Abraham Lincoln said "If you give me 8 hours to cut down a tree, I will spend the first 6 hours sharpening the axe". I share your impatience, I too, want some "instant gratification" on my projects and the level of wasted time and materials are the best indicators of my success and failure. I generally choose the path of examining the working projects of others and plagiarizing their work and do sometimes get lucky enough to build a working project without fully understanding everything but not often. Asking for help here is a good start but bear in mind you may have taken a step that you are not yet prepared to finish. OTH, someone else said "A man's reach should exceed his grasp". In any case, keep it up, I enjoy following your journey. Considering your school plans, this may be the last opportunity for self guided study for many years! One more quote: "May the force be with you!" John Ferrell W8CCW "Extremism in defense of liberty is no vice, and moderation in pursuit of justice is no virtue." -Barry Goldwater "You don't get harmony when everybody sings the same note." -Doug Floyd ----- Original Message ----- From: "solarwind" To: "Microcontroller discussion list - Public." Sent: Wednesday, June 24, 2009 1:59 AM Subject: Re: [PIC] Very simple operating circuit > On Wed, Jun 24, 2009 at 6:57 AM, solarwind wrote: >> On Wed, Jun 24, 2009 at 5:25 AM, Russell McMahon >> wrote: >>> Very simple - yes. >>> Operating - sometimes, maybe, depending on assumptions which may have >>> been >>> made but which are not shown on the diagram. >>> >>> Not showing all assumptions made makes it hard for people to provide >>> useful >>> comment. (Putting SOME of them in an added list is a good start but >>> showing >>> them on the circuit even better). >>> >>> Re other query re capacitor size - you need to read the reasonably >>> extensive >>> prior discussions on decoupling capacitors or look at a good web >>> reference, >>> of which there will be thousands. The "how big should a capacitor be" >>> question is often asked and almost as often answered. Having somebody >>> tell >>> you it's not too crucial (it's not) is not a substitute for looking >>> around >>> at what is done and learning why. As 'another list member' pointed out >>> recently, lack of understanding and proper treatment of decoupling >>> capacitors is a major source of probelms. I don't think he put it quite >>> that >>> way :-).And, more caps often don't hurt. Avdd to Avss may benefit from >>> such. >>> or may not, sometiomes. >>> >>> Hardware terminating /MCLR in any of the several approved manners is >>> generally held to be superior to disabling it in software, where that is >>> an >>> option. (Where it's not an option then doing it in hardware is a >>> *REALLY* >>> good idea :-) ). >>> >>> With such a capable device it would be usual to use an external crystal >>> or >>> clock source. ie if you are using a DSPIC then it won't be long before >>> you >>> would like the clock frequency to be moderately accurately known and >>> stable. >>> Providing for a crystal and not using it at first works better than not >>> providing for it and wanting to use one. >>> >>> Diagram and reality never correlate 100% but note that it may be better >>> to >>> run all ground traces directly to the common ground point than to chain >>> them >>> as shown. AVss especially is provided separately for good reason. This >>> being >>> a dsPIC you may care more in this case than in many others. Ground >>> currents >>> flowing in the common ground path will appear as signal to the analog >>> circuitry if built as shown. Gargoyle knows all about this. For many >>> applications this may not make a vast difference but as it's as easy to >>> do >>> right as wrong you might as well get in the habit of doing it >>> pedantically >>> against the day when you need to care. >>> >>> You may wish to group some ISP pins on a header. >>> >>> Beyong minimalist, but you MAY want to provide options for SIP resistor >>> packs of high resistance pull up/downs for some pins to make the >>> software >>> rogours less demanding. If you are well disciplined at ensuring the >>> software >>> matches the hardwrae (nothing floats without a pull [up|down], all >>> unterminated pins are outputs, analog functions are disabled when not >>> used >>> and allowed for appropriately in hardware, ...]. >>> >>> ie it's just another processor and indeed just another IC whose pins >>> must be >>> terminated correctly as per spec sheet - but it has a bit wider >>> definition >>> of "correctly" than say a 74HC14 (gotta love those Schmitt imputs). >> >> Wow - I just want it to work :( >> >> For my PIC18F2620, all I did is hook up ICSP pins, UART pins, a >> decoupling cap and it worked. I'm asking (in a similar fashion) how to >> quickstart with the dsPIC with minimal fuss and minimal components. >> That is, other than 3 caps, would anything else be REQUIRED to get it >> up and running? (I have PICKIT2 hooked up to ICSP and UART lines to >> MAX233A) >> >> I ask because I see all these new pins (AVSS, AVDD, VDDCORE) that I >> don't really know what to do with... Sure, there's the datasheet, but >> it's so BIG, that it's easy to miss something. Also, for such a simple >> quickstart circuit, I was hoping someone could provide, short, concise >> answers. It shouldn't be too much of a problem since the circuit IS >> simple and it's just to get started (program hello world code and see >> it on my terminal). >> > > Don't get me wrong, your long, detailed explanation is much > appreciated, but for someone who's diving into a very different chip > for the first time, it can be overwhelming. > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist