Hey, I get the impression that my question has not come across properly. I will use a regular stereo audio signal. One track contains music, speech and other normal sounds. The other track I want to use to record commands with which I can move servos, lights, etc. At first I thought to do this with DTMF but the MT8880 has died. Then I fiddled with the TCM3105, an old-fashioned modem chip, but that didn't work either. I then read something about PW application and hence my question. I've been messing around with PICs for a long time, but because I'm purely mechanical by nature, I have to limit myself to what I called LEGO work. You make the stones and I make grateful use of them. regards Hans
Op zaterdag 26 februari 2022 om 07:41:46 UTC+1 schreef vasile: > Rob, obviously will work. :) But it would be weird to use a bunch of > external analog electronics. > BTW, with a PIC you can do a class D amplifier... what perhaps Hans > wanted is not far away: sampling and then digitizing via PWM. > Other choices are possible as well. Success on any variant you'll choose! > > On Fri, Feb 25, 2022 at 7:58 PM Rob CJ <[email protected]> wrote: > >> Hi Kiste, >> >> The reason that I think it still might work is because - what I mentioned >> previously - is that my Apple II I had built in the past also just worked >> with tones to store data (at that time only games 🙂). >> >> I copied a pice of the casette interface of the Apple II schematic >> diagram I found on the internet. What you see is that with an opamp the >> audio is input signal is converted to a digital signal and the rest of the >> processing is done in software. There is no special chip on the board to >> process this data stream. >> >> Also the data out is just a direct output of a flip-flop with some >> resistors to reduce the signal outpt but not even a low pass filter. >> >> The variations in cassette speed will result in a variation of the tone >> so if I use a tone range to detect the right tone it might work. >> >> Kind regards, >> >> Rob >> >> >> >> ------------------------------ >> *Van:* [email protected] <[email protected]> namens hans < >> [email protected]> >> *Verzonden:* vrijdag 25 februari 2022 16:20 >> *Aan:* jallib <[email protected]> >> *Onderwerp:* Re: [jallib] PWM serial audio transmission >> >> >> Hi Vasile, >> >> In my time a birth was still followed by a placenta, nowadays an iphone >> comes after. >> >> A long time ago I was infected by Wouter, Jal is even more persistent >> than corona, see http://www.voti.nl/setalk/n_index.html >> >> >> >> regards Hans >> >> Op vrijdag 25 februari 2022 om 13:34:14 UTC+1 schreef vasile: >> >> Hi Hans. Congratulations for your young mind! There aren't many people >> programming at your age. >> You are a great example! >> >> On Fri, Feb 25, 2022 at 10:16 AM hans <[email protected]> wrote: >> >> Hi Vasiele and others. >> I was born before the last world war and I suspect most of you after it. >> I hope it stays that way!! >> Great, I can study today again. Thank you. >> >> Op vrijdag 25 februari 2022 om 06:58:52 UTC+1 schreef vasile: >> >> Kiste, not only the ZX81 but Sinclair Spectrum and most of it's clones >> did the same. >> The biggest problem was the tape speed variation (among the volume >> variation which was corrected in romanian clones -and we had more than any, >> I recall 5 different types). >> >> Hans, on the actual PIC18 series on which JAL works ( presuming you will >> do with JAL) you might have some sampling speed issues. You need at least >> 7.5us for an ADC sample and according to Nyquist theorem you need not 2x ( >> which is pure theoretical) but at least 4x faster sampling than maximum >> frequency you are recording. >> After your AD is sampled, the PWM is not an issue, but you might >> experience a small delay between real recorded speech and the PWM filtered >> one. >> If you plan to add voice for your puppet, then limiting to 4KHz may be a >> good choice. >> >> best wishes, >> hopefully not WW III, but in pace for playing nice... >> >> On Thu, Feb 24, 2022 at 10:38 PM 'Oliver Seitz' via jallib < >> [email protected]> wrote: >> >> Hi Rob, >> >> connecting two PICs is not like an audio recording. Better connect the >> pic to your soundcard to record and then playback, that way you'll get >> something similar to a tape recorder. >> >> The difficulties when using audio equipment are (at least): >> >> - only alternating current is transmitted >> - the volume is never exactly the same >> - the frequency range is limited to like 100Hz-10kHz >> - the line level voltage is less than 1V >> >> Reading should be possible by most PICs which have comparators. Only a >> resistor is needed, then you can detect zero crossings. >> >> The Sinclair ZX81 used audio equipment as storage. A burst of three >> oscillations coded a zero, five coded a one. The output was low-pass >> filtered. You usually had to try loading a program several times, slightly >> adjusting the volume, until you got lucky. >> >> Greets, >> Kiste >> >> Am Donnerstag, 24. Februar 2022, 19:56:01 MEZ hat Rob CJ < >> [email protected]> Folgendes geschrieben: >> >> >> Hi Hans, >> >> If I understand you right the only thing you want to do is to record a >> signal or a sequence of signals on a casette player that can be used to >> trigger something when the recording is played back right? >> >> If my initial suggestion would work - which may work since I have the >> idea that my Apple II did more ore less the same thing - I could give it a >> try to do a proof of concept. >> >> I may have a the problem that I do not have a casette recorder but I >> could fake it by just connecting two PICs to see if that works. The final >> test could then be done by you. >> >> Which PIC type are you using? >> >> Kind regards, >> >> Rob >> >> >> >> ------------------------------ >> *Van:* [email protected] <[email protected]> namens hans < >> [email protected]> >> *Verzonden:* donderdag 24 februari 2022 17:07 >> *Aan:* jallib <[email protected]> >> *Onderwerp:* Re: [jallib] PWM serial audio transmission >> >> Another piece of text: >> So far I've done everything with MIDI. I used one midi channel for the >> actions with a general command type. Then 2 data, one for the device nr >> (16) and one for the command. (0-128) >> This has worked well for years, but it does require a complete MIDI sound >> package. >> >> Op donderdag 24 februari 2022 om 16:55:46 UTC+1 schreef hans: >> >> Hey , >> I have tried a circuit with an MT8880 but the ICI has failed. I did hear >> the 16 tones, but when I wanted to receive them, the chip gave up the ghost. >> In theory I understand your suggestions well, but developing something >> like this is not easy for me. I'm just a LEGO builder. >> regards >> Hans >> >> Op woensdag 23 februari 2022 om 19:30:37 UTC+1 schreef [email protected] >> : >> >> Hi Hans, Kiste, >> >> You can still by DTMF decoders and I assume also DTMF encoders. Just look >> at for example Aliexpress and type DTMF. >> >> But another suggestion. Many, many years ago I had built an Apple II and >> I used cassette tapes to store and load games which was using tones >> generated by the Apple II itself using two tones, one for high, one for low >> and one as a lead-in tone (not sure in the lead-in tone was another tone) >> to synchronze the start of the recorded program. You would not need this >> lead-in tone in your case >> >> So I think it may not be that complex: >> -) For recording on casette, generate this dual tone by the PIC via PWM >> or maybe it is also sufficient to generate one tone in case of a 1 and no >> tone in case of a 0 but I think this will be less reliable. >> -) For playback, measure the length of the recorded PWM tone. If is is >> within a certain range you accept it as a one and in case of two tones the >> lower tone could be zero and the higher tone is one. >> >> As long as the tone frequency is not too high, I think this could work. >> >> A more advanced solution would be to use a phase locked loop (PLL) but I >> am not sure if it will work. The PLL locks to the input signal so the >> voltage that controls the oscillator goes up and down to follow (lock on >> to) the input signal and this oscillator voltage signal could then be used >> by a comparator of the PIC to detect a high or low tone. You can also use >> the oscillator of the IC to generate the two tones by controlling the >> oscillator voltage by the PIC. A typical IC for that is the HEF4046. I have >> used this IC many many years ago too. This solution may be bit over the top >> since you only want a kind of trigger signal >> >> But maybe the first solution is more doable. Just give it a try. >> >> Kind regards, >> >> Rob >> >> ------------------------------ >> *Van:* 'Oliver Seitz' via jallib <[email protected]> >> *Verzonden:* woensdag 23 februari 2022 09:58 >> *Aan:* [email protected] <[email protected]> >> *Onderwerp:* Re: [jallib] PWM serial audio transmission >> >> Hi Hans, >> >> 20 years ago I would have suggested using DTMF, but the decoder chips are >> rare these days... >> >> PIC controllers include various peripherals which can be used to encode >> and decode DC-free signals (which, apart from the frequency below, say, >> 10kHz, is the requirement to be recorded as audio). On/off keying or >> frequency shift keying are the easiest, I think. Which chips are you going >> to use? >> >> Greets, >> Kiste >> >> Am Mittwoch, 23. Februar 2022, 09:15:43 MEZ hat hans < >> [email protected]> Folgendes geschrieben: >> >> >> Hello everyone, >> I have been trying for a long time to place a serial signal on one track >> of an audio recording which I can read afterwards. To make all kinds of >> things happen at the same time as the audio is played. I have now tried to >> do this with the old modem system ( TCM3105) but it failed hopelessly. I >> read that there are also systems to do this using PWM. 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