#qi-hardware IRC log for Friday, 2011-01-14

lekernelwpwrak: http://sources.redhat.com/bugzilla/show_bug.cgi?id=326605:39
lekernelso much for your love of GNU05:39
wpwraklekernel: good old uli ... one of the reasons why glibc has been forked05:52
wpwraklekernel: well, "forked". they still track glibc, so technically, it's not a fork ;-) http://www.eglibc.org/faq05:55
kristianpaulhe dash vs bash issues :-)06:07
lekernelthat's not the point, the point is that the libc doesn't have to dictate a particular shell06:08
lekernelanother example of GNU imperialism, and then they blame Microsoft for the same thing06:09
wpwraklekernel: are you using glibc or eglibc ? in the former case, i'd strongly suggest to consider switching.06:09
wpwraklekernel: there was also a connection with the binutils. in some cases, you can get "bad" binutils if you use the official (Uli) versions.06:10
lekernelis there any non-GNU replacement for those binutils btw?06:10
lekernelfor gcc there's llvm, which is good06:10
lekernelbut it still uses the gnu assembler and linker :(06:10
kristianpaulGNU is whole OS, remenber that ;-)06:11
kristianpaulwell, you can call it imperialism06:12
wpwraklekernel: I don't know of any alternative to binutils06:14
lekernelmh... me neither... again something that would need to be addressed06:14
lekernelthe binutils code quality isn't much better than gcc's06:15
wpwraklekernel: gnu coding style per se sucks :)06:15
kristianpaulnah, and i was reading their codying style guide :/06:19
lekernelI didn't know they had a coding style guide06:21
lekernelfound it, and the first thing I read is:06:22
lekernelPlease dont use win as an abbreviation for Microsoft Windows in GNU software or documentation. In hacker terminology, calling something a win is a form of praise. If you wish to praise Microsoft Windows when speaking on your own, by all means do so, but not in GNU software06:22
wpwraklekernel: the first thing you read is the trademarks section ? ;-)06:25
lekernelwell, they put it at the beginning06:25
lekernel1 About the GNU Coding Standards06:25
lekernel2 Keeping Free Software Free06:25
lekernel2.1 Referring to Proprietary Programs06:25
lekernel2.2 Accepting Contributions06:25
lekernel2.3 Trademarks06:25
wpwrakit's just bait ;-)06:26
lekerneli'm sure they enforce it06:26
wpwraklekernel: when was the last time you saw a troll who didn't enjoy getting challenged ? ;-)07:00
qi-bot[commit] kyak: Tile: the 15 Puzzle game written in Qt4 http://qi-hw.com/p/openwrt-packages/bd5375908:32
mthlekernel: maybe you could port the BSD linker?09:47
wpwrakDocScrutinizer: can i borrow your vast experience with troublesome electronics for a moment ?10:44
qi-bot[commit] kyak: Tile: check if the puzzle is solved http://qi-hw.com/p/openwrt-packages/ca4ebe411:26
DocScrutinizerwpwrak: sure11:33
wpwrakDocScrutinizer: kewl. given a little ~2.4 GHz transmitter, set to emit an unmodulated 2.45 GHz test signal11:34
DocScrutinizerjust let me get a coffee11:34
wpwrakDocScrutinizer: the signal goes via the air to a spectrum analyzer (well, my USRP2, so it's uncalibrated)11:35
wpwrakDocScrutinizer: this it what it looks like: http://downloads.qi-hardware.com/people/werner/wpan/tst-cw/11:35
wpwrakDocScrutinizer: the interesting examples would be in the 4th row (the one with two graphs)11:35
wpwrakDocScrutinizer: ah, the signal is offset by 0.5 MHz. so it's 2449.5 MHz in the left picture and 2450.5 MHz in the right picture11:36
wpwrakDocScrutinizer: you can see that I have about 40 dB between the peak and the trouble underneath. does this look halfway reasonable so far ?11:37
DocScrutinizerwpwrak: the assumption "unmodulated" seems incorrect. Esp row 5 you seem to have *massive* modulation by pink noise11:46
wpwrakDocScrutinizer: wait .... row 4 first :)11:46
DocScrutinizer(well, maybe actual data even)11:46
wpwrakDocScrutinizer: does row 4 look acceptable for an unmodulated carrier ?11:47
DocScrutinizersame, but to a lesser extent11:47
DocScrutinizernot really11:47
DocScrutinizercould you compare to other TX hw?11:47
DocScrutinizerto rule out your RX has some intermodulatio with noise on e.g. power supply11:48
wpwrakDocScrutinizer: only to other of my designs using the same chips. they are in rows 2 and 3. they all look quite similar.11:48
wpwrakDocScrutinizer: ah .. i see what you mean. hmm.11:48
DocScrutinizerI see. What about some stupid babyphone or whatever11:49
wpwrakDocScrutinizer: don't have that. besides, it would be modulated.11:49
DocScrutinizerand check your power suplies11:49
DocScrutinizera simple babyphone wouldn't be modulated when you're hush11:50
wpwrakDocScrutinizer: oh, and my USRP2 has a resolution of only 14 bits. that would be ~42 dB.11:51
DocScrutinizeror lemme put it that way: it's modulated 0%11:51
DocScrutinizeroh, so maybe it's quantisations noise?11:51
DocScrutinizerwould make sense. You need that babyphone :-)11:52
wpwrakDocScrutinizer: the noise floor I see without any signal is about -70 dB. but i don't know what becomes of a signal.11:52
DocScrutinizerrow1 is nice but useless11:52
DocScrutinizerthere's just one way: try to 'calibrate' wit a 'known good' signal11:54
wpwrakalas, i don't have that :-( my transceiver board is only half-duplex.11:55
wpwrakof course, i could try to bounce the signal off the moon. that should give me enough time to switch from tx to rx ;-)11:55
DocScrutinizeruse an arbitrary wlan or BT or whatever is sending in roughly the same band11:55
wpwrakwlan is waaaay to wide11:55
DocScrutinizertake in account possible modulations. You still can compare what you see to what you expect11:56
wpwrakat this resolution, i just see the whole display jump up when wlan does something11:56
wpwrakthe transceiver is specified with about 48 dB between center and 2nd and 3rd harmonics.11:58
wpwrakso i think i'm at least in the ballpark.11:58
DocScrutinizeryes, that would match, though of course that'S side band, not harmonics12:00
wpwrakyup. they don't specify sidebands12:00
DocScrutinizerNB I don't think row 4 has any particular problems12:01
wpwrakgreat. that's what i was hoping for :)12:02
DocScrutinizerit just shows to some extent the same noise as row 512:02
wpwrakat least compared to what follows ...12:02
DocScrutinizerthe same pattern of noise12:02
DocScrutinizerben#3 and ben#4 are unbearable12:03
wpwraknow, row 5. that's the guru punk version of row 4. high on top of a mountain and with spiky hair.12:03
DocScrutinizerI suggest you check your VDD12:04
wpwraki tried to tame it down a little. first http://downloads.qi-hardware.com/people/werner/wpan/rework-20110112/12:04
wpwrakthen http://downloads.qi-hardware.com/people/werner/wpan/rework-20110113/12:04
wpwraki beaded VDD and also doubled the bypassing, with no effect at all12:04
wpwrakwhat did improve things a little was changing the clock voltage divider circuit12:05
wpwraknote that the rework-20110113 series is tethered. some of my rework made the board too thick to go into a ben.12:07
wpwraki'm now reworking it to make it thin again, so that i can see if the improvements remain when connecting to a regular ben.12:07
wpwraksome of the measurements suggest that a "full" ben may add some gremlins to the mix, compared to the bare pcb. may be the lcm.12:08
DocScrutinizeryou are fully aware about the principles I guess. Meassure the delta-f between center and sideband peak and you got the AM signal's frequency12:11
DocScrutinizerfor FM it's much harder to calculate and I don't really understand how to do that. I also never understood how to use those FM sythesis keyboards (DX-7 ?)12:12
wpwraki'm more concerned about the "mountain" for now. i've made the sidebands go away once by adding a small bypass to the rf feed line.12:13
wpwrakso i have about +/- 1 MHz of fairly persistent noise.12:15
DocScrutinizerWhat I'd do is: use a usual needle (or 1"/25mm wire), extend it with a non-conductive handle of at least 30cm so you can hold it without interfering with the electrical properties. Then touch all pins of your circuit, and whatch noise floor while you do that12:16
wpwrakdoes the needle connect to anything ?12:18
DocScrutinizerjust a small "antenna" to catch the noise of your environment12:18
DocScrutinizerI guess you'll find some pins that are massively susceptible to this kind of manipulation (OSC-IN ?). It's worth to have a closer look to those details in your design, maybe use a better trace layout etc for those pins.12:21
DocScrutinizerAlso I read to tried to do something to VDD by adding a 1uF. Probably worthless, better add a 1nF, maybe even several. Try different locations to add. Try a bead in VDD12:22
DocScrutinizerone thing that might give you dispair though is the fact that cheap cheesy TX circuits are susceptible to cating up noise *by the antenna*12:24
wpwraki tried a VDD bead already. didn't do anything.12:25
DocScrutinizerthere's not much you could possibly do in that case, except reducing ambient noise (shield converters, e.g. of LCD backlight, etc)12:25
DocScrutinizerif you want you may toss over the URLs to schematics pdf, and layout pdf12:26
wpwrakthe antenna is grounded for now. (when i go tethered, i cut the antenna a bit and solder an U.FL connector that grounds the antenna)12:26
wpwrakschematics are here: http://projects.qi-hardware.com/schhist/atusd/12:27
wpwraknow that i changed the clock divider. it's now 5.6 k : 1 k resistive, followed by 1 nF DC block.12:28
wpwraki tested the parameter sensitivity of the DC block - 10 pF and 100 nF yield basically identical results.12:28
DocScrutinizeraaah, I seem like recalling there were problems back in good ole' '76 with CB (27MHz), the antenna when detuned could cause the TX power drivers of the walkietalkie to emits all kinds of nasty sideband and harmonics12:28
wpwrakalso, dropping the resistive pair by one order of magniture (560 R:100 R) doesn't change the result.12:29
wpwrakthe 201101013 series eliminates the antenna from the equation :) it all goes straight to the USRP2. well, through a 10 dB attenuator. don't want to fry the LNA :)12:30
wpwrak(although it's probably fine with the meager 3 dBm i can throw at it)12:31
DocScrutinizerwerner, are you *sure* the AT86RF231 doesn't have an always-modulated RF signal? like filling in soem padding when no data is transmitted12:33
wpwrakit's in "continuous wave" test mode12:33
wpwrakbesides, the "row 3" result, with 40 dB separation, is with the same chip12:34
DocScrutinizerCW doesn't necessarily mean no modulation12:34
DocScrutinizeraah, ok12:34
wpwraknow .. let's try joerg's bad finger ...12:36
wpwraktouching XTAL1 directly crashes the chip. well, i had that before with the scope probe.12:37
DocScrutinizerdon't stab anything :-P12:37
wpwraktouching before the blocking cap raises the noise beyond +/- 1 MHz by about 5-10 dB but doesn't affect the central hill.12:40
DocScrutinizerthe blocking cap would obviously effectively filter out oise <1MHz12:42
wpwrakmaybe .. don't know the input impedance of XTAL112:43
wpwrakbut the more it filters, the better ;-)12:43
wpwraktouching VDD doesn't seem to have much of an effect. btw, neither does my body hovering some 10-20 cm over the circuit12:44
DocScrutinizeraaah, always hard to follow what you do, unless given component names. The whole thing is externally clocked? Yuck! Check that clock for jitter and noise. Consider using a local xtal instead, even if only for ruling out it's the ext clck that is polluted12:46
wpwrakbtw, the sidebands vary by around 5 dB while the "hill" remains constant most of the time. sometimes everything jumps, but that may be some wlan again (i've shut down mine)12:46
wpwrakyes, local xtal will be the next thing to try. the USB boards (row 1-3) all have a crystal.12:47
wpwrakof course, a crystal is something i'd really love not to have on the bom :)12:47
wpwrakbesides, it would make the board larger. yet another reason to dislike it.12:48
DocScrutinizerusing external clocks for TX is usually a bad idea, unless you have a really high quality known good master clock generator somewhere in your circuit12:48
wpwrakthe ben's clock should be accurate enough. also, at accutracy of at least the long-term frequency (measured over minutes) is more than sufficient12:49
DocScrutinizerif you must use this external clock, then FILTER it, use R-C bandpass of 3rd order, use L-C tuned to the freq of clock12:49
DocScrutinizerit's all about jitter and noise12:50
wpwraki tried to use my function generate to provide an external clock, but that didn't go well. see the two "combs" around the middle of http://downloads.qi-hardware.com/people/werner/wpan/rework-20110113/12:50
DocScrutinizerthe long cables and external gear introduced lots of noise12:51
wpwrakyup. if we discount the sidebands really close to the center, then the "hill" dropped by 5-10 dB, though. but i'm not sure if this is a meaningful interpretation.12:52
DocScrutinizerIt's quite obvious now: you need a better clock12:54
wpwraki tried to find any disagreement between the external clock input and the transceiver's clock output (it can output the divided input clock), but that wasn't very conclusive because i couldn't get a good trigger12:54
wpwrakit's the two blurry curves on http://downloads.qi-hardware.com/people/werner/wpan/rework-20110112/12:54
wpwraknow, what would be the best way to go about this ?12:56
wpwrak(poking around some more with your "bad finger". nothing really responds to it)12:56
DocScrutinizerget an xtal :-D12:59
DocScrutinizerI know I know12:59
wpwrakxtal doesn't convey the cool simplicity i'm after12:59
wpwrakany simple LC filter that could help ? right now, i have 1 C and 2 R in the clock path. i should be able to add 2 more components.13:01
wpwrakmaybe 3 if i really squeeze things.13:01
wpwrakof course, if the filter does the DC blocking too, that's one more "free" component13:02
DocScrutinizerL-C with high Q, loosely coupled to clock source, might do. Have fun tuning it ;-D13:07
DocScrutinizerThat's beyond my competences13:07
wpwrakgrr :)13:07
wpwrakthat would be a bandpass then ?13:08
DocScrutinizerthat would be an L-C parallel resonator tuned to the 16MHz it shall provide, with high Q, means it shall keep oscillating for >> 1/1Mhz, i.e. 50% of sine amplitude @ 16MHz after nn microseconds. Maybe undampened by feedback of XTAL2 to the LC with attenuation so it just doesn't start oscillating itself13:12
DocScrutinizerthen gently feed energy from external clock, so an oscillation builds up after several nn microseconds13:13
DocScrutinizermuuch more icky to design, to tune, to debug. And BOM won't get any nicer13:14
DocScrutinizercompared to a cheap XTAL13:14
wpwrakthere are no xtals that are small and cheap :-(13:17
Action: DocScrutinizer pries open his BT usb stick13:17
wpwrakeven the 3.2 x 2.5 xtal i'm using is still around usd 0.6 @ 10013:18
wpwraknew data point at the bottom of http://downloads.qi-hardware.com/people/werner/wpan/rework-20110113/13:20
wpwrakthis is back over the air, with an external antenna13:20
DocScrutinizerhmm, this BT stick has a 5 * 3.1mm "16.000 H.ELE.7L"13:21
wpwrakthe sidebands almost at the center are probably just antenna tuning. in fact, as it watch it, they're merging into the center13:21
wpwrakthat's not 7L that's XXXL ! ;-)13:22
DocScrutinizerwell, at least that one is nicely low-profiled13:23
DocScrutinizereven the nearby chip is thicker13:23
wpwrakupdated 20110113 again, with the merged sidebands13:23
wpwrakabout 25 dB between peak and noise floor. getting close :)13:23
wpwrakmy goal is to get something around 30 dB (without crystal)13:24
wpwrak802.15.4 has some requirements on the channel width, but i think i comply with them even with the original (horrible) circuit13:25
DocScrutinizertry using R-C bandpass in clock13:25
wpwrakokay, that should be easy13:27
wpwrakhuh ? not13:28
DocScrutinizer1st 4 are the highpass, followed by a lowpass13:28
wpwrak.   R     C13:29
wpwrak(hmm, i wonder how this looks)13:29
wpwrakyou have about twice the number of components i can comfortably fit :-(13:29
DocScrutinizerwell, but then my circuit is twice as good :-D13:30
DocScrutinizeryou may get away with a single RC for high and low13:30
wpwrak(single RC for high/low) how's that ?13:31
DocScrutinizeror one RC for lowpass and 2 RC for highpass13:31
DocScrutinizerdepends on how bad your clock is contaminated. And nota bene R-C filters won't fix jitter13:32
wpwraki think i'll try RC+RC. that still looks reasonable. for anything more complex, i'd basically poke around blindly, because any measurement would be likely to derail things13:35
wpwrakhow wide should i make the pass band ?13:35
DocScrutinizeralso consider finding a bead that has a resonance peak @16MHz13:35
DocScrutinizer(wide) -013:35
wpwrakso far, beads have done absolutely nothing. (don't have a large choice of them, though)13:35
DocScrutinizerI have a complete component book, with maybe 200 different breed13:36
DocScrutinizerI'l have a look13:36
DocScrutinizerplacing such a bead instead of R2 in your link above could increase filter quality noticably13:37
wpwrakthe beads i have are (digi-key number) 587-1866-1-nd, 587-2419-1-nd, and 587-1926-1-nd. plus a few 490-4012-1-nd arrays.13:39
DocScrutinizeryou'd calculate with R2 = bead's off-resonance impedance13:39
wpwrakhmm, that's usually something very close to 0 Ohm13:40
wpwraki understand what you're saying. not sure about that :)13:41
wpwrake.g., consider these: http://www.yuden.co.jp/ut/product/pdf/mlci08_e.pdf13:41
wpwraklet's say BKP1005HS330. that one has 33 Ohm at 100 MHz. close to 0 Ohm at DC. or would i use the impedance at the clock frequency, 16 MHz ? that would be something like 15-20 Ohm.13:43
wpwrakor maybe the BK1608HM601, with 600 Ohm at 100 MHz ?13:44
DocScrutinizernah, beads usually have something like 33R or 100R, for AC. DC isn't relevant here13:45
wpwrakbut isn't that the resonance impedance ?13:46
DocScrutinizeralas all my FBM-11 beads here have a peak next 100MHz, or maybe 30MHz (one of them)13:46
DocScrutinizernone has a usable characteristics for 16MHz13:47
wpwrakyup, here too13:47
DocScrutinizerFBM-11-321611-202: R @16MHz: ~1000R,  @10:500R,  @40:2700, @2:~10..50 (too small on this diagram)13:53
wpwraknot from digi-key, i suppose ?13:54
wpwrakat least i can't see it there13:54
DocScrutinizerR(DC): 1.2ohm;  I(DC):100mA; size: 3.2*1.6*1.1mm13:55
wpwrak(3.2*1.6 mm) does this come with a SUV for transportation ? ;-)13:56
wpwrakwow. 1206. and i was cursing those bulky 0603 beads :)13:57
wpwraknaw, that's waaaay to big.13:58
DocScrutinizeryou won't get magic ferrite13:58
DocScrutinizeranyway, I guess I can't help any better13:59
DocScrutinizeras mentioned above, that's way beyond my competence14:00
DocScrutinizergood luck14:00
wpwraksmall inductors would be an option14:00
wpwrakbeads don't seem to fit well in general. i guess for such special needs, one would use a T or Pi filter instead of a bead.14:01
wpwrakwell perhaps just RC then. if that doesn't work, then with a bloody crystal.14:03
wpwrakfor RC, how large a pass band would you recommend ? or should i define it in terms of the attenuation of the clock frequency ?14:04
wpwrakand pass band symmetric around the clock frequency ?14:04
DocScrutinizerI'd guess you want especially low freq cutoff. I don't expect freq>16MHz to introduce much noise relevant for clock generation. So calculate R-C for -6dB @ 16MHz (i.e f0 >clock). For the lowpass you probably are free to choose anything that does a semidecent job at attenuating harmonics14:12
DocScrutinizerI'd even consider a 2nd order highpass raher than a bandpass, with a given number of components14:13
DocScrutinizerbut as mentioned before, all that won't help to kill jitter14:14
DocScrutinizerjitter in turn will cause FM, which easily creates the sidebands you see14:14
wpwraka high-pass may at least kill jitter caused by noise riding on the signal and pushing the edges14:14
DocScrutinizerthat's the idea14:14
wpwrakhmm, the noise is only about +/- 1 MHz14:15
DocScrutinizerso expect your noise on clock being in same freq range14:15
wpwrakof course, that's after the clock input circuit and after the PLL. cause and effect are a bit distant here ...14:16
DocScrutinizerthough maybe not, it's a complex circuit, including a PLL to upscale clock I guess14:16
wpwrakyep :)14:16
DocScrutinizerdoes the PLL have any external components? like R, C?14:17
wpwraknope. it's all inside14:17
DocScrutinizerhmm nope14:18
DocScrutinizerthe worse effect you'll see of any jitter14:18
wpwrakactually .. if i go for -7.5 dB at 16 MHz, then i don't need a divider. one component saved :)14:20
DocScrutinizerthe PLL probably is *very* fast, and each single 16MHz clock edge with a tiny bit of jitter causing massive FM noise on TX14:20
qi-bot[commit] kyak: Tile: small fix. http://qi-hw.com/p/openwrt-packages/e5d083714:24
wpwraklet's just hope the ben doesn't jitter much :)14:24
DocScrutinizerooh, btw: werner, you are feeding the clock via a long cable, from mainboard to atusd? That probably won't pan out anyway, without using symmetric feed and a balun at both ends14:28
wpwrakabout 7 cm in total14:29
wpwrak(cpu to transceiver)14:30
wpwrakmy board sits in the uSD slot14:30
DocScrutinizermight work14:32
DocScrutinizerkeep trace pseudo-symmetric to a parallel ground though14:32
DocScrutinizerand of course impedance tuned14:34
DocScrutinizeryou don't want any ringing and/or standing waves on that line14:35
DocScrutinizerplus you want it properly shielded, also against crosstalk from traces next to it14:35
wpwraki have no control over what's going on in the ben ...14:36
wpwrakSD clock is between the power lines, so this helps14:36
DocScrutinizerthat might be a problem then, disqualifying this clock signal for use as a TX source, with high requirements for S/N and jitter free14:37
DocScrutinizerSD clock? Hell! that's by design not meant to be jitter free14:38
DocScrutinizerhonestly, go for XTAL14:38
DocScrutinizerI thought you're using a master clock source, like CPU XTAL or sth14:40
DocScrutinizernot something generated in a SD card interface, and never meant to be jitter free or anything you'd want to see for TX clock source14:40
wpwrakwhy would the SD clock have more jitter than the master clock it's derived from ?14:41
wpwrakit's all just dividers14:41
DocScrutinizerbecause there are lots of dividers and switches and latches and whatnot in between14:41
DocScrutinizerall of those not properly shielded in-chip, as jitter free never been a design parameter for that clock14:42
wpwrakhmm, i would naively assume that a divider by itself is fairly jitter-free14:43
DocScrutinizerand a devider isn'r per se jitter free14:44
wpwrakshielding, i don't know, of course14:44
wpwrakbut then, considering that beading the clock didn't make any difference, it seems that it's not overly dirty14:44
DocScrutinizernope, a divider may count up to a limit, then reset. The reset for sure may have diferent properties with signal delay than the normal increment. Just as one simple example of imanent jitter14:45
DocScrutinizerthen there's also crosstalk jitter14:45
wpwrak(reset) sure, but the output is always the reset, never the increment14:46
wpwrak(well, never the increment-sans-reset)14:46
DocScrutinizerthe output might even be latched by a completely unrelated clock14:46
DocScrutinizerhonestly, you can't assume any quality regarding jitter whatsoever, from a storage or similar clock14:47
wpwrakbig maybe. usually the whole clock tree is derived from the same source. of course, there may be fun effects if different paths merge14:47
DocScrutinizerit's digital domain, while your TX clock basically is analog domain14:47
wpwrakwell .. i'll try my luck with the rc bandpass. if it works, praise to ingenic's diligent engineers :) if not, all hail our crystalline savior ;-)14:48
DocScrutinizerrequirements for digital are just-in-time, and correct sequence aka propagation delay. Requirements for analog are amplitude and signal waveform stability, jitter free, and low freq error14:50
wpwrakwell, it's a digital output. so if the signal driving it isn't too crazy, it would have a clean waveform. this is a simple chip, so i wouldn't expect a lot of fancy detours that could introduce problems. but let's see ...14:58
wpwraksimulation says, in a configuration like this: http://www.play-hookey.com/ac_theory/band_pass_filters.html15:11
wpwrak100 pF, 68 Ohm, 150 Ohm, 100 pF, from left to right, should yield reasonable results15:12
wpwrakdo these values sound appropriate or should i aim for entirely different values ? (still need to do the analytical verification)15:13
DocScrutinizerthat's even starting at such simple things like chip internal VDD, which is the digital VDD for this output, incl all the internally generated noise on it. For a proper external clock generator you'd include a choke and a buffer C to decouple the clock VDD from rest of circuit, as on a clock with high requirements on jitter etc you don't tolerated the typical digital amplitude variations (high: 0.7..1.0 * VDD; low: GND - 0.7V .. 0.3 *15:14
DocScrutinizer(R, C) hmm, sounds reasonable. Just make sure your input and output impedances are way below (in) rsp above (out) those values15:16
wpwrakout, no problem. for input, i actually tried to be reasonably close to what i expect the driver's impedance. but lemme check if anything is specified ...15:17
DocScrutinizeror, alternatively, include any known impedance into your calculation15:17
wpwrakssd clock is specified at 4 mA .. that's ...15:18
wpwrakIoh = 10.2 mA (typ), Voh = 2.4 V, i.e., a 900 mV drop, so Ron = 88.2 Ohm. hmm.15:21
wpwrakyou said way below. let's make my resistor a bit larger then ...15:22
wpwrakthere, 47 pF and 220 Ohm15:23
wpwraktrick question: what do you have to do when the "continuous wave" looks like this: http://downloads.qi-hardware.com/people/werner/tmp/ghost.png ?15:29
wpwrakanswer: power-cycle the USRP ;-)15:29
wpwrakit likes to play these little games. not sure what's happening. at least now i know that i should always reset it before starting any measurements. before figuring out that part, i had been chasing some 20 dB mystery differences for days ...15:31
DocScrutinizercalculate your highpass so it will work with and without a R of (here) 88.2R in series to C115:31
wpwrakyeah, looks good. peak shifts a little bit to lower frequencies, but not excessively. maybe 1-2 MHz.15:36
wpwraknaw, more. 3-4 MHz. hard to read those logarithmic diagrams :)15:36
wpwrakanyway, it's flat up there. so not a big change. and the rest stays pretty much the same.15:36
DocScrutinizertime for 1264843015:39
wpwraknice :)15:40
wpwrakhere, it's time for laundry-in and trash-out. then a bit of food, rework, and then we'll see whether it's champagne or a bottle of cheap booze :)15:41
steve|mI'd rather stick with some 4887915:42
wpwraksteve|m: GOOD choice ! ;-)15:47
wpwrakplus 720942 :)15:49
DocScrutinizer48879, hmm yummy15:50
steve|mI once picked vid/pid 0xB00D 0xC0DE for an usb bootloader ;)15:53
steve|mbut 0xBOO7 0xL04D is nice, too :)15:54
qbjectHi all.15:59
qbjectHas anyone here used Atanua or similar logic simulator software?16:03
Action: wpwrak thanks steve|m for the idea :)16:12
qbjectwpwrak: do you know of a FOSS way for me to put virtual logic circuits together and test them without learning verilog?16:29
wolfspraulqbject: you may want to look through the (free) tools assembled in the fedora electronic lab16:31
wolfspraultoped, magic, alliance, gtkwave, etc.16:31
wolfspraulyeah, sure. report your experience back here :-)16:33
wolfspraulI know pretty much nothing about these tools either, except that they exist.16:33
wolfspraulI have some more work to do in KiCad/boom/brdhist/QCad16:35
wolfspraulget to IC stuff later...16:35
qbjectWill do. Might be a while before I become competent to assess, as I'm simultaneously reading up on CPU design and FORTH16:35
wpwrakDocScrutinizer: sigh. last entry of http://downloads.qi-hardware.com/people/werner/wpan/rework-20110113/16:37
wpwrakqbject: (logic circuits) i don't know much about these. i use qucs fairly extensively to simulate analog circuits, though. it should also be able to do digital.16:38
qbjectwolfspraul: are you not sleeping any more?16:38
wolfspraulI'm in Germany right now, returning to China in a few days though.16:40
qbjectwpwrak: Also sweet. As long as it can do the usual gates, I'll be good.16:40
qbjectwolfspraul: Ahh, cool. Good trip?16:40
wolfspraulqbject: to Germany? yes sure. Good 27c3 conference, good new contacts in Berlin.16:44
wpwrakDocScrutinizer: either your jitter theory has indeed some merit or the time-space continuum simply refuses to be bent more than 30 dB out of shape around the ben16:45
wpwraknext stop: crystal. the moment of truth.16:46
wpwrakDocScrutinizer: in any case, thanks a lot for your help ! it's also reassuring to know that i didn't miss anything obvious elsewhere.16:49
qbjectwolfspraul: sounds like an amazing get-together.16:57
rohola werner18:25
rohwpwrak: what are you trying to do? (bend time?)18:25
wpwrakroh: heh ;-)18:34
wpwrakroh: naw, the idea is to get the wpan stuff to work on the ben reusing the ben's clock (and crystal)18:34
wpwrakroh: unfortunately, i found out that there's a fair bit of noise and that noise seems to come from the clock.18:34
wpwrakroh: alas, i can't tell with certainty, also due to equipment limitations. the next iteration should bring more clarity. if a board with a crystal has the same noise pattern, then the noise comes from somewhere else. if not, then we have the culprit.18:37
wpwrakroh: at the same time, the USB-based board looks good. i haven't done any BER testing yet, but the spectrum and rssi patterns all look healthy.18:38
rohdont overoptimize ;)18:38
wpwrakroh: BER is probably also the only thing that's easy to check for production testing.18:38
rohmeaning.. is using another crystal that bad for you?18:39
wpwrakroh: ah, i don't like crystals. also, the crystal makes the thing bigger.18:39
wpwrakroh: the price difference is negligible for the small quantities we're looking at at the moment. but still, it's nice to make the best of it.18:40
rohhehe.. as long as the part exists its good and easy18:41
rohi failed at buying black screws18:41
rohnow ive ordered the ST2.2 metal screws in 'blank, zinc' since i can only buy sizes ST2.9 from upwards in black18:42
wpwrakyou can always paint them :)18:42
wpwraka can of epoxy paint goes a long way :)18:43
rohnaah. that scratches of and sticks into the small places where you would like to apply the screwdriver ;)18:43
rohthe only proper way to color screws seems to be galvanisation18:44
wpwrak(small places) i think the screwdriver will just win :)18:44
wpwrakbut yes, the stuff comes off18:44
wolfspraulroh: you there?18:48
wolfsprauljust a heads up, you know I ordered 10 violet cases from you, so that's moving...18:49
wolfspraulbut I wanted to let you know I am thinking about rc3, and my current plan is maybe 80 units18:49
wpwrakroh: all sleep has been cancelled until easter :)18:49
wolfspraulso that would mean another 80 violet cases. but that's later. don't order now, I will ponder some more.18:49
wolfspraulno no, just way in advance. just so you've heard that number already. 80.18:50
wolfspraulit will be between 50 and 100, I am leaning towards 80 now.18:50
wolfsprauland I want cases for all of them, and only offer fully assembled units.18:50
wolfspraulfor cheap things like screws and such you can already source 100 sets, if that even makes any significant price difference.18:51
wolfspraulbut for the more expensive stuff, don't source yet, I will only order those 80 in a month or so, if all goes well.18:51
wolfspraullet's do the next 10 first :-)18:52
kristianpaulwow 80 !18:57
wolfspraulkristianpaul: ah yeah, better don't ask. hardware is painful.19:00
wolfspraulonce you start, you just have to continue and slowly increase the volume.19:00
kristianpaulthat applied to then Ben Nanonote as well?19:00
wolfspraulI have no choice but to pull forward, make a complete product out of it (case, accessories, certification, box, manual, etc).19:01
wolfsprauloh sure, even more so19:01
wolfsprauland unless I have 50 or so in stock, it makes no sense to do a launch19:01
wolfspraulotherwise the launch press release goes out, some media pick it up, but I cannot deliver19:01
wpwrakeven 50 isn't a lot :)19:01
wolfspraulof course if nobody picks it up, and I have no marketing power to sell them, I get stuck with all the junk19:02
wpwrakbetter delete that from the logs ;-)19:02
kristianpauldid you made a launh for the ben nanonote?19:02
wolfspraulif I sell for 499 USD finding 50 actual paying customers is a nice achievement19:02
wolfspraulI'm not deleting any of this from the logs.19:02
wpwrak(just kidding)19:02
wolfspraulI'm just saying I cannot make a launch if I have 10 in stock.19:03
wolfspraulit all makes no sense, then I am wasting my time, and the chance to say 'new product launched', and cannot deliver.19:03
wolfspraulit's all risky19:03
kristianpaulI remenber in 2009 i read the first blog post about it, but then the first 1000 units, did i miss the launch?19:03
Action: Jay7 should consider about selling Milkymist here :)19:03
wolfspraulJay7: a potential distributor? YAY!19:03
Jay7but I don't know our custom laws :(19:03
wolfspraulah, that was Russia, right?19:03
kristianpaulJay7: call then ! :-)19:03
Jay7our laws are totally crazy..19:04
Jay7wolfspraul: yeah19:04
wpwrakmm1 is tricky because there's no way of telling what will stick. and of course, the amount of money available for gambling is limited.19:04
wolfspraulwell I read about the great new Russian open source plan19:04
Jay7I'll ask some people19:04
wolfspraulso you can email Vladimir directly ask for import permission :-)19:04
Jay7wolfspraul: they just heating the air19:04
Jay7no real move19:04
Jay7it's ok here19:05
wpwrakJay7: what's the problem with customs actually ? are they just difficult or is it all a question of bribes ?19:05
wolfspraulJay7: if you are serious about this idea, you should get one m1 asap, to learn about the product, show it to potential customers, etc.19:05
wolfspraulI still have 5 from the rc2 run right now, and I am holding them back a little for people who are really serious about the future, distributors, contributors, etc.19:05
Jay7wpwrak: I know nothing about need to certify this device to sell here19:05
wolfspraulso I would very much like to sell you one :-)19:05
Jay7and nothing about custom fee for resellers19:06
wpwrakJay7: so it's not just customs. i see.19:06
kristianpaulJay7: there is ebay in russia?19:06
wolfspraulI don't think certification is a problem, even now we already know we meet the CE and FCC criteria.19:06
wolfspraulto Russia, we would need to be careful about the power adapter19:06
wolfspraulit's always the same, we just have to start and learn19:06
Jay7wolfspraul: russia is using euro power plugs19:07
Jay7so shouldn't be a problem :)19:07
wolfspraulJay7: email me, then we find a way to pay and ship to you.19:07
wpwrakwolfspraul: (power) also argentina, at least if doing it "above the table"19:07
Jay7wolfspraul: I'll consider lawyer before :)19:07
wolfspraulyou should get a full unit including case, I don't have all parts in one place right now but we will find a way to pull it off.19:07
Jay7wait till next week19:08
wolfspraulsure, up to you19:08
wolfspraulthe thing is - Russia has a strong open source scene19:08
Action: kristianpaul wants his case 19:08
wolfspraulif we do a launch, and you have some stock at the launch day, that would be cool19:08
Jay7I'm interested in distributing some 'special' hardware here19:08
wolfspraulbut of course there is a lot of risk in that, not sure you want to take that risk...19:08
Jay7e.g. sheevaplugs, some arm boards, etc :)19:08
Jay7I like this HW :)19:09
wolfspraulI'm taking enough risks already, I cannot take more. So you can only buy things from me. I cannot send you x units in advance, you pay later etc.19:09
wolfspraulbut I do know that if we had a distributor in Russia _in advance_, there would be some business (=sales)19:09
wolfspraulbut that distributor has to have local stock, and be able to ship within russia in a controlled way19:10
Jay7wolfspraul: pre-paid should be ok :)19:10
wpwrakkristianpaul: ah, did you get your toys today ?19:10
kristianpaulwpwrak: http://oz9aec.net/index.php/gnu-radio/gnu-radio-blog/411-quisk-a-software-defined-radio-for-linux19:11
Jay7people here may pay forward and wait for delivery19:11
kristianpaulwpwrak: not :-(19:11
wpwrakkristianpaul: blargh. what went wrong ?19:11
kristianpaulI was able to reach the fedex office in cali, now is coming to buga, hopefully tomorrow (they argue)19:12
wpwrakkristianpaul: hmm, good luck on a saturday ...19:13
kristianpaulthats un fair buga is just one hour far from cali, ant they suposelly have up to 48 hrs to deliver !!19:13
kristianpaulyeah hopefully tomorrow :-)19:13
wpwrakkristianpaul: oh, here it takes them something like an 8 hours period as well. sometimes early, sometimes late. needless to say, they're less than 1/2 hour driving distance from my home.19:14
wpwrak(well, driving time. including all delays and traffic jams they could possibly encounter on the way. that is, except rush hour, when everything just stops for an hour :)19:15
kristianpaulno excuse here our highways are the best of the country19:15
kristianpaulis fault of that fedex method of use a thirdparty for places in wich they dont want put office.19:16
wpwrakprobably too dangerous ;-)19:17
kristianpauli'm a bit afraid, lest hope not19:17
Jay7hm.. quick googling show that our customs fee for commercial use is about 40%19:28
Jay7looks insane..19:28
wolfspraulJay7: depends on what we get them to accept as value19:33
wolfspraulthere are many options, but the only way to make progress is to start trying what works.19:33
wolfspraulfor example we can sell 'kits' to you, then we declare a much lower value like 100 USD or so, per kit.19:33
wolfspraulwhich also depends on whether you can work with 2 invoices, or you need 1. etc. etc.19:33
wolfspraulthe normal stuff :-)19:33
wolfspraulthe other day I read an article about a whole division at Mercedes whose job it is to disassemble fully built cards, ship them as parts, and then reassemble them in the destination country.19:34
wolfspraulthey have hundreds of people doing this all the time! crazy world...19:34
wolfspraulit does create jobs though, I mean one could disassemble and reassemble the car a few more times, to create even more jobs?19:35
Jay7hehe.. this way was widely used on our east when transferring auto's from Japan :)19:35
wolfspraullet me summarize my key thougts on Russia19:35
wolfspraulwe have sold 5-10 nanos there, all one by one with fedex or ems19:35
wolfspraulall arrived, we had no customs problems19:36
Jay7btw, it should be possible to make cases here19:36
wolfspraulI know that we could have sold a lot more if there would be a local distributor.19:36
Jay7so, only boards should be shipped19:36
kristianpaulwow HSL 2.75G Femtocell is WIP support in openbsc !!19:36
wolfspraulfor m1, it's going to be the same.19:36
Jay7wolfspraul: I have one NN shipped by CELF, please add to your numbers ;)19:37
kristianpauli hope this is cheaper than the other BTS they use.19:37
wolfspraulJay7: I will probably move to selling whole products asap.19:37
wolfspraulthe reason is that there are many parts, also accessories, shipping or retail box, etc. it becomes very complicated if I sell some parts here, some parts there.19:37
Jay7but from customer side it will be easier (and cheaper) to do direct order from you19:37
wolfspraulso I will make one big thing out of this.19:37
wolfspraulwith the case, you can try. -but- it's a lot of work, many details. I am buying cases from roh and I would be crazy to try this myself.19:38
wolfspraulJay7: what will be easier/cheaper? don't understand19:38
wolfspraulas passionate as I am about copylefting everything, documenting the process, the sources, costs, etc., I still have huge respect for manufacturing work.19:39
wolfspraulso it's not like "oh, this is open, so I do it myself".19:39
wolfspraulfor me it's "this is open, I can let someone else do it" :-)19:39
Jay7wolfspraul: I mean buyer19:39
Jay7i.e. someone who will buy e.g. Milkymist19:40
wolfspraulyou mean someone in Russia?19:40
wolfspraulwell, two things19:40
Jay7it's cheaper to order directly via internet19:40
wolfspraulfirst of all, if a Russian customer knows he is being served by a Russian company, that removes a whole big chunk of uncertainty around shipping delays, customs, maybe also payment options19:41
Jay7because of on custom fee for personal delivery :)19:41
wolfspraulwe can declare a larger shipment with big discounts19:41
wolfspraulthere are many options19:41
wolfspraulit took me a while to understand that in business (yeah well), there is nothing wrong if the 'customs invoice' 'commercial invoice' 'shipping invoice' 'insurance invoice' all have totally different values.19:42
wolfspraulbut what I wanted to say about distributors, when I have a distributor somewhere, I stop selling direct to that country or countries.19:42
wolfspraulinstead I redirect all sales/requests to the distributor19:42
Jay7well.. I'll talk with lawyer about this19:43
wolfspraulof course this must be within reason, i.e. if the distributor is lazy and marks up the price by 200%, and all customers complain, then I will stop working with that distributor and ship direct.19:43
Jay7may be things are simple19:43
wolfspraulbut that has never happened so far.19:43
wolfspraulin Russia a distributor would make a lot of sense, because19:43
wolfspraula) there is a big and strong open source scene19:44
wolfspraulb) there are serious difficulties in shipping and customs that a Russian distributor with local stock could overcome19:44
wolfspraulif you are interested, my proposal would be that you first buy 1, to learn about the product yourself.19:45
wolfspraulyou cannot sell somethign you don't know.19:45
wolfspraulif that looks good, and others are telling you they would like to buy this from you, you can order 5 or 10, then for that shipment we need to try to find a customs optimized way.19:45
wolfspraulbut first steps first, ask your lawyer etc.19:45
wolfspraulI would love to work with a distributor in Russia, you would have my full support.19:45
Jay7well.. we can try at least :)19:55
Action: Jay7 -> sleep20:00
qi-bot[commit] Bas Wijnen: lists and bugfixes http://qi-hw.com/p/iris/f4cac9b20:11
qi-bot[commit] Joachim Steiger:  added cc icons, added copying, added shielding sheet, lots of details http://qi-hw.com/p/m1/985061d20:46
qi-bot[commit] Joachim Steiger: really commit http://qi-hw.com/p/m1/febca8920:46
qi-bot[commit] Andres Calderon: kccomp.py has been fixed http://qi-hw.com/p/xue/61118e420:48
qi-bot[commit] Joachim Steiger:  v1.1 http://qi-hw.com/p/m1/d07923e23:50
qi-bot[commit] Joachim Steiger:  v1.2 http://qi-hw.com/p/m1/dabbae923:50
--- Sat Jan 15 201100:00

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