Post by thread:[PIC]:Problem with TMR0 and ICD stepping

Searched the archives and saw somebody had a similar problem but was not helped. When I step through my progam with ICD , TMR0 shows all kinds of values and seems to have no sequence in it. I use internal clock and 1:256 prescaler, 20Mhz on a 16F876. At first I thought it was because of the debugging program that runs during and after each step adding a few counts on (still a posibility), but with a prescaler that high, surely I must see a sequence. I also preload TMR0 with a value at overflow (using interupt). Everytime I load the value, TMR0 shows a different value everytime. Removing the prescaler has no affect on stepping, how ever I see a difference on my project when I run it. I run the same program through the simulator, and TMR0 works fine. Is this a know problem? Guess I have to do my debugging with this the hard way. Quentin -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> When I step through my progam with ICD , TMR0 shows all kinds of values > and seems to have no sequence in it. > I use internal clock and 1:256 prescaler, 20Mhz on a 16F876. > At first I thought it was because of the debugging program that runs > during and after each step adding a few counts on (still a posibility), > but with a prescaler that high, surely I must see a sequence. > I also preload TMR0 with a value at overflow (using interupt). Everytime > I load the value, TMR0 shows a different value everytime. > Removing the prescaler has no affect on stepping, how ever I see a > difference on my project when I run it. > I run the same program through the simulator, and TMR0 works fine. I don't use the ICD, so I'm only guessing. Since you are single stepping, the PIC is presumably spending most of its time waiting for the next command. That would certainly be a "long" time with many timer 0 wrap arounds occurring. It would make sense that the timer 0 value is essentially randomized by the ICD between steps. Again, I'm guessing, but this may be a limitation of the ICD. You can get a lot of debugging done using the simulator with a little cleverness. The other alternative is the ICE which doesn't mess up timer 0. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, spam_OUTolinTakeThisOuTembedinc.com, http://www.embedinc.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

Hi Quentin, > When I step through my progam with ICD , TMR0 shows all kinds > of values > and seems to have no sequence in it. i havn't used the ICD yet, but AFAIK the ICD has special code in the last 100 hex words of ROM, which is executed after matching the breakpoint address. Since this ICD code is normal code, TMR0 is updated continuesly. You have to use a full emulator (ICE2000, ICEPIC,...) to measure TMR0 in real time. The ICD is not the right debugging tool for your problem. Best regards, Frank GSP Sprachtechnologie GmbH Frank Wollenberg HW-Entwicklung Tel.: +49 (0)30 769929-78 Fax: +49 (0)30 769929-12 eMail: .....f.wollenbergKILLspam@spam@gsp-berlin.de -- GSP Sprachtechnologie GmbH Teltowkanalstr.1, D-12247 Berlin Tel.: +49 (0)30 769929-0 Fax: +49 (0)30 769929-12 eMail: InfoKILLspamgsp-berlin.de Web: http://www.gsp-berlin.de -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body