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Forum Index : Microcontroller and PC projects : Keyboard
| Author | Message | ||||
Juri74 Senior Member  Joined: 06/02/2012 Location: ItalyPosts: 162 |
recently i've had a lot of problems with my old ps2 keyboard so i decided to switch to a new one.. problem is that it's almost impossible to find a brand new ps2 keyboard.. so i take one of those usb keyboard + ps2 adaptor.. problem is that when i connect to maximite or duinomite a repeated "v" appear on screen it seems one "v" every half second, i tried 3 different keyboard but result was the same (vvvvvvvvvvv....) anyone could please address me to a working usb keyboard please? thank you very much Juri |
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| ronee Newbie  Joined: 08/01/2012 Location: CanadaPosts: 20 |
Hi Juri, Yes, I had the same problem. I never solved it, so glad to hear this being discussed Ron |
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BobD Guru  Joined: 07/12/2011 Location: AustraliaPosts: 935 |
I have a Logitech Ultra Flat usb keyboard (5 volts 100mA) with a Logitech usb to PS2 adapter and it works OK. Only trouble is it crowds the VGA connector and I had to trim that one to allow them both to fit and I have to plug the VGA in first. Check your keyboard's power consumption. USB2 was allowed to output 500mA and if a keyboard used anywhere near that then it may cause troubles with the MM power supply. I have some other keyboards (all usb) and adapters here somewhere. I'll see if I can find them and try them. This looks like my keyboard although mine is several years old. Logitech Ultra Flat keyboard Experience superior typing comfort with an ultra low profile keyboard.
Adjustable keyboard height provides ergonomic comfort. Stylish design complements flat screen monitors and allows users to save space. System Requirements: Windows Vista & Windows XP/2000/98. USB & PS/2 enabled. Manufacturer's Warranty 3 Years |
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YT2095 Newbie Joined: 07/02/2012 Location: United KingdomPosts: 22 |
although I cannot be 100% sure, I have some evidence that would seem to suggest you may have a bad connection somewhere. I also experienced the "v" thingy on my monitor this morning whilst plugging in my PS2 keyboard (it`s a USB KBD with a PS2 adapter). now although only One of the "v"s apeared as i was pushing in the plug, I was able to replicate this a few times. Once the plug is fully in place it never happens again, only when it`s half in/out. now it Could be, just as the above poster said, and the act of pluging it in causes a power dip as it charges up Capacitors and encoder chip and maybe even the status leds, and then quickly settles when all reaches the correct charge. it would certainly be interesting to find what the fascination with "V" is though? I`ll have to look up the ASCII code and Binary equiv, maybe there`s something unique to that letters code that tricks the DM/MM into thinking it`s valid data? so anyway, you`re Not on your own, your findings are independently repeatable, and it looks likely to be a Power insufficiency or a bad connection. all the best ;) |
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darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
Hi , I get the 'v' when i plug in the German USB->PS2 keyboard. And never after that. Now , if this KB is connected to the MM and i power on .... no 'v' appear. When i try with a pure PS2 French KB , nothing append at all when i plug / unplug the KB. I think that it can be a communication between the PC/KB for initialisation or something like that with a USB device. As the MM just check the serial data coming out the KB then it do like as you press the 'v' at initialisation. The 'v' hardware coded from the KB is the 0x2A code ... then if someone know if this is used to initialise a USB KB we get the answer 
Cheer. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| YT2095 Newbie Joined: 07/02/2012 Location: United KingdomPosts: 22 |
0x20 when I looked it up seems to be the Shift code on a PS2 kbd, as there`s no difference for the letters Upper or Lower case unless preceeded by this shift code of 0x2a. so maybe it`s the Caps Lock led circuit? that`s why they flash during INIT. I`m just guessing here :) |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
0x20 or (32 in decimal) don't have any assignment in the MM KB map. When it's so the key-code = 0 and don't put any character out
Hardware key-code is like a maze , i will like to see the one who created this misery to give him a bottle of poison to be sure he will not try again .... he he he for info : CTRL code = 0x14 Left Shift = 0x12 Right Shift = 0x59 Caps = 0x58 etc ... etc ... But for more info you can look at the PS2 Keyboard key-code standard. The USB to PS2 adapter don't modify anything , it just put the connection to the right place without any change in the signals. As i know , for the key , USB KB use exactly the same code as PS2 because i have made allot test before the integration in the MM for the FR,GR and IT Keyboards. But something stay open in my mind , why the 'v' when i put the KB when the MM is at work and nothing when the KB is still connected at start. It can be that the PIC32 start-up take some time to stabilise the oscillator and in that time the 'v' char is dropped out from the KB ... Best solution is then to have the MM fit into the KB and I'm sure that the Gizmo stick can be put in without problems 
Cheers
Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
as I said a couple of days back, I would check my collection of keyboards. They are all usb. They all work OK in the MM with my adapter. Most of these adapters are active devices. They have electronics in them to convert from usb to keyboard signals. Some may be better than others. It may not be a keyboard fault you guys are looking at but an adapter fault. Does it work OK if it plugged in before power up? |
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| MM_Wombat Senior Member Joined: 12/12/2011 Location: AustraliaPosts: 139 |
I am using a ps2 keyboard with no usb -> ps2 gender bender. My maximite does the same thing.. I also notice that the caps lock led does not light up, even though the keyboard sends the data to the maximite as Upper Case.... I just got more ps2 keyboards from cash converters (s/hand shop) for $2 each....(My maximite was blowing them up.. [7805 was putting out 6.1 volt]) I also notice that sometimes, after I release the left cursor key( after a long press) that a '6' appears in the edited line....and a '4' when I use the Up cursor key.... Keep plugging away, it is fun learning But can be expensive (if you keep blowing things up). Maximite, ColourMaximite, MM+ |
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