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Not actual Pi Day recap, was: I didn't think I'd be around ... also free TV

4 of us there.  

Juan working on Linux install on old Pentium M laptop.  Booting USB failed with error 
PAE required.  Error message suggested booting with forcepae option which worked.  
From Wikipedia we find the early Pentium have PAE support but don't advertise it hence 
forcepae option.  

Peter was working on a Samsung tablet that is boot looping.  He tried to reload the OS by using a Samsung utility called ODIN.  But no luck this time.  Peter thinks there is a problem with the partitioning of the internal storage.  There is an option to redo partitioning in ODIN.  So there may be some more things to try.  
Also now I see there is an open source alternative to ODIN called Heimdall:  https://glassechidna.com.au/heimdall/

Bob and I working on interfacing laptop lcd with a controller board.  I have an lvds to 
vga board and Bob has a lvds tv board (vga, hdmi, component inputs)  
But neither of us had the right cable.  Confusing that both our boards have power on pin 1 
the data sheets for the panels have pin1 as ground.  Actually looking at the datasheets of different panels I see basically the same pinout.  
This link: https://www.badcaps.net/forum/showthread.php?t=80477 
Quoting user Piernov: 
[TLDR:  lcd panels are interchangeable as long as you match size, interface (lvds or edp), connector size and/or placement, backlight type (ccfl or led)]

     "It is possible to replace a LCD with another model and it shouldn't cause long-term issue.            I've been replacing panels by random eBay or "local Craigslist" ones, or swapping from              other laptops for a long time, and if it works then there's no reason for it to fail because it's           not the original one.

      Now about compatibility, there are a lot of parameters to look for:
      — Dimensions: obviously if you want it to fit correctly you have to chose the same diagonal        size, this is often given directly in the model number (eg. LTN156AT32 is a 15.6" LCD). But        you also have to look at the actual outer height and width for it to fit perfectly (it's rare but            sometimes you have a few mm difference and it won't fit). Also, in some rare cases the              thickness can matter too.

       — Mountings: if it's a "slim" panel (no metal case all around the panel, circuit board on the         bottom protected by black tape), you can have a variety of mounting tabs (none at all, on           the side, top/bottom…). If it's a "standard" panel (with metal case all around), you either             screw the hinges directly or there are screwable tabs, the screw position should be the               same on all panels.

       — Protocol: LVDS or eDP (even older panels used TMDS or a custom protocol).

       — Channels: 1, 2, 4 channels… linked to the definition, the higher the definition the higher         the number of channels required. A 1-channel panel on a 2-channel motherboard should             work, but not the opposite. With LVDS, if you use 2-channels panel on 1-channel board,             typically the odd columns will be gray. Sometimes you can swap a 1-channel panel to a 2-           channel panel (to get higher definition) because the laptop is actually designed to take the         2 definition. The 2nd channel needs to be enabled and routed to the LVDS connector, and           the cable has to have the required wires (some rare laptops have 2 different cables for the         2 different definitions available).
       Higher number of channels may also mean connector with more pins.

       — Bit depth: 6-bit (262k colors) or 8-bit (16.7M colors), rarely matters, on laptops you can           typically exchange between the 2. It's relevant on desktop monitors where the panel                   configuration is programmed statically in the scaler, if you use the wrong type you'll have             scrambled image.

        — Connector type: there are 2 kinds of connector for LVDS, one with large pitch and one            with small pitch with a large latch going all over the connector, typically large pitch is found          on CCFL backlight and small pitch on LED backlight. eDP only has one kind as far as I                know, similar to the small pitch for LVDS. There are 30 and 40 pins connector (some 20              and 50 pins exist too).

         — Connector pinout: pinout is standard, if you match the protocol and the connector type          you should have the same pinout. One exception though, the large pitch LVDS on desktop          panels has the pinout reversed compared to laptop panels, if you pick the wrong one                  (desktop panels usually don't fit in laptop but you never know) you can indeed fry the                  board.

         — Connector placement: typically CCFL panels have the connector on top and LED                   panels have the connector on the bottom. Horizontal positioning can vary so always                   compare with a picture. Some laptops that are sold with different panel have different                 cables depending on the connector position.

         — Backlight:
         CCFL: not used anymore on 2009+ laptops, some desktop monitors used it for a bit                     longer. Typically the connector is always the same on laptop, on desktop monitors you               have a 2 pins (same as on laptop) and a 3 pins (middle pin is not connected). You can                 also have more than one tube on larger panels.
         LED: with integrated backlight driver or external backlight driver. Most laptops use panel             with integrated backlight driver, they send the 19V directly to the display. Most desktops             have the backlight driver on the mainboard or the power supply board.
         None: sometimes you can have panel without the backlight assembly, very rare though.             Or OLED, haven't seen one yet so cannot tell you the difference.

          — Panel orientation: this is a bit of an odd one and never seen it on laptop, but I had the           case of a desktop panel that was addressed "upside-down". No way to know it                             beforehand, and the original panel was not available, so I rotated the display in Windows,           not very good as BIOS was still showing upside-down…

         — EDID whitelist: some rare laptops may have a whitelist for panels. Seen that only on a           couple of older ones with LVDS, in that case you have to use a panel with very close                   characteristics (definition, bit depth, refresh rate) and swap (or flash) the EDID ROM chip;           it's a 24-series I2C ROM.
         While it's not a whitelist, some machines may have the EDID panel configuration statically           defined in the BIOS, in that case you also have to use a panel with very close                             characteristics. It's very rare on laptops, I think some Chromebooks with Coreboot did it…           On desktop monitors it's commonly the case as I said earlier, the panel configuration is in           the scaler firmware on the mainboard.

         There are certain combination of parameters that are extremely common, the 15.6" LVDS            panel with LED backlight (integrated backlight driver), 1366x768 definition, "standard"                  shape (non-slim), connector on bottom left… This is typically used on your low to mid-                range 15" consumer laptop from Acer, Toshiba, HP… 2008 to 2014 or something like                  that.  So yeah, those are easy to find and won't cause much trouble, there are loads of                different models that are compatible.

           And now, Apple: as expected, most of this doesn't apply with Apple panels. You have to               use the original panel on Macbooks. Connector and pinout can be proprietary, they use               a backlight driver on the mainboard rather than on the panel, panel shape and                             dimensions aren't like other laptops, they have an EDID whitelist, and you can't even                   use a 2013/2014 Retina panel on a 2015 Retina even though they have the same                       characteristics because they decided that backlight should be controlled a bit                               differently… Same for newer iMac. On old iMac like 2006 models you could swap the                 panel but it was a bit involving: there is an EDID whitelist so you have to swap the ROM,             they used a desktop panel for the 17" iMac so pinout is reversed, it's thicker and has                   special mountings, and it has 2 CCFL tubes (laptops 17" panels have only one) so you               have to connect a dummy tube behind the panel.

           Touch panels are another beast, and I haven't had to replace a fused panel yet but if you             do, you have to use the original panel as well (since the digitizer is pretty much                           designed for a specific model). For non-fused panel (where you can separate LCD from             digitizer) then you can use another model if it fits properly."  


On Sat, Nov 2, 2019 at 8:56 PM tom r lopes <tomrlopes@gmail.com> wrote:
So actually I'll be at Blue Door tomorrow 11am to 2pm.  

Not sure what I'll be doing Pi related.  

Have a thought to try to make some lcd screens work with a 
generic lvds to hdmi controller board.  Nobody wanted those Eeepc 
laptops so I just took all the parts out.  So I have 3 - 10in lcds.  What 
to do?  I already took one of the webcams and soldered to a USB 
cable.  Now I got a really small USB cam.   

Give-away is a Samsung T240HD  
Specs and pics here https://www.amazon.com/Samsung-Touch-T240HD-24-Inch-Monitor/dp/B001AYGDCE  It is very thick compared to a modern TV.  But it's free.  

Quirks:  no physical on/off button -- there is a capacitive switch on the front and 
I have a remote (somewhere -- I'll look around for it) 
No vesa mount holes on the back -- I have some where a wall mount bracket 
but that is only tilt up down.  

If interested let me know and I'll bring it this time or next week.  


P.S. Next Pi Day in December I want to work on a wireless weather station https://projects.raspberrypi.org/en/projects/build-your-own-weather-station  
Would like to get it running by 2020.  

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