Looking for a PS/2 to USB IC for keyboard - Page 1
Forum section: electronics / projects

author: 8086
author_rank: Super Contributor
timestamp: July 18, 2012, 12:20:24 am
content: All I have found so far is the SH3301 but it's obsolete and nowhere has it in stock.http://www.digchip.com/datasheets/parts/datasheet/420/SH3301.phpAnyone know of any alternatives?cheers

author: digsys
author_rank: Unknown
timestamp: July 18, 2012, 01:44:31 am
content: QuoteI use a common CP210x USB to UART bridge (+IO) first, then tie another small CPU to it andwrite a SPI (PS2) decoder. The PS2 waveforms are pretty simple to create. I use the Silicon labs bridge -www.silabs.com/products/interface/usbtouart/Pages/usb-to-uart-bridge.aspxbut there are others around. These are quite "new" devices, so they'll be around a while.IF you didn't want to add a CPU, you could easily BIT BASH a PS2 (SPI) waveform.

author: 8086
author_rank: Super Contributor
timestamp: July 18, 2012, 02:25:32 am
content: Thanks, but from the sound of it you have my problem backwards. I want to have ps/2 input and USB output...which is the reverse of the norm really.

author: digsys
author_rank: Unknown
timestamp: July 18, 2012, 06:29:29 am
content: Quote from: 8086 on July 18, 2012, 02:25:32 amMaybe I mis-interpreted it, PS2 to USB adapters (quite small) were very common and should be easy to find.IF you just want the chip, open one up (or two), they're cheap.The USB bridge will still work though -You have a PS2 socket on the PCB, decode it to ANSII or whatever format M/Soft requires, then spit it outthe USB port. The CP210x come with royalty free drivers. All you'd need to do is "match" the USB to a KeyboardInput "socket". Been a while since I've done that, so I'd need to look it up again.

author: amyk
author_rank: Super Contributor
timestamp: July 18, 2012, 10:35:14 am
content: I think the confusion here is the use of the terms "input" and "output".He wants a converter that can connect a PS/2 keyboard to a USB host.

author: d15ea5e
author_rank: Newbie
timestamp: July 18, 2012, 10:45:16 am
content: Maybe you try to do it the software way? PS/2 protocol if fairly simple (especially if you want to implement keyboard->host transfer only). Any 8bit uC can do it. Next you can use any uC with built-in USB transceiver or if you use AVR - there is V-USB - software implementation of USB1.0 (free for noncommercial use).

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 18, 2012, 12:54:39 pm
content: Quote from: 8086 on July 18, 2012, 02:25:32 amReverse of which norm? No such thing as USB to PS/2 exists, only passive plug adapters, but protocol is handled in the keyboard controller.But why bother for an IC when you can get PS2 to USB dongles for a couple of dollars on Ebay?Btw. not worthwhile getting those to extract the ICs, looked at two of these adapters here, and both use a die-on-board.Depending on acceptable risk, required quantity and long term requirement, you can try posting a buy request for the obsolete part onhttp://www.hkinventory.com/public/Home.asp.Usually not much of a problem for non-high-risk components.

author: 8086
author_rank: Super Contributor
timestamp: July 18, 2012, 02:08:34 pm
content: Quote from: amyk on July 18, 2012, 10:35:14 amcorrect.Quote from: Short Circuit on July 18, 2012, 12:54:39 pmBy reverse of the norm I mean mostly you find the adaptors you mentioned for converting USB keyboards to ps/2 host, and not really much (that works, according to amazon reviews) the other way around.I want an IC so I can integrate it into something nicely, don't really want to have a dongle attached.If the protocol is handled in the keyboard for USB -> ps/2, then does this mean that the keyboard is reconfiguring the usb connection to provide the ps/2 signals and repurposing the usb lines for this? If there's clk and dat plus 5v and gnd how does it know that it needs to enter this mode of operation? If it's not enumerating with a usb host is this a default state?

author: amvakar
author_rank: Contributor
timestamp: July 18, 2012, 03:05:41 pm
content: http://www.sprintek.com/products/SK5100.aspxwould seem to do what you want, provided you ignore the matrix and LED functionality.

author: SeanB
author_rank: Super Contributor
timestamp: July 18, 2012, 03:08:35 pm
content: Those adaptors are nothing but a green blob with the wires to connect each side to the other. they have the keyboard ( or mouse) controller look to see if the USB host tries to enumerate after power on, and then it chooses USB mode. If there is no enumeration attempt then it defaults to PS2 mode and uses the clock and data line like a normal PC. I have had a few around with older Microsoft V1.1 intellimice.

author: Distortion
author_rank: Newbie
timestamp: August 19, 2014, 11:50:19 pm
content: Was looking for the same solution online and found that topic. Then i've found this:http://ww1.microchip.com/downloads/en/AppNotes/91055C.pdfhttp://ww1.microchip.com/downloads/en/AppNotes/91058C.pdfhttp://ww1.microchip.com/downloads/cn/AppNotes/cn_91056C.pdf

author: macboy
author_rank: Super Contributor
timestamp: August 20, 2014, 02:57:14 pm
content: Quote from: SeanB on July 18, 2012, 03:08:35 pmThat is usually the case when the adapter comes with a peripheral, especially mice. However, the adapters that are sold separately are truly active, with PS/2 on one side and USB on the other. This is especially true when it is a USB host to PS/2 peripheral adapter.

author: masstechminer
author_rank: Newbie
timestamp: June 21, 2020, 06:32:15 pm
content: This is quite an old topic, but it is still the #1 result on google if you search PS2 to USB ic, so I figured it would be work putting what I found in here. You can use the WIT122 IC, it is purchasable for around a dollar in small quantities from sites such as aliexpress.com, and use the below schematic to run it.

author: shmueld
author_rank: Newbie
timestamp: July 04, 2021, 01:37:23 pm
content: I am looking for a similar solution i.e. USB to PS/2 converter - using some sort of IC.masstechminer,Have you actually used this chip ? Is there some sort of data sheet for it - I couldn't find it anywhere ? I also couldn't find any info on the Co. and question the reliability of such a chip ?Distortion,Have you implemented this MicroChip solution ? These solutions are using very old chips ?!Has anyone else got any other suggestions ?

author: Bassman59
author_rank: Super Contributor
timestamp: July 04, 2021, 11:22:39 pm
content: Quote from: shmueld on July 04, 2021, 01:37:23 pmI interpret this question as "I have a thing which presents a PS/2 port for use with a keyboard and mouse and I want to connect a modern (USB) keyboard and mouse to it."Is this correct?If so, my guess is you're gonna be outta luck. I guess that "thing" is an ancient computer? Maybe scour eBay or the like looking for old PS/2 keyboards or mice?Another solution is the use a microcontroller with a USB Host interface to talk to the keyboard and mouse, and have that micro translate mouse and keyboard events into PS/2 messages. The microcontroller vendors who sell parts with USB Host interfaces have good examples of how to talk to keyboards and mice.

author: Benta
author_rank: Super Contributor
timestamp: July 05, 2021, 08:25:25 am
content: There are two answers to this, depending on the direction you want to go:1: USB keyboard to PS/2 PC: Easy, a passive adapter will do it provided the keyboard supports USB signalling. A dollar perhaps?2: PS/2 keyboard to USB PC: you need an active adapter, they cost around 10...12 US$.

author: Bassman59
author_rank: Super Contributor
timestamp: July 05, 2021, 08:38:57 pm
content: Quote from: Benta on July 05, 2021, 08:25:25 amThe keyboard has to support PS/2 signaling. The old passive green things worked because the mouse or keyboard could do both PS/2 and USB, but I doubt that anything made in the last dozen years supports such.

author: llkiwi2006
author_rank: Regular Contributor
timestamp: July 05, 2021, 08:56:06 pm
content: You can use this firmware for ATmega32u4. Allows you to define a custom keymap too.https://geekhack.org/index.php?topic=103648.0

author: Fraser
author_rank: Super Contributor
timestamp: July 08, 2021, 12:36:47 pm
content: I own a rugged arm mounted military type keyboard that uses PS2 and wanted to connect it to a USB port.Many PS2 to USB adapters have a reputation for working with some hosts but not others. Some have intermittent connection and are unreliable.The best adapter to be found was the Blue Cube. I found a used one and this adapter has an excellent reputation. Worth seeking outhttps://www.reddit.com/r/MechanicalKeyboards/comments/kpzxk7/possible_blue_cube_successor_in_the_sanoxy_ps2_to/

author: Fraser
author_rank: Super Contributor
timestamp: July 08, 2021, 01:15:22 pm
content: The Sanoxy adapter also seems to work.A conversion job from PS2 to USB is detailed here….http://www.catb.org/esr/trackman-conversion/

author: Benta
author_rank: Super Contributor
timestamp: July 08, 2021, 05:05:04 pm
content: I use a couple of SYBA adapters for my original Model M keyboards. Works 100%.https://www.sybausa.com/index.php?route=product/product&product_id=681