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| 04:58.59 | ZetaR | Looking at the rev U2b pdf ESD protection. I had a thought that the touchscreen connector may need TVSD, since you could get ESD coupled capacitively through the screen. There seems to be some support for this in manufacturer recommendations, e.g. http://www.ti.com/lit/an/sbaa036/sbaa036.pdf |
| 04:59.19 | ZetaR | Looking for a more comprehensive doc on the issue now. |
| 04:59.55 | ZetaR | (ESD) *See figure 9. |
| 05:07.39 | ZetaR | The TSC2007 does claim "enhanced" ESD protection. Not sure what is considered sufficient though. |
| 05:27.05 | ZetaR | Hm. Some docs say that the screen dielectric is good enough on resistive screens and this is more of a problem for capacitive screens. Others recommend external TVS diodes, but don't mention builtin protection. The figure I cited does not have built in ESD protection, however. |
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| 07:06.48 | ilon | DocScrutinizer05: I have a few questions.. how does it work with receipts for payments to the shop? I were thinking about doing a down payment on a device for my company, but then i would need an invoice / receipt on the payment. Is this possible? or would it be possible to pay the estimated final price up-front, and get refunded if the final price is lower? |
| 07:19.04 | x29a | ilon: can you use the "order confirmation" email as receipt? |
| 07:19.39 | x29a | i would be more afraid of the time that lays between order and receiving of goods |
| 07:34.34 | ilon | x29a: there's some things that are required to be included on the receipt by law, and i think its roughly the same in sweden (where i live) and germany where the Neo900 UG is based |
| 07:35.21 | ilon | x29a: and even if could use the order confirmation email in conjunction with the credit card slip etc, its not really "enough" from a book keeping point of view |
| 07:35.53 | x29a | i see |
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| 09:22.55 | jonwil | Looks like the Neo900 project made the front page of Slashdot |
| 09:23.19 | jonwil | Lots of negative posts though, people saying "Why would I buy one of these pieces of crap instead of a Samsung Galaxy with a nice modded rom on it?" |
| 09:23.33 | jonwil | People not understanding why the Neo900 exists and what it is and isn't supposed to be |
| 09:23.47 | jonwil | And to be fair none of those people are in the target audience for the Neo900 |
| 09:42.02 | x29a | i hope the servers dont get slashdotted :/ |
| 09:43.06 | x29a | jonwil: id be the same if "noahs arc" would make it to the front page of slashdot (lets assume we believe in this stuff) |
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| 09:49.27 | jonwil | Me, I think the Neo900 has the potential to be the greatest phone ever made. |
| 09:55.32 | x29a | jonwil: yeah, the ideas are great, but whenever you are late to the market, the product itself does not make a difference to the sheep |
| 09:55.57 | jonwil | The fact is, most people dont want what the Neo900 has to offer |
| 09:56.12 | jonwil | They want a phone that is faster, thinner and runs all the privacy violating crap they use |
| 09:57.01 | x29a | yes, and what they see is the price, the "bulkyness" and therefor the reaction is understandable |
| 09:58.41 | jonwil | I used a Windows Phone of some sort the other day to search for something and compared to using my N900 and its physical keyboard, using the virtual keyboard crap on that thing was a pain. |
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| 10:49.08 | Kero | x29a: the shop already got /.ed :( |
| 10:51.36 | x29a | daqmn |
| 10:51.37 | x29a | damn |
| 10:51.47 | x29a | dos1: throw more bandwidth at the shop! |
| 10:51.58 | x29a | Kero: works for me |
| 10:54.15 | Kero | they did what they could (of course), check the irc logs if you want to know more. happened >24h ago, btw. |
| 10:54.49 | Wizzup | It doesn't matter if most people are not interested |
| 10:54.55 | Wizzup | as long as about ~500 people are interested |
| 10:54.59 | Wizzup | that is also the scope. |
| 10:58.46 | drathir | jonwil: wp in one sentence with n900 is a "crime"... ;/ |
| 10:59.09 | jonwil | xwrite-> |
| 10:59.24 | jonwil | In this context I was talking about how crap WP is :) |
| 10:59.25 | jonwil | so its ok :) |
| 11:00.10 | drathir | jonwil: ofc it was more from joke side... |
| 11:01.18 | drathir | but personally in my opinion no alternative to n900 ;/ exclude neo900... |
| 11:02.34 | drathir | jonwil: android is good plans mistake in practice... winscary is totally one big wth, almost not possible to use... |
| 11:03.24 | drathir | not yet saw tizen phone, but not think if them made any revolution... |
| 11:03.34 | jonwil | What surprises me is why Microsoft has persisted with the phone market when it hasn't had market share above single digit percentage in the entire life of Windows on phones (as far as I know anyway) |
| 11:04.39 | drathir | jonwil: /me avoid m$ as fire, when i can ofc.... |
| 11:05.48 | drathir | and personally tryin to switch as much as possible ppl to linux... |
| 11:06.16 | merlin1991 | just realised he totally forgot todo the order voucher thing |
| 11:07.28 | drathir | jonwil: even at mine n900 arch onboard... |
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| 14:04.39 | merlin1991 | DocScrutinizer05: who's the current neo900.org webmaster, still dos1? |
| 14:24.45 | DocScrutinizer05 | sure |
| 14:26.38 | merlin1991 | dos1 ping |
| 14:33.09 | DocScrutinizer05 | he's rarely online |
| 14:33.13 | merlin1991 | dang |
| 14:33.17 | DocScrutinizer05 | what's the problem |
| 14:33.32 | merlin1991 | well essentially my question is, if he still needs the static.neo900.org setup on my server |
| 14:33.39 | merlin1991 | the dns entry at least doesn't contain my server anymore |
| 14:34.00 | DocScrutinizer05 | yes, we removed that and I think we don't need it anymore |
| 14:34.25 | DocScrutinizer05 | it also conflicts with certs |
| 14:34.52 | merlin1991 | that is fixable ;) |
| 14:35.42 | merlin1991 | so if you don't need it anymore i'll remove the setup for it on my box, it's quite weird including lighttpd running a revers proxy in front of apache for proper etags :D |
| 14:36.11 | merlin1991 | so just get word from him and if it's not needed anymore i'll remove it |
| 14:36.56 | DocScrutinizer05 | I can positively tell we removed distributed static.n.o. from all the pages |
| 14:37.12 | merlin1991 | okay |
| 14:37.14 | DocScrutinizer05 | 2 days before we got slashdotted ;-P |
| 14:37.21 | merlin1991 | if you ever need it again, hit me up :) |
| 14:37.30 | DocScrutinizer05 | sure thing, thanks! |
| 14:38.44 | DocScrutinizer05 | we now have nginx for static content, dunno if it does a lot of goods for shop |
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| 14:45.24 | DocScrutinizer05 | ilon: the shop sends out invoice on payment. since the payment is a downpayment and no goods are sent, there's no tax listed in that invoice yet. For the final invoice when goods are sent this will look better |
| 14:45.57 | DocScrutinizer05 | ilon: yes, of course we refund when final price is lower, how can you ask? ;-) |
| 14:47.49 | DocScrutinizer05 | ilon: btw you got two active accounts now, on two different mail addr |
| 14:48.21 | DocScrutinizer05 | for the shop those are completely unrelated customer accounts |
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| 14:51.15 | DocScrutinizer05 | hehe, weekend /. time for users |
| 14:51.50 | DocScrutinizer05 | not as bad as it was on first impact |
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| 15:09.17 | ZetaR | DocScrutinizer05: Is it planned to add a GSM antenna switch like there is for the GPS? Use case would be to ensure modem uplink can be disabled securely when using GPS by itself. |
| 15:10.21 | DocScrutinizer05 | ZetaR: we monitor the uplink with smarter means, so it doesn't start to send when AT+CFUN=$off told modem to NOT do |
| 15:11.12 | ZetaR | Is that what LTC5508 and the two LMV221s are for? |
| 15:11.28 | DocScrutinizer05 | we don't trust in modem behaving, but we have it under tight monitoring and we got a global kill switch |
| 15:11.45 | DocScrutinizer05 | iirc that are the ones, yes |
| 15:12.43 | ZetaR | I see. I thought it might be hard to ensure that you can kill the link before it could broadcast its ID. |
| 15:13.21 | ZetaR | Why did you opt for active monitoring in this case and a passive solution in the GPS case? |
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| 15:35.01 | drathir | 3/w 31 |
| 15:35.17 | drathir | sry... |
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| 15:39.35 | merlin1991 | ZetaR: in my experience gsm atenna disable is not enough |
| 15:40.00 | merlin1991 | if your area has nice coverage even wrapping that shit without antenna in some metal it can still get through ... |
| 15:40.48 | ZetaR | merlin1991: Are you referring to designs that short the antenna to ground? |
| 15:41.33 | merlin1991 | hm I never tried that in connection to a battery operated device |
| 15:41.44 | merlin1991 | since yeah *ground* |
| 15:41.47 | ZetaR | That is what the neo900 is doing with GPS antenna. |
| 15:42.03 | ZetaR | Eh, I actually mean "common". |
| 15:42.05 | merlin1991 | gps needs quite a lot of antenna support |
| 15:42.21 | merlin1991 | my experinece is that even unscrewing a gps antenna disables a unit |
| 15:42.31 | ZetaR | (I don't actually like the term "ground" used to mean "common") |
| 15:42.38 | merlin1991 | but I had gsm data connection with gsm modules with just the chip under power ... |
| 15:43.40 | ZetaR | I guess that is probably because A: the transmitters are farther away (in orbit), and B: the GPS is reliant on receiving many signals at once with accurate timing. |
| 15:44.21 | merlin1991 | yes, so my main point is that disabling the antenna of gsm module might not be enough to keep it from transmitting stuff |
| 15:44.40 | merlin1991 | best solution cut its power ;) |
| 15:45.39 | DocScrutinizer05 | well, any switches in GSM antenna would be extremely expensive. And we trust the module so far that we accept a residual risk of it turning bad and trying to send and we need a 0.5s to take counter measures and yell the HUGE ALARM to user |
| 15:46.13 | ZetaR | Ah. I see. |
| 15:46.15 | merlin1991 | heh adpot the sw to preemtively cut gsm power as soon as it looks out of touch |
| 15:46.24 | DocScrutinizer05 | counter measure: simply cut power to module, this stops sending in no time |
| 15:46.47 | merlin1991 | and then 2 years of fine tuning the "is it acting okay" metric :D |
| 15:46.50 | DocScrutinizer05 | of course this also kills GPS |
| 15:47.02 | merlin1991 | combined module? |
| 15:47.05 | DocScrutinizer05 | yep |
| 15:47.31 | merlin1991 | from my experience stand alone gps modules are quite big, so that makes a lot of sense |
| 15:47.34 | ZetaR | Also, I guess GPS can be a security risk with only receiving (GSM transmission of location data?), but GSM requires transmission to be a risk. |
| 15:47.49 | Wizzup | how can gps be a security risk? |
| 15:48.10 | ZetaR | Wizzup: I guess increasing the accuracy of cell triangulation. |
| 15:48.29 | Wizzup | uh |
| 15:48.35 | DocScrutinizer05 | but our general policy is to "let the modem do what it wants" and just monitor closely so we learn we are under attack, rather than preventing all possible attack vectors - except that last one we possibly never heard about |
| 15:49.07 | DocScrutinizer05 | actually GPS is no security risk |
| 15:49.26 | ZetaR | Oh, what is the antenna switch for then? |
| 15:49.33 | Wizzup | ZetaR: gps is recv only |
| 15:49.35 | DocScrutinizer05 | so the GPS antenna blocker is for RMS / FSF only ;-) |
| 15:49.58 | DocScrutinizer05 | and for those who don't want to learn why GPS is harmless |
| 15:50.02 | ZetaR | Eh? Why are they concerned about the antenna switch? |
| 15:50.18 | Wizzup | holds up a sarcasm sign |
| 15:50.52 | ZetaR | Wizzup: I meant that a subverted modem could increase location accuracy by sending GSM information. Might be used in areas with poor cell coverage where GSM triangulation isn't feasable or accurate. |
| 15:51.04 | ZetaR | sending GPS information* |
| 15:51.19 | Wizzup | right, because gps is on the modem |
| 15:51.26 | DocScrutinizer05 | merlin1991: big and actually poor performance compared to a integrated AGPS in modem. The integrated AGPS takes advantage of cellular to get very fast TTFF |
| 15:51.46 | DocScrutinizer05 | and expensive |
| 15:52.18 | ZetaR | Yes. Though IMO this isn't much of an additional threat. It requires an active attack on the modem, whereas triangulation can be done passively and pervasively. |
| 15:53.17 | DocScrutinizer05 | anyway RMS/FSF never heard of trilateration so their rules say "any GPS chip must be separate from modem" - we made sure we can tell "there's no working GPS inside modem when you don't want any in there" |
| 15:53.28 | ZetaR | Unless you are using a directional antenna for your cell uplink (while wearing copious amounts of tin-foil). |
| 15:53.51 | DocScrutinizer05 | ~u-tdoa |
| 15:53.52 | infobot | hmm... u-tdoa is http://en.wikipedia.org/wiki/U-TDOA |
| 15:54.03 | DocScrutinizer05 | ^^ trilateration |
| 15:54.27 | DocScrutinizer05 | works in no time, with *any* arbitrary transmitter |
| 15:55.12 | DocScrutinizer05 | unless you use an *extremely* selective directional antenna |
| 15:56.12 | DocScrutinizer05 | "extremely selective" here means a -50dB with 10° off main axis, any direction and amount of "off main axis" |
| 15:56.27 | DocScrutinizer05 | so basically forget about that |
| 15:56.37 | DocScrutinizer05 | can't be done usually |
| 15:56.48 | ZetaR | So, e.g. using a parabolic dish antenna wouldn't fool it? |
| 15:56.57 | DocScrutinizer05 | prolly not |
| 15:57.10 | ZetaR | That is pretty sensitive. |
| 15:57.30 | DocScrutinizer05 | depending on antenna element in dish, a dish has a very poor far-off-damping |
| 15:58.09 | ZetaR | Not knowing that much about antennas I would probably try a helical element. |
| 15:58.24 | DocScrutinizer05 | that might work way better, yes |
| 15:58.53 | DocScrutinizer05 | but still magnitudes too poor for this U-TDOA defender to actually work |
| 15:59.25 | ZetaR | I see. And it would require a large apperatus as well as manual aiming to place a phone call. |
| 15:59.36 | DocScrutinizer05 | yes |
| 16:00.49 | ZetaR | Though, there are probably areas with poor U-TDOA coverage where it would work better, but that is an exceptional case. |
| 16:02.28 | DocScrutinizer05 | and mere guesswork |
| 16:03.26 | DocScrutinizer05 | afaik the NSA runs a U-TDOA broadband network in several areas of the planet, to detect and locate any transmitters between 100MHz and 6GHz |
| 16:03.57 | ZetaR | When I have thought about tracking countermeasures, the only thing I could think of that would be reliable would disabling the modem. And since the NSA pays close attention to when phones are turned off, you would have to schedule modem disabling to occur periodically when you would typically be away from home/work. |
| 16:04.25 | ZetaR | So that you can't actually tell when you are away from your usual call area. |
| 16:04.39 | DocScrutinizer05 | we did some calculations a several months ago. Some 50 stations in Germany would cover the whole thing, and each would need like 100 2TB harddisks to record the last 24h or somesuch |
| 16:04.58 | ZetaR | Whole thing? Whole earth? |
| 16:05.19 | ZetaR | Doh, stupid. |
| 16:05.22 | DocScrutinizer05 | prolly not |
| 16:05.25 | ZetaR | Whole Germany. |
| 16:05.32 | DocScrutinizer05 | yeah, mor elike it |
| 16:05.47 | ZetaR | (sorry if I say really stupid things sometime) |
| 16:05.51 | DocScrutinizer05 | one station is "cheap", prolly less than a million |
| 16:06.23 | ZetaR | And if you are talking about the USA, it has bases all over the world. |
| 16:07.20 | ZetaR | NSA could probably cover most of the world if they had access to deploy on those bases. Of course they could just use satellites too. |
| 16:08.33 | ZetaR | At least in Germany you arent part of the Five Eyes. |
| 16:08.45 | DocScrutinizer05 | yes, sattelites are already used for that, but they are a tad cumbersome to use in this scenario, once for the needed antennas and distance, and then also for the amount of data to store and possibly transmit |
| 16:09.38 | ZetaR | I see. Probably mainly used for "unusual" or "interesting" as well as military and foreign government transmissions. |
| 16:11.33 | DocScrutinizer05 | yes |
| 16:35.02 | ilon | DocScrutinizer05: Cool, assumed you would send out an invoice / receipt on down payment, just wanted to make sure before i started sending my companys monies. |
| 16:35.37 | ilon | DocScrutinizer05: and regarding refund, thats on the same tab, need to make sure before i get something for the company |
| 16:36.23 | DocScrutinizer05 | sure thing. Many thanks! |
| 16:36.36 | ilon | DocScrutinizer05: and finally, yes, i know i now have two different accounts, one for me, one for the company.. I'm still not certain on how i should do it.. I'm tempted to order a full neo900 for the company, and a spare board on my private account. |
| 16:36.51 | DocScrutinizer05 | if the invoice doesn't meet your needs, please holler. We can fix any problems regarding that |
| 16:37.02 | ilon | DocScrutinizer05: cool, thanks mate :) |
| 16:37.44 | DocScrutinizer05 | yw |
| 16:37.47 | DocScrutinizer05 | afk, bbl |
| 16:37.53 | ilon | DocScrutinizer05: one thought i got yesterday.. wouldnt the custom / tax when sending outside of EU be completly different for board only and full phone? |
| 16:38.12 | DocScrutinizer05 | I dunno |
| 16:38.26 | DocScrutinizer05 | prolly no tax at all on our side |
| 16:38.53 | DocScrutinizer05 | on your side though, customs will charge import tax |
| 16:39.04 | DocScrutinizer05 | we don't know about the amount |
| 16:39.30 | DocScrutinizer05 | in a hurry, be back later |
| 16:39.34 | DocScrutinizer05 | o/ |
| 16:39.37 | ilon | DocScrutinizer05: I'm in the EU, so for my account its a no-brainer |
| 16:39.49 | ilon | DocScrutinizer05: i where just thinking about the folks on the other side of the pond |
| 16:40.17 | ilon | that it might be a lot cheaper for them to get board and phone separately (higher duty charges on phones afaik) |
| 16:40.23 | ilon | DocScrutinizer05: laters |
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| 18:11.52 | ZetaR | I see that there is a lot of reliance on I2C for low-speed communication. If the asymptotic rise becomes a problem then the performance of these busses could be improved by using constant-current sources to supplement the internal pull-up resistors. See active pull-up https://web.archive.org/web/20140924144659/http://www.esacademy.com/en/library/technical-articles-and-documents/miscellaneous/i2c-bus/frequently-asked-questions/i2c-faq |
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| 18:12.21 | ZetaR | Active pull up changes asymptotic RC rise to a linear rise. |
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| 18:25.45 | DocScrutinizer05 | ZetaR: thanks! :-) |
| 18:29.48 | ZetaR | DocScrutinizer05: Sure. This is usually only needed for larger networks or higher speeds though. Series resistors at branches are also used sometimes for better balancing between receivers as well as to provide some overcurrent protection. |
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| 18:32.50 | DocScrutinizer05 | we have some FET level shifters for hackerbus and for one of the sensors iirc |
| 18:32.52 | ZetaR | Also, if the open drain current is equal with and without the current source (i.e. Ires-old = Iconst + Ires-new) then your power usage will be aproximately the same at the same frequency (slightly higher while transmitting if you are reusing internal pull-ups). |
| 18:33.49 | ZetaR | That's good. I would hate to fry part of the board because I made a mistake with that. |
| 18:33.50 | DocScrutinizer05 | yep |
| 18:33.59 | DocScrutinizer05 | :-) |
| 18:34.22 | ZetaR | Are you going to have TVSDs on the hackerbus? I saw that it was marked unfinished. |
| 18:34.32 | DocScrutinizer05 | HB should be 'safe' up to 12V or somesuch |
| 18:34.47 | DocScrutinizer05 | yes, there are TVS |
| 18:35.25 | ZetaR | Nice. I like a good margin of error like that, in case of momentary stupidity. |
| 18:35.36 | DocScrutinizer05 | too |
| 18:36.42 | ZetaR | Isolation would be a nice thing to have, but probably too space inefficient in a phone. |
| 18:38.09 | DocScrutinizer05 | isolation on a bidir thing like I2C is pretty hard to accomplish |
| 18:38.41 | ZetaR | There is an example circuit for iso on that page I linked to. |
| 18:38.54 | DocScrutinizer05 | sure, I didn't say impossible |
| 18:39.07 | DocScrutinizer05 | just takes quite a lot of components |
| 18:39.48 | DocScrutinizer05 | and a smart logic to decide on direction |
| 18:40.08 | ZetaR | Actually, I think you could do it with a lot less than they use there by using an SR-latch to change between directional and bidirectional. |
| 18:40.20 | ZetaR | Then use a directional opto-iso. |
| 18:40.29 | DocScrutinizer05 | btw >>Wayback Machine doesn't have that page archived.<< |
| 18:41.10 | ZetaR | Maybe pasting it broke it: https://web.archive.org/web/20140216232015/http://www.esacademy.com/en/library/technical-articles-and-documents/miscellaneous/i2c-bus/general-introduction/i2c-bus-protocol.html |
| 18:41.29 | DocScrutinizer05 | that works better |
| 18:42.36 | DocScrutinizer05 | but it's pretty terse |
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| 18:43.52 | DocScrutinizer05 | whatever, I'm aware what's needed for isolation, we probably won't do it. For the usecase, proper OVP and level shifters are fine |
| 18:44.51 | DocScrutinizer05 | please see hackerbus whitepaper |
| 18:45.28 | DocScrutinizer05 | "Resources" -> http://neo900.org/stuff/papers/hb.pdf |
| 18:46.33 | DocScrutinizer05 | btw we got level shifters only on I2C |
| 18:47.27 | DocScrutinizer05 | we wouldn't want to restrict possible usecases too much for the other signals. So they only get some series R and OVP |
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| 19:01.38 | DocScrutinizer05 | oops, nevermind, we got level shifters on all GPIO |
| 19:03.01 | *** part/#neo900 panais (~pan@62-81-47.netrun.cytanet.com.cy) |
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| 19:10.52 | DocScrutinizer05 | ZetaR: anyway I appreciate a lot that finally somebody at least has a _look_ at our schematics :-) Many thanks! |
| 19:14.21 | DocScrutinizer05 | ZetaR: you might want to have a look at our NFC whitepaper too ;-) |
| 19:14.58 | DocScrutinizer05 | http://neo900.org/resources page is MASSIVELY underrated. It's basically our best page |
| 19:18.05 | Humpelstilzchen | too technical |
| 19:30.43 | ZetaR | Back. Got a phone call. |
| 19:33.12 | ZetaR | DocScrutinizer05: How many components would you consider too many for one signal line? I could try designing an iso circuit using very few components. I do agree that the shifters are probably fine but I have this concern: This is the sort of phone I would want to last for 10+ years, and one of the top causes of failure of a well cared for phone is going to be things coming in from the external lines. |
| 19:34.11 | ZetaR | Also, not everyone would have the expertise to correctly evaluate things they might want to plug into the hackerbus. |
| 19:34.50 | DocScrutinizer05 | ZetaR: isolation will need opto coupkers which need to be active all the time. So this adds on power consumption. |
| 19:35.44 | ZetaR | DocScrutinizer05: Not necessarily. You could wire it so that it only uses power when the bus is not at its idle voltage level. |
| 19:35.47 | DocScrutinizer05 | the hackerbus should be absolutely safe for up to 12V overvoltage and the usual high level of ESD protection needed on all external connectors |
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| 19:36.25 | DocScrutinizer05 | ZetaR: the bus is always active, for some of them signals. Particularly I2C |
| 19:36.30 | ZetaR | Yeah, you have a good point. |
| 19:37.17 | DocScrutinizer05 | when you want isolation, simply add it ;-) |
| 19:37.25 | ZetaR | Hmm, you could have a GPIO to activate the connection. |
| 19:38.52 | ZetaR | I guess I am just brainstorming about things that could happen, but most if it would be due to not being careful enough with the design of the external board. |
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| 19:41.25 | DocScrutinizer05 | isolation won't help you a lot, it would as well let escape the blue magic smoke when you apply massive overvoltage. It's pretty much irrelevant if you have to swap-replace a FET level shifter or a logic chip in iso-circuit |
| 19:41.27 | ZetaR | Oh. I had a question about the TVS: Is there a reason why bidirectional TVSDs are always used on busses where Vbus > common when it is operating correctly? AFAIK they are just specialized zeners put back-to-back, so you get breakdown in one direction and forward-drop in the other, so if you just reverse biased them you would get rid of the forward-drop and turn-on. |
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| 19:42.42 | DocScrutinizer05 | I think it's a bad habit |
| 19:43.16 | ZetaR | Which is? To use bidirectional? The Neo900 does it. Is it just because that is what is availible? |
| 19:43.16 | DocScrutinizer05 | we tried to find unidir true Zener TVS that work as clamp diode for reverse voltage |
| 19:43.59 | DocScrutinizer05 | and I think we used them where they were applicable |
| 19:44.38 | ZetaR | All the TVSDs I see on the schematic PDF are bidirectional. |
| 19:44.46 | ZetaR | Or at least the symbols are. |
| 19:44.55 | DocScrutinizer05 | the symbols are odd, yeah |
| 19:45.02 | DocScrutinizer05 | not my symbols ;-) |
| 19:45.30 | ZetaR | The Zener is a lie! =) |
| 19:45.43 | DocScrutinizer05 | it's one of the 45 todo points between me and GDC |
| 19:48.42 | ZetaR | Wait. These are varistors, not zeners. |
| 19:49.37 | DocScrutinizer05 | aaah yes, we got those too, and I'm still not sure what's the actual component Nikolaus planned for it and if it's ACKed yet or not |
| 19:50.22 | DocScrutinizer05 | picking the right TVS is an art rather than a science ;-) any suggestions for particular part numbers welcome |
| 19:50.59 | DocScrutinizer05 | wpwrak and me had a few days of fun with that already |
| 19:51.06 | ZetaR | V5.5MLA0603N = 3.5V working voltage, 13V clamp @1A varistor |
| 19:51.20 | DocScrutinizer05 | sounds... good |
| 19:51.34 | ZetaR | Hmmm. I don't really have experience with miniaturized design. |
| 19:51.40 | DocScrutinizer05 | except for varistors usually *aging* |
| 19:52.29 | ZetaR | Varistors IIRC: larger current capacity, several orders of magnitude slower, degredation with repeated transitions between conducting and nonconducting. |
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| 19:53.29 | ZetaR | When studying surge protection my thought was "this is what you would have in a disposable surge protection device that you stick on a cable". |
| 19:53.45 | ZetaR | Mainly because of the degredation. |
| 19:54.01 | ZetaR | They also typically fail shorted. |
| 19:54.30 | DocScrutinizer05 | hmmm "repetitive pulse capacity" up to 10000 is promising on that one |
| 19:55.24 | DocScrutinizer05 | yep, they have increasing leakage current with number of events |
| 19:55.36 | DocScrutinizer05 | that's why I don't like them much |
| 19:56.29 | ZetaR | That data clashes with what I have read about varistors. |
| 19:57.07 | ZetaR | Which is that they have a large degradation problem with repeated transisions. |
| 19:58.16 | *** part/#neo900 tester1 (4e636222@gateway/web/freenode/ip.78.99.98.34) |
| 20:00.58 | ZetaR | I don't see any response time data. |
| 20:02.18 | DocScrutinizer05 | sorry? that's exactly what I told |
| 20:02.27 | DocScrutinizer05 | [2015-05-23 Sat 21:55:23] <DocScrutinizer05> yep, they have increasing leakage current with number of events |
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| 20:07.07 | ZetaR | Oh, I was actually referring to the clamping voltage dropping. |
| 20:07.35 | DocScrutinizer05 | about expected degradation see littelfuse_mlv_mla.pdf page 5: >> ...multiple pulses at its peak current rating (150A, 8/20μs). At the end of the test,10,000 pulses later, the device voltage characteristics are still well within specification.<< |
| 20:08.03 | DocScrutinizer05 | spped is said to be 1ns |
| 20:08.11 | DocScrutinizer05 | speed* |
| 20:08.18 | ZetaR | Yeah. I saw that. I was saying that I had read that this is not typically the case for varistors. But I guess this was incorrect. |
| 20:08.49 | DocScrutinizer05 | alas a varistor is "symmetrical" which wouldn't help for clamping reverse voltage |
| 20:09.31 | DocScrutinizer05 | I think Littelfuse also agrees that this is generally not typical for varistors ;-) |
| 20:09.43 | DocScrutinizer05 | they say it's unique for their varistor |
| 20:09.50 | ZetaR | Ahh, I see. |
| 20:10.26 | ZetaR | That is pretty good then, for a varistor. |
| 20:12.18 | ZetaR | As far as TVSDs go, there seems to be a popular setup with the SOT-23-6: 4 signal lines with steering diodes to rail voltage, and a zener inbetween the voltage rails. |
| 20:12.47 | ZetaR | I can try looking for smaller packages (I usually filter out anything smaller for my projects). |
| 20:13.12 | DocScrutinizer05 | yes, we used exactly that in our err, USB? |
| 20:13.41 | ZetaR | Okay, so that is IP4220 |
| 20:13.54 | DocScrutinizer05 | wpwrak: do you remember what we picked for TVS on hackerbus? |
| 20:14.23 | ZetaR | Is there a reason why the VBus is N/C on the IP4220? |
| 20:18.13 | ilon | DocScrutinizer05: How's the sourcing of n900 looking right now? |
| 20:20.21 | DocScrutinizer05 | ilon: we got a ~85 preorders so far |
| 20:21.29 | ilon | DocScrutinizer05: reliable source? |
| 20:22.09 | DocScrutinizer05 | yes |
| 20:22.21 | DocScrutinizer05 | very reliable |
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| 20:22.36 | ilon | DocScrutinizer05: Oh right, the mozilla ones? |
| 20:23.07 | ilon | DocScrutinizer05: What number would you expect to source? any changes from last chat we had about it? |
| 20:24.21 | jonsger | ilon: mozilla ones? |
| 20:26.09 | ilon | old dev units if i recall correctly, not sure if they went the way of this project or not tho |
| 20:26.18 | DocScrutinizer05 | ilon: nope. Sourced in China refurbished. I hope for well, 400 |
| 20:26.31 | DocScrutinizer05 | they did |
| 20:26.51 | ilon | DocScrutinizer05: did you eventually get ANY of the batteries to work? |
| 20:26.53 | DocScrutinizer05 | but they are not canibalized for resale |
| 20:27.11 | DocScrutinizer05 | a few seem to be still ok |
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| 20:27.19 | ilon | mkay |
| 20:27.30 | DocScrutinizer05 | like 12 of 55 |
| 20:27.40 | ilon | :DD |
| 20:28.43 | ilon | seems there are still a few sellers out there |
| 20:44.58 | ilon | DocScrutinizer05: are you going to source batch of original batteries (separately) as well for the complete devices? Or would you rely on the refurbs having "good enough" batteries? |
| 20:49.04 | DocScrutinizer05 | I dunno if they have *any* batteries. We would source something that works |
| 20:49.46 | DocScrutinizer05 | sourcing batteries is more a problem of finding a good one, there's no shortage of BL-5J battery offers |
| 20:50.28 | DocScrutinizer05 | of course we will source sufficient batteries of tested qualities for all our customers |
| 20:50.53 | ilon | DocScrutinizer05: the refurbs I'm ordered so far have come with what seems to be genuine (but i doubt new) batteries, which have worked fairly well |
| 20:51.30 | DocScrutinizer05 | we'll see. Not anything giving me a lot of headache right now |
| 20:52.31 | DocScrutinizer05 | I'm just busy coordination a server migration with dos1 and our new co-sysop merlin1991 who kindly offered to help a bit every now and then |
| 20:53.45 | ilon | DocScrutinizer05: ah :) |
| 20:54.18 | ilon | DocScrutinizer05: I would probably be able to help a fair bit on that if you needed it |
| 20:54.58 | ilon | I will verry soon have way more resources (hardware and bandwidth) on my hand that i could resonably use :P |
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