#qi-hardware IRC log for Monday, 2012-01-02

wolfspra1lcladamw: good morning in the new year! ;-)00:46
cladamwwolfspra1l, hi good morning in 2012 .:-)01:09
wolfspraulI tried building kicad on my new i7-2670QM quad-core and finally wanted to see make -j in action...20:35
wolfspraulhere's what I got: make 9.01 min; -j2 4.30 min; -j4 3.24 min; -j6 3.10 min; -j8 3.06 min20:36
wolfspraulso I guess from now on I will always try either -j8 or -j4 first, hopefully won't run into too many build weaknesses...20:37
wpwrakhehe :-)20:40
wpwrakyes, make -j saves quite a lot of time. if you have plenty of RAM to cache the whole tree, even better20:41
viricyou can build with parallelism based on the system load20:57
wolfspraulviric: how?21:35
wpwrakwith -l perhaps ?21:40
wpwrakbut most machines have no significant background load anyway. well, except for perhaps some runaway flash player ...21:41
wpwraki have a script called "np" that just does  killall npviewer.bin nspluginviewer  incredibly handy for keeping a healthy low load average :)21:42
lars_wolfspraul:  if you have 8 cpus -j921:45
wolfspraulhe. thanks! trying that same build as before with -j9 brought it to 2.38 min (without any other load), quite a bit faster than -j822:01
wolfspraulcould be caching or filesystem related though, who knows. will go with -j9 from now on...22:01
Aylatry with -j6422:02
Aylamaybe it'll compile in less than a minute :)22:02
whitequarkwpwrak: I used to have `killall -9 python' in crontab. It worked just as well22:49
whitequarkat least on ubuntu22:49
whitequarkdoes anyone know an open standard for low-power, low-complexity wireless sensor networks?23:16
whitequarkpreferably less complex than both zigbee and 6lowpan23:16
wpwrakyou can always do your own on top of 802.15.4 :)23:17
whitequarki.e. something where all the stack can be fit in a single Arduino (no, I'm not going to use arduinos, but that describes the limit)23:17
wpwrak(like i did with dirtpan. though i wouldn't call that a "standard" :)23:18
wpwrak(or simpler)23:18
whitequarkcan you suggest any plain 802.15.4 modules? i.e. not zigbee ones23:18
whitequarkoh well, there's even a dedicated wikipedia page on the topic: http://en.wikipedia.org/wiki/Comparison_of_802.15.4_radio_modules23:19
wpwrakdefine "module" :)23:21
wpwrakthere's of course the atben/atusb design ...23:21
whitequarkanything which has SPI input and ready-to-use PCB/chip antenna23:22
whitequark_and_ has a low cost23:22
wpwrakatben is pretty close. you'll make you own pcb anyway, right ?23:22
wpwrakjust reuse the design23:22
whitequarkhow hard do you think it will be to integrate the design on my own PCB as a part?23:23
whitequarkit's RF and stuff23:23
wpwrakdepends. is your pcb 0.8 mm ?23:23
whitequarkand I have zero experience in RF and no instruments which I can use to debug RF problems23:23
wpwrakinstruments are useful to have. no matter how you approach it. also pre-built modules can run into all sorts of problems. without at least a spectrum analyzer or similar, you'll never know if your design has troubles23:25
whitequarkthe prototyping service I'm currently using (iteadstudio.com) has the 0.8mm variant, and I think I can adapt all other stuff to that23:25
whitequarkwell, I can't afford a spectrum analyzer, I think23:26
wpwrakif your pcb is 1.6 mm, you'd have to adjust the pcb antenna of atben. that's unfortunately a bit of trial and error (and measurements)23:26
whitequarkthey're expensive as hell23:26
wpwrakyes. a usrp is often cheaper. but still not "cheap"23:26
whitequarkNordic semiconductor modules are cheaper than $523:26
wpwrakbut sometimes you can find places/friends who can let you use their equipment. universities can be great places for that.23:26
whitequarkbut they're also feature vendor lock-in23:27
wpwrakwhat range requirements to you have ? and how compliant to emission standards does it have to be ?23:27
whitequarkI'm looking at all of the emerging open hardware projects on the topic ("internet of things" and similar stuff), and I've finally decided that's not an option23:27
wpwrakso you don't want to do this after all ?23:28
whitequarkI was talking about vendor lock-in23:28
whitequarknot the whole project23:28
wpwrakah, vendor lock-in always sucks :)23:28
whitequark(range) 20m in a house with maybe one or two reinforced concrete walls23:29
wpwrakit may make the beancounters in the back office happy, but they're not the engineers :)23:29
wpwrakhmm. then you need a power amp.23:29
whitequark(compliance) I don't care unless it's emitting two times more than my WiFi AP. No one will notice anyway23:29
whitequarkI am not going to sell that commercially, nor I want to do anything with FCC (yet). It's just a pet project just for me23:30
wpwrakdon't underestimate the fragility of wlan ;-) even with the meager 2 mW my atben/atusb can put into the air, i can mess up my wlan quite badly ;-)23:30
whitequarkoh well.23:30
wpwrakthe solution is of course not to make it hog the same channel23:30
whitequarkmy wlan disrupts the performance of my Bluetooth mouse, so I've decided to move it to 5GHz spectrum, as it's finally allowed in Russia23:31
wpwrakbut if i'm in a mean mood, i can quite easily jam my wlan with it23:31
wpwrakokay, i'm all 2.4 GHz :)23:31
whitequarkbut I have neighbors...23:31
whitequarkI never thought of wlan to be so fragile.23:32
wpwrakif you implement the usual channel access protocols, then you should be fine23:32
wpwrakit will clash every once in a while, but nobody will notice23:32
whitequarkdoes 802.15.4 phy/mac include that already?23:33
whitequarkI bet it does23:33
wpwrakmy jamming happens when i deliberately make it misbehave (but still at a fraction of the power)23:33
wpwrakyes, that's normally there23:33
whitequarkit's fine then23:33
whitequark(range) wait, I think I screwed up23:33
whitequarkthe range is about circle, not area23:34
Action: whitequark gets his tape measure23:34
wpwrakif you can do with 10 m free space or maybe 2-3 m through "nasty" walls, the at86rf231 is a good chip to start with. documentation is quite complete. and you have an existing project you can fork from.23:34
wpwrakfor a larger range, you'd have to add an rf amp, though23:34
wpwrakrange is radius :)23:35
whitequarkyeah :)23:36
wpwrak(atben/atusb) plus, you can get usb dongles with known to be good specs. or, if you have a ben, atben. that's even cheaper.23:36
whitequarkI don't have any two points more distant than 6m23:36
whitequarkand there are no concrete walls inside anyway23:37
wpwrakthat way, you can quickly compare performance. the production tests process can detect some RF issues, using just atben and atusb: http://downloads.qi-hardware.com/people/werner/wpan/prod/index.html23:37
whitequarkso I think that atben-based design will work here23:37
whitequarkhm, interesting23:38
wpwraki got okay reception with about 5 m through a wall. so yes, it may work23:39
wpwrakwhat makes a big difference is where you locate those big bags of water, called "people"23:39
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