Post by thread:[EE]:Observations and questions

Hi and to all a happy new year, New to pics! 1. I have a 16F84 config in HS with 3.2768 Mhz Xtal and 2x20pf caps to GND. I was expecting a reasonably accurate time base but after an 8 hour test was about 8 secs slow. I have seen in other MSG's reference to 32 khz watch xtals used but thought that the error would have to be less using a Mhz xtal Should I get better accuracy than this and if not how is a more accurate timebase derived. I get my *second* from the following fsec = 3 276 800 / (execution rate * prescaler * max count tmr0 * FILE counter) =3 276 800 / (4 * 128 * 256 * 25) =1 2. Used CMOS chips(4094) for the first time (always used TTL cause I like em) on this project and powered up before checking connections (as I tend to do) all worked well. Then discovered that the GND pin was not connected. Was impressed to see this chip function as it was sinking current for a seven seg disp. Just an observation 3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) stand for. 4. Windose (hee hee) ME does not appear to have the 'attrib' command and cant believe they took away DOS MODE. (Still has a DOS Box thou ) 5. What does it mean to have an embedded processor?. Is the processor in my washing machine embedded? Is the HC11 an embedded processor? Is the one in my PC embedded? Regards Justin ps Thanks for some really interesting reading even managed to answer some but by the time I get to reconnect I find the topic completely thrashed out. I must confess since subscribing I have spent very little time actually doing the project and wonder just how some of you find the time to do both. Thanks again . -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

>1. I have a 16F84 config in HS with 3.2768 Mhz Xtal and 2x20pf caps to GND. I was expecting a reasonably accurate time base but after an 8 hour test was about 8 secs slow. I have seen in other MSG's reference to 32 khz watch xtals used but thought that the error would have to be less using a Mhz xtal Didn't look at your code, but there could be two hardware reasons. HS mode at 3 MHz is driving your crystal pretty hard. Or maybe you are using a series crystal, you should use a parallel crystal. Cheers, Bob -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

On Mon, 1 Jan 2001 13:27:58 +1100, you wrote: >Hi and to all a happy new year, > >New to pics! > >1. I have a 16F84 config in HS with 3.2768 Mhz Xtal and 2x20pf caps to GND. I was expecting a reasonably accurate time base but after an 8 hour test was about 8 secs slow. I have seen in other MSG's reference to 32 khz watch xtals used but thought that the error would have to be less using a Mhz xtal > >Should I get better accuracy than this and if not how is a more accurate timebase derived. You can normally expect 50-100ppm from a normal crystal (excluding temp changes) so something is wrong - using HS mode is probably not a good idea as it will be overdriving the xtal. >2. Used CMOS chips(4094) for the first time (always used TTL cause I like em) on this project and powered up before checking connections (as I tend to do) all worked well. Then discovered that the GND pin was not connected. Was impressed to see this chip function as it was sinking current for a seven seg disp. Just an observation CMOS chips (ebven PICs) will often 'find' power and GND via their input protection diodes if unconnected. Needless to say you are also likely to see some strange things happening.... >3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) stand for. Talk To You Later, In My Humble Opinion, For All I Know, As Far As I Know >5. What does it mean to have an embedded processor?. Is the processor in my washing machine embedded? Is the HC11 an embedded processor? Is the one in my PC embedded? Generally, a processor is described as 'embedded' when the presence of a processor is not directly obious to the user, and/or 'data processing' is not the principal purpose of the product. Any processor _can_ be (and probably has been) embedded, but small microcontrollers like the PIC are by far the most common, being specifically designed for this type of application. Obviously there is some scope for semantic arguments, but the main processor in your PC would not normally be described as being an embedded processor, but the ones in your keyboard, mouse, printer, modem etc. would. -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

>> 1. I have a 16F84 config in HS with 3.2768 Mhz Xtal and 2x20pf caps to GND. I was expecting a reasonably accurate time base but after an 8 hour test was about 8 secs slow. << That's .03% accuracy. What's the crystal rated at? Also, are you sure you need HS mode? I don't have the 16F84 data sheet in front of me, but usually you don't need HS mode until 4 or 8 MHz. >> 3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) stand for. << It stands for "I'm too lazy to type a few extra letters and too arrogant to care that not everyone can remember all the silly abbreviations". I usually just skip over this crap when reading, especially if the poster wants something from me rather than the other way around. I sorta recall IMHO = In My Humble Opinion, AFAIK = As Far As I Know, and I don't remember TTYL. > 5. What does it mean to have an embedded processor?. An embedded processor is one that is built into something for performing a particular dedicated task. The end user doesn't have access to the processor to run arbitrary programs. > Is the processor in my washing machine embedded? Yes. > Is the HC11 an embedded processor? Embedded is defined by use, not by processor type. However, those processors like the HC11 and PICs that are designed for embedded microcontroller use usually don't have the facilities to make them viable non-embedded computers. Some of the processors that are designed for general purpose non-embedded computing can also be used in an embedded way. One project I worked on used a Pentium as an embedded processor. This same machine could have run Windows, but instead was running a real time control program. Various flavors of the Power PC are often used in embedded systems that need significant horsepower. > Is the one in my PC embedded? No. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, .....olinKILLspam.....embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

> 3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) stand for. It stands for "I'm too lazy to type a few extra letters and too arrogant to care that not everyone can remember all the silly abbreviations". Hmm. Must be Olin... :-) In addition, these are largely "noise phrases" that add little meaning to the actual message, but would be present in conversation. They're "verbal cues for a non-verbal medium." TTYL == Talk To You Later, IMHO == In My Humble Opinion, IMO == In My Opinion, IMNSHO == In My Not So Humble Opinion (sometimes I actually take care to notice the difference between these. There can be quite a different meaning...) IIRC == If I Recall Correctly, RTFM == Read The Manual, AFIAK == As Far As I Know. I usually just skip over this crap when reading, especially if the poster wants something from me rather than the other way around. And you usually won't lose much meaning by skipping over them... The presence of many such abbreviation certainly means that the discussion is "conversational", rather than presentational or formal, I think. Messages containing technical info along with conversational idioms would be somewhat less trusted than a more formal written style. > 5. What does it mean to have an embedded processor?. An embedded processor is one that is built into something for performing a particular dedicated task. The end user doesn't have access to the processor to run arbitrary programs. > Is the processor in my washing machine embedded? Yes. > Is the one in my PC embedded? No. However, your entire PC could be "embedded" in some other application (say, a console monitor for a collection of network servers), at which point it (the whole computer) WOULD become an embedded system - there are certainly "embedded operating systems" aimed specifically at PC compatible hardware. BillW -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

part 1 519 bytes content-type:text/plain; charset=us-ascii (decoded quoted-printable) Justin Richards wrote: <snip> > > 3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) stand for. Try this link for a rather lengthy list of Internet acronyms. http://www.netlingo.com/emailsh.cfm -- Mike Werner KA8YSD | He that is slow to believe anything and | everything is of great understanding, '91 GS500E | for belief in one false principle is the Morgantown WV | beginning of all unwisdom. part 2 233 bytes content-type:application/pgp-signature (decode) part 3 105 bytes -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

> > 3. What does TTYL, IMHO, FAIK, AFAIK (and any others I may run into) > stand for. > > It stands for "I'm too lazy to type a few extra letters and too > arrogant to care that not everyone can remember all the silly > abbreviations". Personally, I find the abuse of acronyms in the Engineering field to be horrific. That's why I joined the AAAAA (American Association Against Acronym Abuse) -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu