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Eoin87
Joined: 20 Oct 2009
Posts: 18
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| PIC24F address error |
 Posted: Tue May 29, 2012 6:58 am |
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Hi all,
I'm using PIC24F16KA102 and CCS 4.124. I have some complex code working fine but there is one address error that is driving me crazy.
I included the following code to debug the error.
| Code: |
#int_ADDRERR
void ae_isr (void)
{
#asm
mov w15, w0
sub #36, w0
mov [w0++], w1
mov w1, trapaddr
mov [w0], w1
and #0x7f, w1
mov w1, trapaddr+2
#endasm
set_radio_mode (rf_sleep, 0) ;
rtcie=false;
//sleep (sleep_full) ;
while (1);
}
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If I look at the variable Trapaddr I see a value of 0XAB2, if I check this line of code in the assembly listing I see the following code.
| Code: |
552: if (*r_rssi>15)
0AB2 805580 mov.w 0x0ab0,0x0000
0AB4 784210 mov.b [0x0000],0x0008
0AB6 E1246F cp.b 0x0008,#15
0AB8 360003 bra leu, 0x000ac0
1553: *r_rssi=15;
0ABA 805585 mov.w 0x0ab0,0x000a
0ABC B3C0F0 mov.b #0xf,0x0000
0ABE 784A80 mov.b 0x0000,[0x000a]
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*r_rssi is passed into this function as an unsigned char *r_rssi and the address of declared byte is passed into this function.
Does anyone have any ideas why this code might be causing an Address error? I am quite sure this code is already being called multiple times but I can see the chain of events and one particular place where its called from which causes the error.
Eoin |
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Tressie
Joined: 07 Apr 2012
Posts: 12
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| Address Error |
| Posted: Fri Jul 06, 2012 6:02 am |
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Hi Eoin87,
Did you ever manage to find the cause of your address error reset, because I have exactly the same thing happening.
Regards,
T.  |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Fri Jul 06, 2012 10:56 am |
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| There's no address error at 0xAB2, the faulty instruction is one assembly line above, not shown in the post. |
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Tressie
Joined: 07 Apr 2012
Posts: 12
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| Posted: Fri Jul 06, 2012 2:38 pm |
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| FvM wrote: | | There's no address error at 0xAB2, the faulty instruction is one assembly line above, not shown in the post. |
Hi FvM. Nice to have your expertise along for the ride.
Well, if the PCD V4.081 address error trap handler/ debug code is good for PCD V4.132 as well, then the source of my address error reset seems to be within some code that the compiler automatically adds just after a device header include statement. PCD bug, maybe?
The use of certain other sections of code (ModBus CRC calculation), or the use of CCS EEPROM access code elsewhere in the project seems to be triggering the exception condition, but nothing short of omitting the offending statements and subroutine calls will help. I can't seem to find any of the known address error causes in the spacially unrelated trap inducing source, so I'm stumped.
Okay, I'm now handling the exception that the second address error invokes, so the controller no-longer resets. As far as I can tell, the error and subsequent trap have no effect on my program's operation, and everything continues on swimmingly just after the error handler completes. What might be the implications of just leaving it there?
Regards,
T. 
We |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Fri Jul 06, 2012 4:13 pm |
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There have been PCD bugs that raise an address error, but in most cases they are brought up by user code errors. The final error can also occur in library code, e.g. if a function is supplied with wrong parameters. In so far I won't guess about the cause for your observations.
With some basic understanding of PIC24 instruction set, you should be able to "see" the cause for an address error when analyzing the code. In special cases, it may be necessary to trace code execution at the disassembly level in MPLAB debugger. Sometimes the problem can be reproduced in MPLAB SIM, without actual processor hardware.
If an address error is handled by exception routine, the instruction causing the error is skipped. If this instruction isn't superfluous (most likely it isn't), a required calculation result will be missing. |
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