#qi-hardware IRC log for Sunday, 2012-10-21

whitequarkroh: hey, do you recall our discussion about smartphones? I've finally determined that for myself00:27
whitequarkif, and only if, you use your smartphone like a dumbphone, it will easily live for a week. I just confirmed that.00:27
whitequarkthe problem is, why the hell would you want to do that if you have a smartphone.00:27
Action: kristianpaul is using dumbphones since 200000:31
kristianpauland at that time a palm m100 ( the PDA thing)00:33
kristianpauland my 1.2M camera of course :)00:34
whitequarkkristianpaul: it's a nice thing to have one gadget which works as a music player + gps navigation device + a camera (SGS2 has a camera which is on par with cheap "discrete" ones) + a dumbphone.00:34
whitequarknot to mention occasional web browsing, through it's non-vital.00:35
whitequarkthe point is, ARMs _are_ energy-hungry, and they can convert electricity to heat very fast. they just sleep very well.00:36
kristianpaulsame reason i dont buy swiss knife...00:36
kristianpaulso yes you could leave with it, just need to take the desition 00:37
kristianpaulsame reason you dont reply i guess al your mail in your smartphone 00:37
kristianpauli hope you dont :)00:37
whitequarkwell, do you keep a knife, screwdriver set, pliers, etc with yourself at all times?00:38
whitequarkI need gps once in a month, when I'm lost, and camera maybe once a week, and so on00:38
whitequarkI simply don't have the brainpower to remember if I will need a particular function at a particular day00:39
whitequarkheck, it was hard enough to remember not to forget the phone itself at home.00:39
whitequarkkristianpaul: I would reply to a sizable part of my mail on my smartphone, if not for the virtual keyboard. Unfortunately no one makes good physical keyboards now00:40
whitequarkwhich is kinda disappointing, especially given the fact that Android has _very_ good support for keyboard and mice00:40
wpwrakthe world clearly needs new input devices. how about position-of-the-tongue for picking a key ? swallow to enter, burp to delete.01:41
wpwrakkristianpaul: here, dumbphones since around 1996. they get the job done, what more can you ask for ? :)01:43
whitequarkwpwrak: touchscreens are great for lots of things02:30
whitequarkI'd say for more things you would like to do with a smartphone, except writing text.02:30
Action: xiangfu try to use the oven for soldering the chip now03:32
xiangfuthe 4 steps will be:03:32
xiangfu    Set to 90C for 3 minutes to preheat03:32
xiangfu    Set to 150C for 1 minute for thermal soak.03:32
xiangfu    Set to 210C for 1 minute for reflow. This results in a Tal of about 15 seconds.03:32
xiangfu    Turn off oven, open door, and cool to ambient with room air03:32
xiangfubase on azonenberg's blog03:33
wolfspraulwow, oven!03:33
wolfspraulyou got a random cheap chinese mini-oven? how much did you pay?03:34
xiangfuno. I buy a ACA oven. 270RMB.03:35
xiangfuit have 4 heating pipes.03:35
xiangfu<250RMB. all is 2 heating pipes.03:36
xiangfuthis one: http://www.360buy.com/product/150841.html03:37
xiangfuwolfspraul, I  already burned a ftg256 chip by using hot air :(03:38
wolfspraulspeed up your discoveries :-)03:38
wolfspraulbuy another 10 of them03:38
wolfspraulthat's why we work with a 7 USD chip now, not a 70 USD chip...03:39
wolfspraulyou should just try in series right away, different durations etc.03:39
wolfspraulunless the results are extremely obvious (smelly), you probably need 2 or 3 of the better attempts to understand yield issues03:40
wolfspraulanyway, have fun! :-)03:40
wolfspraula little Sunday cooking03:40
wolfspraulchip brunch03:40
wolfspraulwatch the fumes btw03:40
wolfspraulif possible do this near a big and open window, ideally outside but maybe that's difficult03:41
xiangfuI will try to use the broken chip first. 03:41
wolfspraulespecially when you burn a lot you may create a lot of fumes03:41
xiangfutoday is cold. I goto one small room. close the door. open the window. :)03:41
wolfspraulyes good03:42
wolfspraulthose fumes can be really bad03:42
wolfspraulespecially if you do one experiment after another, and day after day03:42
xiangfuyes. 03:42
wolfspraulI just looked out my window... made me thinking whether OPENING the window is such a good idea :-)03:43
wolfspraulbut ok...03:43
wolfspraulputting the typical Beijing air aside, it's still true :-)03:43
xiangfube back in 10 mins. try my first chip-cooking. :)03:43
wolfspraulgood luck03:43
xiangfutotally failed. http://downloads.openmobilefree.net/tmp/IMG_1393.JPG04:08
xiangfuI use hot air on left one.04:09
xiangfuuse oven on right one. 04:09
wolfspraulfailed = the soldering didn't happen?04:13
wolfspraulthe right one looks nicely toasted though :-)04:13
wolfspraulbuy more chips and boards, maybe 20 or so04:13
xiangfu(failed = the soldering didn't happen?) yes.04:13
xiangfuI guess I miss up the temperature. 04:14
wolfspraulnot sure how accurate the setting is, or to reach/hold it etc.04:15
wolfspraula precise measuring is also difficult04:15
wolfspraultoo bad you can't just program the whole world04:15
wolfspraulmaybe too warm04:16
wolfspraulof course a chinese heating computer would immediately and happily return with "19.5000 exactly reached, have a nice day"04:17
xiangfuexactly. 04:22
xiangfuI made 10 of those PCB. in parallel. I try to improve the pcb design. I found it's really not easy route more wires in 2 layers.04:22
xiangfuthe youtube or other example videos/documents  are all simple chips. simple design.04:23
xiangfuthe azonenberg04:23
xiangfuthe azonenberg's board is good reference for learning.04:24
xiangfubbl, lunch time.04:24
wolfspraulimagine those would be sample chips from our own chip design04:52
wolfspraullet's say we got 10, after waiting for 2 months04:53
wolfspraulthat would be painful to burn! :-)04:53
wolfspraulby then we better have figured this out... :-)04:53
wpwrakhmm, that pcb's problems still start a long way before the soldering ...08:19
wpwrakat least with a pcb (as opposed to a ball of wires) it's easier to see what's wrong :)08:20
wpwrakxiangfu: nicely cooked pcb :)09:00
wpwrakthe silk screen varies quite a bit with respect to the copper. you'll probably have to find a more precise fab when you get to doing more serious things.09:02
wpwrakabout the layout: you can make your life easier by routing ground outside the chip, not under it. e.g., if you make a U-shaped ground trace (include connectors and oscillator), then you need only relatively short traces that go under the chip. this lowers the risk of make unintended contacts.09:06
wpwrakthen, you only have one silo cap at the power connector, but no bypass caps at the fpga. the longest distance between ground and cap is about 50 mm, which is a bit excessive.09:07
wpwrakthe number of connections to power is also suspicious. there should be more of them.09:11
wpwrakand another one: P1 ground should connect to P2 ground via a trace, not through the chip.09:12
wpwrakthe aspect ratio (hole to ring diameter) of the holes for the connectors seems quite small, especially if we consider that your fab is not very precise. maybe make it a bit bigger.09:14
Introhi gargom10:49
gargonintro: hi10:50
gargonif someone interested, I found an interesting article about chip/pcb cooking with a toaster like appliance: http://avr.tavir.hu/modules.php?name=Content&pa=showpage&pid=11810:51
wpwraki like the triac :) the rest of the circuit seems over-engineered.12:31
wpwrakwhy not use a cheap AVR with V-USB. that solves: 1) power supply, 2) controls, 3) indicators, 4) communication with modern hosts.12:32
wpwrakof course, you need some confidence in having gotten the galvanic separation right. the price of failure is a PC :)12:34
rohwpwrak: the moc series is nice.. optoisolated hv-switches14:24
wpwrakjust integration of the "large" triac is missing14:26
kristianpaultriac are live saving, even more if you add an optocoupler 14:35
rohwpwrak: the moc is the driver as far as i can see.. but there are solid-state-switches which have all that integrated14:36
rohzero-crossing, optoisolated line switches14:36
wpwrakdo you know one ?14:36
wpwrakthe problem with external components is that anything that's rated for mains voltage is bulky, often just to obtain a large enough air gap. when integrated, such issues disappear.14:38
rohjust an example. there are more with different ratings14:38
rohyou can directly drive those from the avr, and connect to ac ;)14:39
wpwrakah, a module. i was hoping for a chip :)14:39
rohnope... there are some chips, maybe even in the moc series with integrated triac14:39
rohi guess these sil solid state relays are more what you want14:40
wpwrakat that size, the module should also supply power to the outside :)14:40
rohits the same case size for 40A14:41
rohmechanics matter when it comes to power rating ;)14:41
rohwell.. there are readymade kits for driving a toasteroven or similar appliances to defined temperatures ;)14:43
wpwrakthe one at sparkfun looks much nicer :) let's see if digi-key have something like that ..14:45
wpwrakhmm, all quite expensive14:51
rohdigikey is expensive14:52
wpwrakbut factor of 6 ? the cheapest that can handle >= 400 V and >= 8 A are USD 24.76 @ 100. (these are actually 530 V 25 A, but the 8 A models are even more expensive)14:54
wpwrakwell, this one is still reasonable, though also more expensive (800V 5A, USD 6.05 @ 100): http://www.clare.com/home/pdfs.nsf/www/CPC1998.pdf/$file/CPC1998.pdf14:57
rohwell.. i dont buy at dk.. dunno whats their issue15:03
wpwrakah. they also have the sharp part. but listed as "120 V". price similar/better to/than sparkfun:  5.10 @ 1 vs. 4.95, 4.08 @ 10 vs. 4.46, 3.37 @ 100 vs. 3.9615:13
wpwraknow that makes a lot of sense. alas, the "240 V" part (S208T02) is "call for price"15:14
rohwpwrak: yeah. i guess there are some dozend of similar devices17:56
wpwrakyeah, seems that i'm not the only one who likes their circuits to be compact :)18:24
qi-botThe build was successful: http://fidelio.qi-hardware.com/~xiangfu/build-nanonote/openwrt-xburst.minimal-20121020-1228 21:04
--- Mon Oct 22 201200:00

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