EOMA68 Libre 15.6in Laptop

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30 Sep 2016: EOMA68 Libre 15.6in Laptop PCB2 Revision 2

After reworking PCB1 and PCB2, work on a complete redesign of PCB3 began. Jakub kindly did an enormous amount of research into appropriate components, here, and his company mlab.cz actually releases all their CAD designs as Libre-licensed KiCAD. From his work and the research he's done, he's been able to steer the direction and component selection to near exclusive use of Texas Instruments parts. Texas Instruments has a reputation for reliability and the comprehensiveness of their documentation, so in retrospect this outcome could easily have been predicted.

This last PCB is the one where the most care has to be taken, as mistakes could result in fires or explosions. Many engineers simply will not work with such designs as public ongoing releases as a result, and some even refuse to sell such boards to individuals. Users are therefore expected to take responsibility for helping out and for making their own decisions.

The new revision is 5in long (which increases heat dissipation) and contains a buck/boost converter to bring the battery output voltage up to 5.0 volts. There are actually two 5V outputs: one for the main electronics (USB, speakers, LCD backlight) and one for the EOMA68 Card. The latter is two-way reversible which is why the bq24193 has to be used, as it is a fully "OTG" compliant charger IC. These parts have been selected because the output can be up to 4A @ 5V (20 watts), so a lot of care and attention is needed here.

The video below contains a walkthrough from the schematics to the PCB layout through to the 3D CAD indicating the relationship to surrounding parts. This complex inter-dependence serves to once again emphasise how critical it is that the entire laptop be developed holistically (and why re-using existing laptop casework is totally unrealistic). Changing the length of PCB3 required a change to 3 casework parts and a re-order of the cables to the other 2 PCBs. Using different ICs requires different pinouts (different functions available) such that the GPIO changes, possibly even the size of the connectors required, such that the other PCBs now need to be changed, and the STM32F072 firmware also needs changing. It's a massive chain of knock-on effects, any one of which, amazingly, could result in a near-total internal redesign.

Posted Fri Sep 30 06:31:40 2016

Archive

Crowdsupply Campaign launches
Posted Fri Aug 5 22:41:48 2016
EOMA68 Libre 15.6in Laptop casework completed
Posted Wed Mar 2 12:43:43 2016
laptop 15in pics.tgz
Posted Wed Mar 2 12:11:45 2016
EOMA68 Libre 15.6in Laptop bamboo panels
Posted Fri Feb 5 13:42:03 2016
EOMA68 Libre 15.6in Laptop partially assembled
Posted Wed Jan 20 16:29:51 2016
EOMA68 Libre 15.6in Laptop parts pre assembly
Posted Tue Jan 19 15:00:19 2016
Boards walkthrough post wiring
Posted Sun Jan 3 14:06:55 2016
Component walkthrough pre assembly
Posted Sun Jan 3 13:58:04 2016
PCB2 video prototype keyboard demo
Posted Sat Jan 2 15:48:10 2016
PCB2 prototype functional keyboard matrix
Posted Sat Dec 26 22:09:50 2015
Chicony keyboard matrix reverse engineering
Posted Thu Dec 24 19:43:17 2015
PCB1 LCD operational 14dec2015
Posted Mon Dec 14 21:42:31 2015
PCB2 prototype progress 10dec2015
Posted Thu Dec 10 16:34:42 2015
PCB1 LCD semi operational 01dec2015
Posted Tue Dec 1 15:51:05 2015
PCB3 prototype arrives 15oct2015
Posted Sat Oct 17 09:25:30 2015
PCB2 prototype progress 14oct2015
Posted Thu Oct 15 18:10:26 2015
PCB2 prototype progress 05oct2015
Posted Mon Oct 5 12:56:25 2015
PCB1 prototype progress 26sep2015
Posted Sun Sep 27 16:04:02 2015
PCB Revision 1 prototype 17sep2015
Posted Thu Sep 17 18:11:31 2015
PCB Revision 1 design progress 20 Aug 2015
Posted Thu Aug 20 16:54:42 2015
Casework first prototype completed 07 Aug 2015
Posted Fri Aug 7 17:12:46 2015
Casework progress 09 July 2015
Posted Thu Jul 9 14:50:31 2015
Casework progress 05 July 2015
Posted Sun Jul 5 17:24:54 2015
Casework progress July 2015
Posted Wed Jul 1 20:22:28 2015
Casework progress video June 2015
Posted Wed Jul 1 20:22:28 2015
PCB1 Support
Posted Thu Jun 4 10:26:26 2015
Casework progress June 2015
Posted Tue Jun 2 17:53:48 2015
Casework progress May 2015
Posted Thu May 14 17:06:59 2015
2nd revision progress
Posted Mon May 4 11:31:37 2015
Casework progress
Posted Tue Jan 13 23:00:21 2015
Specifications Developed
Posted Tue Jan 13 23:00:21 2015