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Forum Index : Microcontroller and PC projects : CMM2 All-In-One Case
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| HellbentHorse Regular Member  Joined: 08/07/2020 Location: AustraliaPosts: 55 |
Unfortunately most laptop screens use either a 30 pin or 40 pin ribbon cable and as far as I'm aware in either case you would need to connect the ribbon into a controller board to convert the signal to be able to hook up a VGA cable. You can't just graft the ribbon straight to a VGA connector. You can buy controller board kits though that for instance can have VGA/HDMI/DVI/RCA outputs so you can use the laptop panel with just about anything. An example for LCD to VGA: here |
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| JohnS Guru  Joined: 18/11/2011 Location: United KingdomPosts: 3669 |
A lot of the screen panels will be LVDS I expect. John |
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Womble Senior Member  Joined: 09/07/2020 Location: United KingdomPosts: 267 |
Very cool video link, food for thought. Just note (having looked into this) that if you "roll your own" you need a Teensy 2.0 or Sparkfun ProMicro with the ATMEGA32u4 microcontroller. You also need to check that the board you use has sufficient pins for the keyboard matrix. These boards are used my many of the bespoke mechanical keyboard kits availble. Great idea, personally I have been looking at doing something similar with an old Acorn Electron that my wife picked up for me in a local charity shop. I originally planned on putting a raspberry pi into it, but the CMM2 might be a better match. I already have the Freescale FRDM-KL25Z board to drive it as per this instructable. Tynemouth Software in the UK used to make a number of boards to rework old micros into usb keyboards although they were not cheap. The Electron has Futaba ML mechanical key switches which are wired in a simple matrix. A proper "lego on a tin tray" keyboard. I purchased a Cherry Compact G84-4100 Mechanical Keyboard, which I have tested and seems to work fine with my CMM2. Mine cost me £20 delivered on ebay, and there are a few listings at similar prices when I checked today.  The switches are Cherry ML which are not to everyones taste being short travel, but I already had a similar PS2 keyboard (purchased in 1998) which used to be my daily driver (until the trackball died) so I knew I liked them. I still use the PS2 board as my goto when building PC's on my workbench, so I know they are durable. Added bonus the G84-4100 looks great alongside my CMM2  For reference I am typing this on a Zalman ZM-K500 which has switches from Kailh and are low activation force linear non clicky switches designed as an equivalent to Cherry reds. To be honest I prefer the Cherry ML's for typing. The Zalman came free from a PC rebuild job, so the price was right, but I would not recommend it for serious typing and I have not tried it with the CMM2 as it lacks an easily accessible \ key (to get that character I need to use an undocumented AltGR+# key combo). Its fine as a cheap "ten keyless" gaming keyboard but not much use for serious work. Regards Womble |
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| djwildstar Newbie  Joined: 29/07/2020 Location: United StatesPosts: 24 |
@Womble -- Thanks for the keyboard report! The Cherry G84-4100 looks like it is exactly the same dimensions as the small laptop-style keyboard I used for my case build. Here in the US, Cherry is charging $75-$100 (the equivalent of about £60-£80) for the version with the American keyboard layout. Knowing it works and will almost certainly fit the case, I might give it a try anyway. |
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| Womble Senior Member Joined: 09/07/2020 Location: United KingdomPosts: 267 |
WARNING ... READ THIS FIRST EDIT: Peter has fixed this here. Keyboard works although no status LED's. Firmware Update Required I have done some further testing with this keyboard. In my original post (which I cannot edit) I said: I have discovered today that is not quite true !!!! pm sent to djwildstar  The clue is that the indicator LED's do not work. I am so used to having NumLock turned off in the bios on my PC's that my daily driver keyboards by default do not display any status lights. My Bad  Whilst using the G84-4100 today I accidentally hit the CapsLock key and everything stopped. That started me down a thorough testing route, and much head scratching ... Basically if you hit any of the CapsLock, NumLock or ScrollLock keys, and only those keys, the keyboard locks up and stops sending characters to the CMM2. Programs running on the CMM2 carry on running, just will not register ANY keypresses. The fix is to disconnect the keyboard at the USB-A plug and reconnect it, and everything magically starts working again.  I can only assume there is something in the keyboard that knocks it over. I opened up mine to look inside and see if I could disconnect the LED's but they are part of the key matrix pcb. I am considering wiring in a "push to break" in the keyboard 5v wire, but have not been brave enough to do that (yet). The usb keyboard controller is separate from the keyswitch pcb (connected by a soldered ribbon cable) and the usb cable is connected with a plug so can be shortened for use inside a custom case. Apart from this GOTCHA the keyboard does do keyboardy things. I really like the "feel" of the Cherry ML key switches, and I intend to continue using it with my CMM2 for the time being. Can I recommend the keyboard ... probably NO but it does work (sort of). Edit: Now Fixed  , so YES, this is now my preferred keyboard for the CMM2As part of my testing I aslso tried the keyboard on my Windows pc, and there it performed faultlessley. The indicator leds work, and all the keys function as they should. One to look out for second hand or for cheap ... but do not pay full price!!! I do not know if this is peculiar to the Cherry G84-4100, or if other Cherry keyboards do this. It might be because this board will work with the supplied PS2 adapter. YMMV. Regards Womble EDIT: Peter has fixed this here. Keyboard works although no status LED's. Firmware Update Required Edited 2020-09-21 23:39 by Womble |
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