5
21 0014 30E2 MOVLW 0xe2
22 0015 0086 MOVWF 0x6
23 0016 30D1 MOVLW 0xd1
24 0017 0066
25 0018 30E2 MOVLW 0xe2
26 0019 0065
27 001A 0063 SLEEP
Instructions 66 and 65 are TRISA and TRISB instructions !
Single stepping through this code I find that when the TRISA instruction is executed instead of E2 being loaded into TRISA 22 is loaded. Using a movf instruction to load TRISA it gets loaded properly.
Another thing that pops out at me when looking at this code is that it messes around with location 0x1b ! Which is a reserved location in the 16F88, if I try to assemble this code with MPASM it warns of an illegal address at 0x1b. _________________ Arnie Jones
Contract Embedded Systems Developer |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Wed Dec 15, 2004 10:01 am |
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Regarding the quote from the CCS manual, the issue is that
CCS doesn't use TRIS for 16F877. See the code below, compiled
with PCM 3.214. They fixed it years ago for the 16F877. Therefore
I think it's a bug for the 16F88, and should be reported to CCS.
That quote in the manual has been in there for years and doesn't
really apply anymore, in my opinion.
Code: | 0000 00293 ......... void main()
0000 00294 ......... {
0004 0184 00295 CLRF 04
0005 301F 00296 MOVLW 1F
0006 0583 00297 ANDWF 03,F
0007 1683 00298 BSF 03.5 // Select Bank 1
0008 141F 00299 BSF 1F.0
0009 149F 00300 BSF 1F.1
000A 151F 00301 BSF 1F.2
000B 119F 00302 BCF 1F.3
0000 00303 .........
// Notice how the TRIS registers are loaded with MOVWF
// instructions for the 16F877, and not the obsolete TRIS:
0000 00304 ......... set_tris_b(0xd1);
000C 30D1 00305 MOVLW D1
000D 0086 00306 MOVWF 06
0000 00307 ......... set_tris_a(0xe2);
000E 30E2 00308 MOVLW E2
000F 0085 00309 MOVWF 05
0000 00310 .........
0000 00311 ......... while(1);
0010 2810 00312 GOTO 010
0000 00313 .................... } |
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Guest
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Posted: Wed Dec 15, 2004 11:57 am |
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I checked the 16F88 in the Device Selector under Tools (I am using PCW) and the under the heading for "other features" the first item is TRIS. This is set to TRUE. I checked the f877 and the TRIS feature is set to FALSE. I am almost certain that whoever created the device in the selector just copied the format from some other part.
I compiled the original program with the default device selector entries and the TRIS instruction was used. I then used the device selector and changed the TRIS feature to FALSE, and sure enough, the result was as follows: (the following is hand typed since my compiler is on another machine)
Code: |
.................... set_tris_b(0xd1);
0011: MOVLW D1
0012: BSF 03.5
0013: MOVWF 06
.................... set_tris_a(0x02)
0014: MOVLW 02
0015: MOVWF 05
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I am not certain how to edit the device if you are using the command line version. PCM Programmer, can you help with that? |
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