You can tune it, too, see e.g. this project:
Change R1 for tuning or use a potentiometer for it.
-- Frank Buss, http://www.frank-buss.de piano and more: http://www.youtube.com/user/frankbuss
Jan Panteltje expounded in news:ike6t1$nei$ snipped-for-privacy@news.albasani.net:
..
You just need to add some storage on the mother ship.
Anything that requires software and a programming cycle, adds a lot of time for a one-off hobby project. Soldering in a 555 seems an order of magnetude simpler, IMO. Very simple to debug also. Mind you, a synth sounds like the wrong application for it (which is perhaps your point).
If your "Ada" book (note capitalization) is prior to '95, it is probably not worth keeping anyway. But Ada is still alive and well, and I've used it on AVR. See:
MS crap has a lifetime about as long as an isolated quark.
Nuke it.
The 555 is a good, cheap, simple IC for the right application. I'm not sure I'd build a synth from it, though.
Warren
A PIC can only be used with an RC-oscillator for the lower frequencies. For a PIC16F84 the maximum recommanded frequency using an RC combination is some
10MHz. As the machine cycle is 4 clocks and the program will require at least 4 machine cycles, the maximum oscillator frequency will be about 625kHz. As for the freqency only, the original 555 can be beaten here, but CMOS versions of the 555 can do up to 3MHz. Another drawback of the PIC in this mode is its sensitivity for supply voltage and temperature variations. Of course, the importance of this drawback depends on the application. As always.petrus bitbyter
I haven't examined the MSP430 with an eye to producing a range of frequencies like this, but it possesses a highly configurable DCO. Together with a 32kHz crystal input (very low power), the DCO could rely upon the crystal for periodic updates to hold long term precision against the crystal's accuracy and do that with very many cpu clock rates which could then slide around over a great range permitting the generation of nearly any frequency with knowable variation relative to the 32kHz crystal accuracy. The DCO can be slewed around over at least two orders of magnitude in clock rate, which suggests more than enough flexibility. The timer outputs are quite capable and since the DCO can be at least
16MHz (guaranteed, and as much as 26MHz not guaranteed), quite high square wave output rates are achievable. The 3MHz rate seems doable. Without the crystal, each processor does have some calibration values that might also be used. At least a calibrated 1MHz and calibrated 16MHz value. Not sure how all that would work, in detail, though using those for linear estimation suggests itself. So conceptually, its workable too. I may play with this on the LaunchPad to see what can be achieved, this coming month.Jon
On a sunny day (Tue, 1 Mar 2011 00:12:26 +0100) it happened "petrus bitbyter" wrote in :
bit-eter, you have very basic misunderstanding of the PIC architecture. Even many of the simplest PICs have one or more analog comparators. With those you can make a supply voltage independent oscillator clone of a 555. Not only that, by putting some PIC outputs in parallel you can drive more current than a 555, not only that the PICs will do all this at a higher frequency. For a clue, I have done video sync separation, line counting and black level re-insertion with a 12F PIC, the LC meter on my site uses a analog comparator as precision LC oscillator, etc etc, the gamma spectrometer uses the analog comparator to detect PMT pulses, etc etc.. It all boils down to the fact that you do not have enough experience with PICs, or maybe software design for those.
"Jan Panteltje" schreef in bericht news:iki9eu$m90$ snipped-for-privacy@news.albasani.net...
Keep in mind that I compared 555s with the 8 pin PICs PIC12F675 and PIC12F629 in a reaction on the Elektor article. I did not mean to treat the subject at length. Even If I would, I will be limited as I do not know *all* about both of them.
Though I know about the comparators, I don't know the maximum frequency they can be used for an oscillator. As an aside, if you use a PIC or a 555 only as a comparator both may be overkill. But as always, it depends...
From the top of my head, the PICs mentioned can do 25mA output current. For an 8 pins PIC, 5 parallel outputs will make 125mA. Which is less then the
200mA of a standard 555 but more then the 100mA of the CMOS version.Following your posts about PICs I immediately admit you're vastly more experienced then me. If only your drawings... :)
petrus bitbyter
"Jon Kirwan" schreef in bericht news: snipped-for-privacy@4ax.com...
I too got the Launchpad and installed both software and hardware. But the Quicklaunch took much more time then I have available so it rests for the moment. IMHO the manual is not very clear. Apparently written by someone who knows the stuff and jumped over some - for him - obvious steps that are not obvious for me.
petrus bitbyter
I got things working okay. I also have a slight advantage here. I've written code for the MSP430 to synchronize the DCO against a 120 Hz (zero crossing 60Hz) power line event. I could cause the processor to closely synchronize the DCO clock rate so that a simple computation could be used in computing the relative phase for triggering a TRIAC, for example. And I could chose at compile time which kind of multiplier I wanted for the DCO relative to the zero cross signal. Worked beautifully. However, it did take me some time and some notes in order to carefully ferret out how to interpret the DCO operation, correctly. Particular attention was needed to details about processor variation across parts, time, and temperature and how the various sections worked toegther. It's all there, but not in tidy form. I had to fill a few pages of a notebook before I felt I finally understood all of it. So that's why I have a small advantage here. Been through much of the learning, already.
Jon
On a sunny day (Tue, 1 Mar 2011 11:15:42 +0100) it happened "petrus bitbyter" wrote in :
Thank you, I grew up with writing machine code in zeros and ones. So from that point of view, PIC, however small, is a big castle with increadble resources, Yes I was not only thinking 12F, but also PICs with more pins, that then allows optional nice things like driving a LCD. As prices of small text LCDs are now less than 5 Euro... So then you can actually see the frequency of your oscillator, the supply voltage, anything else at hardly any extra cost. Drawings are availble upon request in the original higher resolution format. A braille version is not planned ATM ;-)
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