arm-netbook December 2014

arm-netbook@lists.phcomp.co.uk

11 participants
12 discussions

tablet casework prototype done
by Luke Kenneth Casson Leighton 31 Dec '14

31 Dec '14

http://rhombus-tech.net/community_ideas/kde_tablet/news/ the mendel90 printer is working really well, and was absolutely worth it to use for prototyping of casework. the 7in tablet project is now being done as an open hardware project, under the GPLv3+. files are available at http://hands.com/~lkcl/eoma/kde_tablet with a preliminary casework finished that has been prepared in conjunction with the pcb layout, work can proceed to finalise the pcb and then send it off for assembly. there are a couple of risky areas on the tablet pcb, due to datasheets and app notes simply not being available: the usb audio and the usb camera IC. these are a CM108AH and a Vi Micro VC0345 respectively. perhaps prior to sending off this PCB it may be worthwhile tracking down small USB devices with those chipsets in, in order to inspect them and check their PCB layout. however if anyone already _has_ a USB audio dongle with a CM108AH or a USB camera with a VC0345 chipset please do say so as i would greatly appreciate some hi-res photos of the PCB, both sides. l.

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[Arm-netbook] http://rhombus-tech.net/community_ideas/kde_tablet/news/
by Luke Kenneth Casson Leighton 22 Dec '14

22 Dec '14

started on a first revision of the tablet casework, as a pyopenscad program, using a blender-exported STL as the "ghost" template to work out how the case should surround the parts. it's done as layers so may either be made of wooden laminates or 3D printed and assembled using screws/bolts. l.

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3d printed tablet casework
by Luke Kenneth Casson Leighton 21 Dec '14

21 Dec '14

http://rhombus-tech.net/community_ideas/kde_tablet/news/ turned out okay for a first print. lots of thought required, as 3d printing of parts to use as laminates is not entirely satisfactory. l.

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Unsubscribe from the mailing list
by sahil mehta 17 Dec '14

17 Dec '14

Hi, Kindly un-subscribe this mail id from the mailing list. Thanks

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EOMA68-IC3128 revision 2 back from assembly and is working
by Luke Kenneth Casson Leighton 17 Dec '14

17 Dec '14

http://rhombus-tech.net/icubecorp/IC1T/news/ no hardware faults found, which is fantastic. they have not been sent back to me yet so i have to run some tests here first but this looks like these cpu cards (which are FSF Endorseable) may be added to the crowdfunding campaign. hooray. l.

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tablet rev 3.2 layout
by Luke Kenneth Casson Leighton 16 Dec '14

16 Dec '14

http://rhombus-tech.net/community_ideas/kde_tablet/news/ well it's a fixed PCB size, doesn't have to be a split design, but there's no possibility of sharing this across 2 or more designs. because of that i've cut out the extra components. still working on getting the layout right: the current issue is that the LCD is taller so obscures the middle-centred camera. that means the camera needs to move to the corner. it's an almost never-ending series of details, aaaaaaa!

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tablet re-re-design
by Luke Kenneth Casson Leighton 12 Dec '14

12 Dec '14

ok so i tried the new layout... _after_ joining all the tracks up of course... and unnnfortunately the cpu card slot is so far down that the battery is squashed badly at the bottom (long) end and is far too small. so... aaaaaaagh! i have to begin again :) next attempt will be to turn the cpu card round 180 degrees (so it comes out on the right). ah all good fun...

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hannstar LCDs LED backlight circuit
by Luke Kenneth Casson Leighton 10 Dec '14

10 Dec '14

On Tue, Dec 9, 2014 at 8:49 AM, joem <joem(a)martindale-electric.co.uk> wrote: > On Mon, 2014-12-08 at 15:45 +0000, Luke Kenneth Casson Leighton wrote: > >> ... *deep breath*... but.... hold everything, i've never been a great >> fan of the 1024x600 LCD panels > > hmmm... thinks odroid-vu > http://www.hardkernel.com/main/products/prdt_info.php?g_code=G140383714860 > > Miniature HDMI monitor for $120. > I bought one. If there were more of these things around > with variety then lessens need for fixed screen. which reminds me: i need to work out a circuit for driving the LCD backlight. does anyone have e.g. one of these: http://www.adafruit.com/products/1931 i need an example circuit to work from: the one that i have uses the SY7201 and it is designed to pulse the LEDs, whereas the Hannstar LCDs have their own dedicated LED backlight PWM input. l.

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Why EOMA68 will advance both free software and free hardware « Nico Rikken
by Alexander Stephen Thomas Ross 09 Dec '14

09 Dec '14

http://nicorikken.eu/blog/why-eoma68-will-advance-both-free-software-and-fr…

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flying squirrel tablet
by Luke Kenneth Casson Leighton 07 Dec '14

07 Dec '14

time for a bit of a rant :) i've been working on the tablet PCB now for... literally months over the past year or more, and i can't quite believe that every time i look at it i find something - yet another thing - that needs fixing or improving. the latest was noticing that NMI# from the tablet's AXP209 wasn't connected to one of the EINTs on the EOMA68 connector, and noticing that 18-pin RGB/TTL with the 8.9in LCD (only 3 lane LVDS) is incompatible with 24-pin RGB/TTL of the 7in LCD (4 lane LVDS). so, goodbye all the resistors for selecting different panels, and then i noticed that the power tracks were crossing the LVDS lines so had to completely reorganise those. i also noticed that the SD/MMC needed moving upwards a bit (so that SDcards could be poked into the case and actually... y'know... lock?), and... ... well, it's just a heck of a lot of detailed work and i'm just... amazed that there's so much to do! oh - one other hilarious thing: i tracked down a company that makes a TI SN75LVDS83b.... the name is *not* texas instruments, it's novatek :) it's the NT7181 and it's literally identical. even the ability to switch TTL levels so that it's 1.8, 2.5 and 3.3v TTL compatible depending on input voltage. anyway it's kiinda fun... l.

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arm-netbook December 2014