#milkymist IRC log for Wednesday, 2012-03-21

cladamwgood morning !01:01
cladamwwpwrak, one quick question, why did you correspondingly find that TI "Input Capacitor" for explaining 150uF T520 polymer-tantalum capacitors cap ? Although 150uF those are for usb switcher's output use.01:09
cladamwAlthough TI strongly recommended polymer-tantalum in their both input and output of related product. :-)01:11
wpwrakcladamw: oh, i just remembered having seen that comment on non-polymer caps. not sure why they recommend such a large margin, though01:11
wpwrakcladamw: my "bible" (the circuit degsiner's companion) doesn't have anything nasty to say about tantalum. so i don't know what TI found :)01:12
wpwrakbut i thought i'd pass the warning on01:12
wpwrakthe implied message is of course that, should you some day consider a non-polymer tantalum cap for some reason, we may need to find out what those issues are01:13
cladamwsince we've not measured surge current & (ac)ripple vs, temperature curve relationship, some good news might be behind them.01:15
cladamwbut it'okay that we go for use of polymer-tantalum cap. :)01:16
wpwrakyeah :)01:16
cladamw(trace lengths) about this. I do really have no further ideas now although you seems are against.01:17
wpwrakhmm ?01:18
wpwrakyou're talking about the RAM ?01:18
cladamwyour last comments that mentioned "That doesn't sound excessively demanding, even without zig-zagging."01:18
cladamware you serious ? ;-)01:19
wpwrakwhat i meant: the layout people shouldn't find it too difficult to follow these design rules01:19
wpwrakmaybe the clock is more difficult, with only 0.5 mm of difference recommended01:19
cladamwoah...sure, yes if I tell them. :-)01:19
cladamwyes, but my concerns is that I don't have no idea on that to change current routes between fpga and RAM. ;-)01:20
wpwrakdo you think they'll be able to keep the existing routes ? we have quite a lot of changes ...01:21
cladamwnot about yes we knew the rules from chip Micron. so if you'd prefer to change it, i may not agree it.01:22
wpwrakso you say you wouldn't want to change the routing, even if it violates micron's design recommendations ?01:22
cladamwyes, I think house will change the "area" under fpga but not the routes existed area there between outside of fpga and RAM.01:22
cladamwwpwrak, yes, i am trying to say like that (i.e) I'd prefer to keep current rc3 routes.01:24
wpwrak(what they'll change) we'll see :) depends a bit on how crowded the layout is so far. e.g., i would expect that running DVI across the FPGA will upset a lot of things01:24
wpwraklet's do it like this: 1) if they have to reroute everything - including RAM - anyway, then they may as well do it properly (following the micron recommendations)01:25
cladamwoah..yes, it's already crowed there, house will inform me like that since the (changes/area) under fpga must be changed.01:25
cladamw2) ?01:25
wpwrak2) if they can keep the FPGA-RAM routes (or only need minor changes), then they or you should measure the lengths and check how far off we are01:25
wpwrak3) if there are excessive differences, we try to fix them01:26
wpwrakhow does that sound ?01:26
cladamwthree points sound okay. the fact i knew already in M1r4, the area under fpga must be changed since crowed reasons. so what I'd like to keep is the routes from RAM to fpga. I think our goal is focusing on those improvements which rc3 doesn't have. If the changes of RAM routes causes unexpected results, things go complex.01:29
wolfspraul8-layer pcb is also an option I think01:30
wolfspraulI have no problem with that as long as the costs are understood01:30
cladamwi know now is you're keeping at work on every piece of improvements in one time if as possible01:30
wpwrakcladamw: sure. if the RAM traces aren't overly horrible, there's no need to change them01:30
wolfspraulmore layers may also help us later if we have smaller boards, higher density balls, bigger chips, etc.01:31
wolfsprauland I think they help with better gnd, emi/signal integrity and similar as well - in general01:31
cladamwalso like wolfspraul always said to me, risks sometimes is good thing to discover likely.01:31
wolfspraulah wait :-)01:32
wolfspraulin business, risk = profit01:32
wolfspraulbut maybe that's just theory, I'm scratching my head... :-)01:32
wolfspraulgiven the risks we take, if it were that easy, we would all be multi-millionaires already :-)01:32
wpwraki'm just cautious to trust "it works" if the design is way off the specs. because then you don't control your design but the design controls you. and that's when the fear begins. the fear of making any significant change, because you don't know why your system works. we've met this kind of situation in a previous life, haven't we ? ;-)01:32
wolfsprauloh definitely01:32
cladamwso I'd really prefer change/or follow Micron's rules when a next generation or 8 layers then. :-)01:32
wolfspraulonce we understand something, once we look in a datasheet and see something is off, we have to investigate!01:33
wolfspraulmaybe that next-gen is r401:33
wolfspraulmemory performance is very important, as we have learnt01:33
wolfsprauland we have plans to support ddr3 etc in the future01:33
cladamwwpwrak, sure, one trusts "it works" but liked your points on "because there could also be nasties like one-in-a-billion bit errors"01:34
wolfspraulcladamw: I think 8-layer is an option, why not. depends on you.01:34
wpwrakDDR3 ought to be fun :) note that the design spec i found is from 2006. so we're not exactly talking about bleeding edge :)01:34
wolfspraulI can still reproduce m1 freezing by just leaving it rendering in simple mode. but in order to really make it reproducible, I need about a week now :-)01:34
cladamwwolfspraul, are you trying to say that M1r4 we can route it as 8-layer this time ?01:34
wolfspraulsure why not01:34
cladamwwow...big deal though. :-)01:35
wolfspraulif that makes the layout easier, 8 layer may be the better design/solution01:35
wpwrakwolfspraul: sounds like even more fun than the NOR troubles ;-)01:35
wolfspraultalk with the layout people01:35
wolfspraulI think more layers may make things easier, not harder01:35
cladamwwpwrak, wolfspraul now things go really fun. i like it to direct 8 layers. but i don't know if Sebastien likes or not. :-)01:36
wpwrakhehe :)01:36
wolfspraulyou prefer 8 layers?01:36
wolfspraulI don't think what the problem would be - especially if the layout people are comfortable with it and even prefer that!01:36
wolfspraulboards with more layers tend to be *easier* than those with less - or am I wrong?01:37
wpwrakthe "problem" would be that it would probably not make sense to try to carry over the old layout01:37
wolfspraulthe additional layers help with emi, integrity, better gnd. the only thing I would like to watch and understand well is cost.01:37
wpwrakbut i suspect that the potential for this is very limited anyway01:37
wolfspraulthe one thing I learn from professional layout people is how fast they are01:38
wolfspraulwithout any inside knowledge, I can guess they can redo the entire layout in 2-3 days01:38
wpwrakyes, one thing is labour saved. that may not be significant.01:38
cladamwsince from all reviews for couples months, we knew DVI routes and RAM routes (caused by crowed addings) which are two biggest things to worry. so a 8-layers can try to do great ground shielding layers. :-)01:38
wolfspraulyes, exactly01:38
wpwrakthe other thing is new mistakes avoided. that can of course be hairy.01:39
wpwrakyeah, better have some ground between DVI and RAM ;-)01:39
cladamwwpwrak, sure it indeed to have that, then no much worries.01:40
wolfspraulso why would anyone be opposed to 8-layer?01:40
cladamwso now the problem is can sebastien agree ? ;-)01:41
wpwrakwolfspraul: maybe mechanical stability. maybe cost. maybe some obscure parameters that get harder to manage. (thermal, dielectric, whatever)01:41
wolfspraulI want to understand the costs. the rc3 pcb cost 21 USD I think.01:41
wolfspraulwe made about 10001:41
wolfspraul1900 USD for 95 pcbs, something like that01:41
wolfspraulI think more layers makes things easier, for everybody.01:42
wolfspraulwe may make back any extra pcb costs in saved layout time alone.01:42
wolfspraulthe reason people (in the industry) prefer less layers is cost-reduction (!)01:43
cladamwokay, tomorrow I'll send new design files to house for evaluation on 6 and 8-layers cost firstly then feedback here.01:43
wpwraklet alone the debugging an overcrowded layout may need ;-)01:43
wolfspraulthe reason the hobbyists prefer less layers is because they are overwhelmed already, and try to remove any difficulty, whatever that may be01:43
wolfspraulso the motivation for 'less layers' is totally different01:43
wolfspraulin the industry, I think most people will agree with you more layers make things *easier*01:44
wpwrakwell, the limit for all-DIY is still 2 layers ;-)01:44
wolfspraulless layers = cost, risk01:44
wolfspraulbut you can save a little (pennies mostly), which you make back over large volumes01:44
wpwrakyeah. once the "M" stands for "Million", then we should worry about that :)01:44
cladamwwpwrak, ha DIYs are kinda also 'fun' industries.01:45
wolfspraulcladamw: would you agree with my description?01:45
wolfspraulI am super relaxed about 8-layer, I think it will make everybody's life easier.01:45
wolfspraulit may make the pcb a few USD more expensive, but at our volume that doesn't really matter compared to the advantages in design stability we get01:46
wolfspraulnow - if all is fine with 6-layer, then of course there may be no need to switch. that's why I say let's consult with the layout house over this.01:47
wpwraksounds good01:48
cladamwwolfspraul, some points agreed some are not. it depends on what things( adventures of 'sales' or 'tech' developments) we are concerning. ;-)01:49
cladamwsince i am not sure what we discussing now is good for M1, but maybe you can say me is F.U.D. though. hehe...;-)01:49
cladamwsurroundings among rising developments for execution/ease is yes good. ;-)01:51
wolfsprauldon't understand01:54
wolfspraulI think we agree on the next practical steps: go to layout house, see what they say about 6 vs 8 layer.01:55
cladamwsure. :-)01:55
wolfspraulmost likely they will say "both seem possible" (of course)01:55
wolfspraulalso I think you agree the reason the oem/odm industry prefers less layers is cost reduction01:55
wolfspraulevery layer first of all adds some cost, inevitably01:56
wolfspraulso naturally an oem/odm that tries to squeeze out every fraction of a penny will try to remove layers as well :-)01:56
cladamwhaha....we are their customer, they would say like that. let's see the costs thy give us later. :-)01:56
wolfspraulbut our reason is not cost reduction! our volume is too low01:56
wolfspraulwe must make decisions now that help us now01:57
wolfsprauland without cost reduction, I think 8-layer would normally be considered easier/more stable than a 6-layer design for our board01:57
wolfspraulbut let's see01:57
wolfspraulI think we are all roughly on the same page about this.01:57
wolfspraulcladamw: how many layers does a typical notebook mainboard have nowadays?01:59
wolfspraulI think it's still 12-14 or so?01:59
wolfspraulif it's that many - why? to keep different signals away safely?01:59
wolfspraula lot of phones I see have 8 layers02:00
wolfspraulI should check some wifi usb dongles, curious now02:01
cladamwAcer notebooks for 8-layers, I just called house to know.02:01
wolfspraulnice - thanks!02:05
kristianpaulwpwrak: oh indeed, looks odd and something missing02:25
kristianpaulyoutube video, now wee ne back to the past 10years and made the M1 revolution begin ;)02:26
wpwrakkristianpaul: oh. that was a long context switch ;-)02:26
wpwrakyup. M2 shall have built-in time travel :)02:26
kristianpaullong, sorry just arriving from work..02:27
kristianpaultraffic wasnt very good today :|02:27
kristianpaulperhaps just un-used white spacces02:27
kristianpauland lack of video mix and VJ interaction with it02:28
kristianpaulthey tought pre-recorded vide clip both music and video loops were all the thing02:28
wpwrakheh :) the joy of "live" performances :)02:29
Action: kristianpaul loves Jean Michel Jarre live performances02:30
kristianpauljust look this video, and noticed effects in the walls http://www.youtube.com/watch?v=XNIjDUSIOzY&feature=fvsr02:33
wpwrakyeah, they made a bit more of an effort :)02:35
wpwrakM1r4 will also have a laser02:35
wpwrak... in the rf keyboard :)02:35
kristianpaullaser, YEAH !02:36
wpwrakjapanese techno is fun. the crazy is strong in them. here's a song for caffeine addicts: http://www.youtube.com/watch?v=gZVPIJO88z002:54
wolfspraulwhat are the plans for m1 boomification now?02:54
wolfspraulshould we get started on the kicad transfer?02:55
wolfspraulI wouldn't mind firing up kicad and learning about schematics editing, I hope I can contribute a little...02:55
wpwrakare we done with the review ?02:55
wolfspraulseems like02:55
wolfspraulthat thread is messing up my email view :-)02:55
wolfspraultoo long!02:56
wpwrakyeah, the thread is a little complex ;-) maybe i should have started a new thread for each subsystem02:56
wolfspraulI'm really eager to get this boom thing going, efficient sourcing is so often overlooked in open hardware, it's not funny anymore02:57
wpwrakboom comes after the schematics. first we need to give it something to eat :)02:58
wpwrakand the new boom also isn't ready yet. maybe 1/3 done so far. the characteristics database should be usable soon. that one of the nastier bits.02:59
wpwrakah, and digi-key produced a snag as well. lemme find it ..03:00
wpwrake.g., this url should work in a browser: http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=yageo&x=0&y=003:02
wpwrakbut if you wget it, you get something weird. function decode_string(in_str) { return decodeURIComponent(in_str); } ... and then a lot of hex data. not entirely sure if this is some particularly clever bit of web design or if they're trying to obfuscate their query results03:04
wolfspraulhmm, I see03:10
wolfspraulI should ping them about boom, adding to todo03:10
cladamwwpwrak, all pages/sheets are done ! so now I'm going to combine them for all into final M1r4.03:12
wpwrakthe great finale ! :)03:12
cladamwI just read back log. Agreed on an email would be needed to include those seperate mail threads linked.03:14
wpwrakok. i'll do better the next time :)03:15
cladamwno, you did well already.  The threads are bit a messy since I edited subsystem(each sch sheet) only to corresponding your sub-reviews. :-)03:16
cladamwBut actually in my original design files are always kept as newest just generate sub-sheet pdf. :)03:17
cladamw(M1r4 final sch) http://downloads.qi-hardware.com/hardware/milkymist_one/sch/20120321/Milkymist%20One%20R4%20-%2020120321.pdf04:14
cladamw(M1r4 Bom) wiki bom is updated: http://en.qi-hardware.com/wiki/Milkymist_One_R4_BOM04:15
cladamwnext for me to clean up AD design files about each part's footprint libraries, some of them will let house to do not me though.04:17
wpwrakfootprints are fun ;-)04:18
cladamwsorry that about reviews to footprints, i did this way between house and me before.04:20
cladamwbut this time, i'll try to open it as possible, i'll find a way for this.04:20
wpwrakwould be cool. do they have a nice human-readable export format for footprints ?04:21
cladamwlike Y1/C259/new connectors etc...those footprints I still can't edit it for now. :(04:21
cladamwyeah...I'll try to know if there's export way to our list reviews.04:22
cladamwhehe...house doesn't have good review system, they just quick edit then sent to me for review their dimensions before.04:23
cladamwhouse here jobs as I co-worked with them, they are NOT responsible for accurately 'correct' to corresponding to datasheet's drawing. Always sent back to EE RD to 'confirm'04:24
wpwraksmart ;-)04:25
cladamwthis way is eastern businese doings, but not the way as now we're doing though. i know this is not good.04:25
wpwrakwell, doing it our way, they wouldn't be responsible for the footprints either :)04:26
cladamwbut I'll think another way to 'display', export and else to show out for reviews.04:26
cladamwso since from rc1 to rc3, all new changes for footprints are confirmed by me when house sent back. If i don't like then ask to modify back and forth, that's sometimes spending too long time. :(04:28
wpwrakcouldn't you just have edited the ones you didn't like yourself and sent them the corrected versions ?04:31
cladamwyeah, so far i can't, not i couldn't. :(04:36
cladamwif i can then i'll surely & directly myself for it. So i can only edit sch and sch libraries. :-)04:39
cladamwlike om has layout member, ee can't do edit footprint jobs but review only. :-O Here's east. :(04:43
wpwrakcladamw: but what's preventing you from editing footprints ? would the layout people not accept footprints from you ?06:00
cladamwno else can prevent me to edit footprints. also not from layout people. It's about me that to 'learn' AD for me is not the efficient way.06:03
cladamw1. can i learn it well as expected ?06:04
wpwrakaah, i see. okay :)06:04
cladamw2. is it worthy ?06:04
wpwrak1. sure. 2. perhaps not, since we're moving away from that anyway.06:05
wpwrakhave you used fped yes ?06:05
cladamw3. i am old now. well.....those are not the blocks if want to learn. But prefer to learn else open s/w step by step, but still slow though for projects.06:06
cladamw(fped) ? seems it's your smart tool again. i remembered there's some for footprints too ?06:07
wpwrakyes, fped is my footprint editor06:08
wpwraki hope you'll like it. it's not very complicated once you get used to the concept06:09
wpwrakand it's good at automating repetitive work :)06:09
wpwrakalas, it won't help us with M1r406:10
cladamwbut will help for M1r4 with KiCad version ?06:11
cladamwso an output file from fped can be imported into KiCad, right ?06:13
wpwrakif we decide to also do the layout of M1r4 in kicad, yes06:13
wpwrakyes, fped exports its footprint in the format kicad uses06:14
cladamwnice. so how to install it ? just git clone, and type 'make' ?06:14
wpwrakyou may need to install a few packages first06:15
wpwrakapt-get install flex bison imagemagick xfig libgtk2.0-dev06:16
wpwrakthat should do the trick06:16
wpwrakthen you can make it06:16
cladamwalright, but i think i can use it later, since we have to finish house work firstly.06:17
cladamwmoment ... let me try to install now.06:17
wpwraksure. you won't need this for weeks if not months ;-) i was just curious if you had already used it (e.g., in the context of Xue)06:18
cladamw_aha...i git cloned Xue before to review, but didn't know it used fped already ?06:19
cladamw_yeah...many err after directly 'make' . :-)06:21
wpwrakwhat's the first error ?06:21
wpwrakdid you  apt-get install libgtk2.0-dev  ?06:25
wpwraki.e., run the command i showed above06:25
cladamw_yes, it's running...06:26
wpwrakyou need all the packages i listed. they aren't installed by ubuntu by default06:26
wpwrakgood :)06:26
cladamw_done !06:27
cladamw_so click or run which file ?06:27
wpwrakif you want to access an existing file,  fped <filename>06:28
cladamw_ha...i run it. ! :-)06:28
wpwrakelse,you can try the example on http://downloads.qi-hardware.com/people/werner/fped/gui.html06:28
cladamw_ha...okay I'll learn your gui, so there's no icon in Applications ?06:29
wpwrakicon ?06:31
cladamw_I mean Ubuntu's "Applications" -> "Electronic" -> "KiCad" ? if no, forget it. ;-)06:33
wpwrakah no. the command line is your friend ;-)06:34
wpwrakand there's no "open" anyway :)06:34
cladamw_yeah...forget it. terminal is my friend recently. :)06:34
wpwrakah, one warning: fped doesn't warn you if you made changes and try to quit without saving. so always save before quitting (unless you want to discard your changes)06:35
cladamw_aha...good and important warn. ;-)06:36
wpwrakyou'll find footprints in the qi-hw projects kicad-libs, ben-wpan, wernermisc, etc. the files are called *.fpd06:36
cladamw_so we will use fped for M1 soon. :-)06:37
cladamw_yeah...to use those you've done already.06:37
wpwrakbut first the schematics :)06:41
wpwrakanyway, i'll take a nap now. and then i'll figure out how to get cups to print the M1 schematics ... i hate upgrades :-(06:42
cladamw_alright, sleep first. :-)06:43
cladamw_wait, do you want me to collect sub-system/sheets into one mail ? and also inlcude latest final M1r4 ?06:45
cladamw_i mean i go for collect those sub-reviews url links into one.06:46
cladamw_well...you sleep first though.  thanks. :)06:47
lekernelwpwrak: if you want to try the high speed DDR (since you seem to have little trust in the current design, let's build more data) you can use milkymist-ng and the ddrrd/ddrwr commands08:09
lekernelwpwrak: they use some "bit banging" from software to read/write the memory08:09
lekerneland the data bursts are DDR36608:10
GitHub171[milkymist] sbourdeauducq pushed 2 new commits to master: https://github.com/milkymist/milkymist/compare/5487292...1bd8ff008:17
GitHub171[milkymist/master] flterm: add speed option - Michael Walle08:17
GitHub171[milkymist/master] flterm: report usage errors to the user - Michael Walle08:17
GitHub98[milkymist-ng] sbourdeauducq pushed 1 new commit to master: http://git.io/FtPdGA08:18
GitHub98[milkymist-ng/master] tools: new flterm - Sebastien Bourdeauducq08:18
GitHub41[milkymist] sbourdeauducq pushed 1 new commit to master: https://github.com/milkymist/milkymist/commit/685696729aeb4b796420467c020586ea2a1e713908:19
GitHub41[milkymist/master] Bump version numbers - Sebastien Bourdeauducq08:19
lekernelmwalle: thanks for the patches!08:21
wpwrakcladamw: (one mail) no no ... that was about threading. it would have been better if i had started a new thread for each subsystem. that's all. no need to recompile what's there - we now have the updated schematics for this :)10:53
cladamwwpwrak, good morning ! no need a notification about final M1r4 mail to list ?10:56
cladamwsince I'm preparing all design files and layout note for house. :-)10:57
wpwraklekernel: let's wait with this until we have the first M1r4 prototypes. if there was anything obviously wrong already in M1rc3, you'd hit it yourself. and a proper test will take some time (and preparation), so that's better done just once.10:57
wpwrakcladamw: (notification) well, if you think it's useful and not a lot of extra work, sure :)10:58
lekernelthen let's not mess with the routing in R410:59
wpwrakcladamw: and yes, it's good to send an announcement of the latest version of the whole schematics10:59
lekernelwe need to support the current boards anyway10:59
wpwraklekernel: i think the routing will be messed with anyway. i don't see much of a chance for a 1:1 copy11:00
lekernelin the sdram region? why?11:00
wpwraksmall things. move that component a little, make room for some other traces here, go to a different layer there, etc. before you know you have to reroute the whole thing11:01
wpwrakso they may as well match the trace lengths while they're at it11:02
cladamwwpwrak, okay, I'lll send a final latest R4 of whole schematics for announcement.11:03
wpwrakit also depends on how crowded the layout already it. if there's a lot of room, maybe you can get away with copying. but i doubt it. there are just too many changes.11:04
lekernelthen remove some of those changes11:04
wpwrakthat doesn't have to mean that they'd do something radically different, just lay the routes again11:04
lekernelthe last thing I want is go through another round of SDRAM timing tinkering, especially if then we have pre-R4/R4 differences that need to be supported e.g. with different bitstreams11:05
wpwrakit doesn't work like that ;-) of course they CAN preserve everything you specify 1:1. make a gerber copy even and connect into it. it just makes the rest of the work harder.11:06
wpwrakdid you make optimizations specifically to deal with skew ?11:07
lekerneland I don't want to11:07
wpwrakexactly my opinion ;-)11:07
lekernelexcept using the fast I/O clocks and registers ofc11:07
wpwrakand you're making a fine example for why it's important to stick to those design recommendations :) because if you don't, you lose control. and you're already afraid of what may happen.11:08
wpwrakregister OFC ?11:08
lekernelI'm not afraid, but life's simply too short to do this.11:09
lekernelyes, I'm using the dedicated I/O registers (in the SERDES) which have good timing11:11
wpwrakin the sense of the FPGA not adding skew of its own ?11:11
lekernelyes, and with timing that doesn't depend on the P&R heuristics11:12
wpwrakall that sounds as if a more precise layout could only help but not make things worse11:13
lekerneltheoretically yes11:13
lekernelbut fixing a working system is almost always a bad idea11:14
wpwrakdid you read the three points i suggested to adam ? 1) let they layout people try to keep things (if that makes sense to them) 2) get a report of trace lengths. 3) see if anything sticks out as particularly bad. i wouldn't worry about a 501 mil difference anywhere. but, say, 1000 mil would be suspicious11:16
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