PIC scope test1
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From: John Larkin on 16 Mar 2010 10:07 On Mon, 15 Mar 2010 16:48:31 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >PIC scope test1 > >This is the maximum aquisition speed I can get out of a PIC 18F14K22, >10 kHz sinewave: > ftp://panteltje.com/pub/PIC_18F14K22_scope_10kHz_img_1876.jpg > >Not bad at all, if you realise it is 127 dots for about 5 periods. >With 100 uS per period the display width is about 500 uS, >that makes 500 uS / 127 = 3.9, say 4 uS per sample, or 250 kHz from the ADC. > >Trigger is rock solid too :-) >Input is line level audio. > Cool. The first PC scope I did was an IBM 1401 with the waveform plotted on a line printer. Home-made ADC. John
From: MK on 16 Mar 2010 10:26 "Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> wrote in message news:hnntn5$lge$1(a)news.albasani.net... > On a sunny day (Tue, 16 Mar 2010 08:12:12 -0000) it happened "MK" > <mk(a)nospam.please> wrote in <2MGdndaBUab9oALWnZ2dnUVZ7sednZ2d(a)bt.com>: > >> >>"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> wrote in message >>news:hnlod6$c0v$1(a)news.albasani.net... >>> PIC scope test1 >>> >>> This is the maximum aquisition speed I can get out of a PIC 18F14K22, >>> 10 kHz sinewave: >>> ftp://panteltje.com/pub/PIC_18F14K22_scope_10kHz_img_1876.jpg >>> >>> Not bad at all, if you realise it is 127 dots for about 5 periods. >>> With 100 uS per period the display width is about 500 uS, >>> that makes 500 uS / 127 = 3.9, say 4 uS per sample, or 250 kHz from the >>> ADC. >>> >>> Trigger is rock solid too :-) >>> Input is line level audio. >>> >>> >>Hello Jan, >> >> >>Looking at your PIC scope I can't help but remember Dr Johnson's comment >>to >>Boswell on women preaching: >> >> Johnson: "Sir, a woman's preaching is like a dog's walking on his hind >>legs. It is not done well; but you are surprised to find it done at all." >> >>Jan - why a PIC ? > > I wrote the graphics controller code, x, y plot for this LCD in PIC 18 > ASM. > The PIC has an ADC, why not try scope? Have 3 free input pins :-) > Took only an hour to program the scope routine. > > I also have a Spartan2 connected to a 30 MHz video ADC, > uses internal RAM and has a serial and UDP interface, > but it has a character display :-) > I could hang the graphics LCD with PIC on its serial out too. > > PIC scope code is just a library building block, like the graphics code. > PIC is more powerful then you think, runs 64 MHz clock, 18F has some nice > instructions to move data in RAM. > Just fun to do some asm. > > And I can think of many applications that will have no problem, > hoe about a live mains waveform monitor? Mains spike detector? > Hart beat display? > Not all has to be GHz for it to be useful you know, on the contrary! > > And PIC is cheap, easy to program, available everywhere, seems reliable > too. > No I do not work for Microchip :-) And hold no Microchip shares. > > Oh, and PIC uses extremely extremely and I repeat EXTREMELY little power. > Hello Jan - Don't mind my sense of humour - I appreciate your initial posting and comments. I've never really liked the PIC route - some prejudice some logic, just for comparison I'm working on a design with an STM32F ARM from their new "Value" line - 24MHz (equiv to 96MHz PIC clock), 12 bit ADC, 16k Flash, 4k RAM, 32 bit registers $0.85 (or �0.50 in our money), low power too. If I get time one day I'll try to replicate your scope. Michael Kellett
From: Jan Panteltje on 16 Mar 2010 12:58 On a sunny day (Tue, 16 Mar 2010 07:07:19 -0700) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <724vp5th3fmmpu75u42duilnlf525q6ivl(a)4ax.com>: >On Mon, 15 Mar 2010 16:48:31 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>PIC scope test1 >> >>This is the maximum aquisition speed I can get out of a PIC 18F14K22, >>10 kHz sinewave: >> ftp://panteltje.com/pub/PIC_18F14K22_scope_10kHz_img_1876.jpg >> >>Not bad at all, if you realise it is 127 dots for about 5 periods. >>With 100 uS per period the display width is about 500 uS, >>that makes 500 uS / 127 = 3.9, say 4 uS per sample, or 250 kHz from the ADC. >> >>Trigger is rock solid too :-) >>Input is line level audio. >> > >Cool. The first PC scope I did was an IBM 1401 with the waveform >plotted on a line printer. Home-made ADC. > >John Yes, I did fft display on a printer..... Like this: ********** 1000 ******** 1010 *********** 1020 *** 1030 .... I only made a home made ADC for video in 1979, it was a board full of TTL and 74121 one shots. 6 bits, but it worked, nice picture. Then somebody walked in and dropped a datasheet for a chip on my desk that did the same thing, but then 8 bits, a 'flash' converter. Too many comparators needed :-)
From: langwadt on 16 Mar 2010 13:13 On 16 Mar., 12:02, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: > On a sunny day (Mon, 15 Mar 2010 12:40:11 -0700 (PDT)) it happened GiveMeL > <pete.bergl...(a)gmail.com> wrote in > <7863c47e-99fd-4d27-932b-d912c66cc...(a)o3g2000yqb.googlegroups.com>: > > >I did a similar thing with a 18F2450 except that I streamed the > >samples to a PC via USB, at 64k samples per second. So I have > >unlimited storage =P > > Yes, unlimited storage is a nice feature. > But I am not really an USB enthusiast. > One thing I would like for my PIC scope is isolation from ground. > Important for very small signals, and also when measuring on things > that carry some volts. > > So I was thinking of using ethernet and sending UDP packets. > Packet loss on LAN is not that likely, so UDP would do. > Would take an extra chip, and not sure if I have enough memory to construct > an UDP packet. something like this has build in memory: http://ww1.microchip.com/downloads/en/DeviceDoc/39662c.pdf > And I find writing ethernet based programs on the PC in Linux much easier then > using lib USB and writing USB drivers. get something like this and you have a usb serial port and +5V http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=768-1028-ND and you can access it either as a serialport or directly > Also it means the PIC scope system can be accessed remotely, when the PC is off. > The advantage of USB is the 5 V, but already a lot hangs on the USB here. > Walwarts are only about 5$. -Lasse
From: Fred Bartoli on 16 Mar 2010 17:36 Jan Panteltje a �crit : > PIC scope test1 > > This is the maximum aquisition speed I can get out of a PIC 18F14K22, > 10 kHz sinewave: > ftp://panteltje.com/pub/PIC_18F14K22_scope_10kHz_img_1876.jpg > > Not bad at all, if you realise it is 127 dots for about 5 periods. > With 100 uS per period the display width is about 500 uS, > that makes 500 uS / 127 = 3.9, say 4 uS per sample, or 250 kHz from the ADC. > > Trigger is rock solid too :-) > Input is line level audio. > > You don't need a PIC to do that. That is, unless you want to impress customers... All that's needed is a gold leaf electroscope, a protractor, a switch and a stopwatch, or if you want to get fancy a synchronized rotary switch. -- Thanks, Fred.
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