Post by thread:[PIC]:weird jump of program to other program memor

There are a dozen possible causes. It is useful to list some of the ones that have caught me: 1. Defining two variables to the same memory location, then wondering why one of them changes seemingly randomly 2. Partial Resets due to noise on the MCLR line not completely resetting the PIC and leaving it in an unknown state 3. EMI noise from an adjacent relay changes PIC registers 4. Unexpected WDT reset due to not putting WDT reset statements in proper places 5. Timer interrupts not behaving as I thought they would due to thumb-fingered programming of TIMERH and TIMERL registers 6. In assembler, messy stack issues when an interrupt trashes a key register like w (C compilers are supposed to deal with this auto-magically) 7. Leaving undefined states in any area of the program. For example: char i; i= 10; do{ some stuff }while(i--); is perfectly acceptable in C Programming 101 but does not define behaviour if noise or programming pencilheadedness enters the loop with I = 254. char i; i= 9; do{ some stuff }while(--i < 9 ); will define behavior for every possible value of i. 8. Ground bounce due to motors, inductive loads, or other heavy loads on same ground bus as PIC, inadequate grounding and PCB layout 9. Fried PIC pins. The plucky PIC will still run after a bus fight has destroyed two or three I/O pins, as long as they aren't shorted. And the top 10 reason for this behaviour is: 10. Dumb programming mistakes. Pick apart your program pretending that your worst enemy wrote it and you have to prove he is an idiot to win a million bucks. You will find the problem very quickly. I have done all of these and spent a half a day each on them until I went "D'OH" and figured them out. Tell us a little more detail and we can help you more specifically. -- Lawrence Lile paul sayuj <spam_OUTpaul_sayujTakeThisOuTYAHOO.CO.IN> Sent by: pic microcontroller discussion list <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> 10/25/2003 02:10 AM Please respond to pic microcontroller discussion list To: PICLISTKILLspamMITVMA.MIT.EDU cc: Subject: PIC:weird jump of program to other program memory location hi, I am facing a frustrating problem. My program is jumping to other program location not according to the flow of program.what may be the cause of it? paul sayuj ________________________________________________________________________ Yahoo! India Matrimony: Find your partner online. Go to http://yahoo.shaadi.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

A prime example of what I termed "pencilheaded programming errors" in my previous post. My favorite compiler defaults to unsigned char, but others probably do something different. Some others might assume the number 10 means 0x10 AFAIK. -- Lawrence Lile @spam@piclistKILLspamXARGS.COM Sent by: pic microcontroller discussion list <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> 10/27/2003 01:56 PM Please respond to pic microcontroller discussion list To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU cc: Subject: Re: [PIC]:weird jump of program to other program memory location On Mon, 27 Oct 2003 spamBeGonellilespamBeGoneSALTONUSA.COM wrote: > char i; > i= 9; > do{ > some stuff > }while(--i < 9 ); > > will define behavior for every possible value of i. I think you meant "unsigned char i"? The code above runs the loop 138 times when "char" is signed. -- John W. Temples, III -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email TakeThisOuTlistservEraseMEspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

On Mon, 27 Oct 2003 EraseMEllileSALTONUSA.COM wrote: > My favorite compiler defaults to unsigned char, but others > probably do something different. Whether a "char" is signed or unsigned is implementation-dependent. A "char" is meant to store an ASCII character, not to be used as a general-purpose integer. For this purpose, you'd wanted to specify a "signed char" or an "unsigned char." > Some others might assume the number 10 means 0x10 AFAIK. Perhaps an assembler would, but not a C compiler. > On Mon, 27 Oct 2003 RemoveMEllileEraseMEEraseMESALTONUSA.COM wrote: > > > char i; > > i= 9; > > do{ > > some stuff > > }while(--i < 9 ); > > > > will define behavior for every possible value of i. -- John W. Temples, III -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservspam_OUTKILLspammitvma.mit.edu with SET PICList DIGEST in the body