Post by thread:[PIC]: Calibration information of PIC

Hi, I read that for PIC with an internal OSC, there are likely to have a calibration information store in the last location of program memory. When I do a erase operation with MPLAB + ICD2, will those combination of tools restore the calibration information after erasing the device? Thanks & regards. WH Tan -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

WH Tan wrote : > I read that for PIC with an internal OSC, there are likely to have a > calibration information store in the last location of program memory. Yes, for "older" PICs with the old style INTOSC. No, for "newer" PICs with the new style INTOSC. Why don't you just check the data sheet for your PIC ? To easy maybe ? :-) :-) > When I do a erase operation with MPLAB + ICD2, will those > combination of tools restore the calibration information after > erasing the device? Any "real" programmer should take care of this, if needed, see above. I'd be very surprised if Microchips own tools doesn not... It would have helped a *lot* to know what PIC you are using. Regards Jan-Erik. -- 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 Jan-Erik, Thank you very much for your response. I am using PIC12F675. Yes, I had read the datasheet already. That make me think that that always a calibration data stored in last location. My main concern is that will the data being read & restored during erase operation. I had been serching Microchip's web site but couldn't find an answer. Regards, WH Tan PS: Thanks a lot to your recent post to my subject "Multi-tasking with PIC". I found a solution now. -- 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

WH Tan wrote : > I am using PIC12F675. OK, Well that is definitly a "newer" PIC, but it doesn't use the new INTOSC with builtin factory calibration without the RETLW instruction in the last Flash position. So any programmer doing a bulk erase must preserv that, as you say... > Yes, I had read the datasheet already. > That make me > think that that always a calibration data stored in last location. On *that* PIC (and some others), yes. If you have a few minutes to spare, you could always study the OSC part in, let's say, the 18F1220 data sheet. > My main concern is that will the data being read & restored > during erase > operation. I had been serching Microchip's web site but > couldn't find an answer. Can not help here. I'm using Wouters Wisp628 which (as far as I know and have seen) handles this on the 12F parts. > PS: Thanks a lot to your recent post to my subject > "Multi-tasking with PIC". I found a solution now. Fine ! Now, part of the joy of helping is to get to know how the problem finaly was solved. So, what was the solution ? Regards, Jan-Erik. -- 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

>Now, part of the joy of helping is to get to know how the >problem finaly was solved. So, what was the solution ? Hi Jan-Erik, Would you mind if I send the complete code to you? I am worry the asm file will cause my mail being rejected by the list server. WH Tan -- 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

WH Tan wrote : > Would you mind if I send the complete code to you? I am worry > the asm file will cause my mail being rejected by the list server. No, I was just thinking of a few words *describing* what you did :-) :-) After all, that was how this was discussed from the beginning, I don't remember ever seeing any code, right ? And, actualy, there *might* be others that was part of the thread that might be interested, what do I know... Best Regards Jan-Erik. -- 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

Ok. No problem. Here is the solution. My main goal was to distinguish Start/Stop (300us/700us respectively) or 1/0 bits (70us/10us respectively). I set up a loop which will continually read the input pin and store in C. Later on this will be shift into 4 register. SHIFT rlcf OUTBUFFER, f ; rlcf OUTBUFFER+1, f ; rlcf OUTBUFFER+2, f ; rlcf OUTBUFFER+3, f ; This introduce some delay to waveform so that the PIC will always have some time to process the incoming waveform to strip out the start/stop bits. When it is a 'high' a counter will start decremented. The initial value was choose so that a pulse that is shorter that 100us will never reach zero. If this counter reach zero, then the incoming pulse was either a start or stop bit. If this is the case, another counter will start decremented (800us). This is the counter used to strip the start/stop bit. During this period, the MSB of the shift register will always been cleared before a shift operation was performed. Any comment to this? Thanks & regards, WH Tan -- 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