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Forum Index : Microcontroller and PC projects : PicoMite VGA Keyboard
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palcal Guru  Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Up until now I have been using my Picomite VGA through a terminal because I was waiting on the PS2 socket. Got the socket but found I no longer had a PS2 keyboard, you know, the big cleanup, I'll never need these again. I am using a USB keyboard with a USB to PS2 adaptor, but the keyboard does not work. Before I go looking for a fault this keyboard should work with the adaptor, yes or no. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| al18 Senior Member  Joined: 06/07/2019 Location: United StatesPosts: 174 |
Does the keyboard light blink or remain on? |
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bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
Hi PalCal, Assuming your KB is PS2 `compatible' I believe there are 2 types of USB-PS2 converters A GREEN one for a Mouse and a less common PURPLE one for Keyboards I `think' they are wired to different pins on the PS2 side. This might be your problem but as with many things these days, I may be TOTALLY WRONG. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Thanks for that, I checked and have power to the KB socket but no lights on KB. I'll see if I can dig up a PS2 KB. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Apparently from what I have read, newer PS2 KBs use the USB wiring convention. So I will have to be careful if I buy a new KB. If I get a PS2 plug I should be able to wire it onto the USB KB. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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Rickard5 Guru Joined: 31/03/2022 Location: United StatesPosts: 328 |
Not all USB KB Encoders are 3.3 Volt tolerant, Like my beloved IBM Model M PS/2 Keyboards Hate Picos, because of the power issue. I been using these sometimes they go on-sale for $3 and work with the Green usb-ps2 adapter, and they use to have a PS/2 Version you could do the reverse and go PS/2 to USB, I keep one in the car at all times, never know when you got to work on legacy Junk like Novel servers I built in the 90's (Yes some one just just got $$$$ hit hard to upgrade their Netware 3.11 server to NAS) ;) :) :) Edited 2022-05-12 15:22 by Rickard5 I turned the volume on the monitor to max and could hear sound. Thanks Stanleyella |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5713 |
The actual sockets for PS/2 only vary in colour. The socket pins in all of them are identical AFAIK. You can get green, purple and black to my knowledge. I think I've seen grey too. If a USB keyboard isn't working (with something that's known to work with a PS/2 keyboard) via an adapter then there's usually one of two problems: 1) It's not designed to. Not all USB keyboards can handle the PS/2 protocol, no matter how you connect them. 2) It would do, but you are using a 5V only keyboard on a 3V3 system. This is a common problem with USB keyboards, which never expect a 3V3 supply. Some PS/2 keyboards are 5V only and won't work on a 3V3 system. Always better to include a 5V keyboard supply and level shifters. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
The PS2 socket on the Pico VGA is 5 volt it connects to Vsys. It has got me stumped. The keyboard lights up when connected to my computer. I checked the USB side of the adaptor and have 5 volts on pins 1 and 4, I plug in the keyboard and no go, the same with 2 keyboards that work on my computer. Thinking the USB side of the adaptor has a pin not connecting I plugged in a USB extension cable and have 5 volts on the female end, I plug the keyboard into the extension cable, no go. ???? "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5713 |
Odd... If it's Peter's version 1.3 VGA board then a few people are using it now. Have you got the mosfet level shifters in right way round? Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| al18 Senior Member Joined: 06/07/2019 Location: United StatesPosts: 174 |
I don’t think there are any newer PS/2 keyboards - this is an obsolete standard that was dropped years ago. I recently picked-up a nice used Compaq PS/2 keyboard at the Goodwill. Store for $5 that works fine. The sticker on the bottom says 5v 50 mA - so it doesn’t use much power. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Mosfets I used are 2N7000 and have fitted them in opposite to the layout as they should be. I'm using a board that Turbo46 kindly gave me, he used the 2N7000s The thing is if I have 5 volts to the KB it should light up, shouldn't it ? Edited 2022-05-12 18:27 by palcal "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1779 |
"I don’t think there are any newer PS/2 keyboards - " Early in the PicoMite and ArmMiteF4 development it was discovered that new Microsoft basic model keyboards are still PS/2 compatible (and will work down to 3V and don't need pullup resistors). Search there for the model number. Had a go but no luck. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Well I have checked the voltage around the level shifters and traced every connection, but I can't find a fault. I've tried 3 known good KBs and none work. As a last resort I will grab a 6 pin mini din connector when I'm in town on Saturday and put it on the keyboard instead of the USB plug and if that doesn't work I just don't know. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5898 |
Do you KNOW that the keyboards are PS/2 capable? Not many current ones are. Jim VK7JH MMedit  MMBasic Help |
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| al18 Senior Member Joined: 06/07/2019 Location: United StatesPosts: 174 |
Jim has a point. Ps/2 keyboards are quite different from USB keyboards. Your USB to PS/2 adapter does NOT contain a CPU to convert the signals - this is handled by the CPU inside your keyboard. FYI the used Compaq KB-0133 PS/2 keyboard I bought recently is in very good condition. I See they are still being sold on eBay for around $12 if you can’t find them locally. Edited 2022-05-13 09:41 by al18 |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1779 |
To check the operation of the level shifters, with KB un-plugged measure the voltages on clock and data pins on the socket. Should be about 5V. Repeat for the Pico pins. Should be about 3V3. Now link the clock and data pins on the socket to ground. The Pico pins should now be 0V. Repeat grounding the Pico pins and measuring the socket pins. Trace the PCB tracks to be certain I/O pin GP8 goes to clock and GP9 to data on the socket. The next thing is to try swapping the clock and data connections to the socket and see if the keyboard works now. Tricky to do on a PCB, perhaps remove the socket and run wires back to the pads. If none of that helps I guess the keyboards just don't do PS/2. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Probably the KBs I'm using, I also have some old Honeywell KBs with 5 pin DIN socket, I can get an adaptor for those at Jaycar. These KBs have the AT/XT switch on the bottom. Would they be suitable. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5898 |
Perfect. You need the switch in the 'AT' position. VK7JH MMedit  MMBasic Help |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1798 |
Thanks all, I can't get an adaptor locally but I can change the plug to Mini DIN. When this VGA PicoMite appears in Silicon Chip and if it goes well where is everyone going to get PS2 Keyboards. Second hand on EBay there are some but no new ones around. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| al18 Senior Member Joined: 06/07/2019 Location: United StatesPosts: 174 |
That’s a good question. I would like to know if attaching a USB keyboard thru a USB on the go cable is possible. I searched the web and there are some Pico projects this implemented. |
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