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Forum Index : Microcontroller and PC projects : USB Keyboard - slow response/dropped keypresses
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10223 |
Can you download again please - I updated the download in the last few muinutes |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 617 |
Of course, give me a second, I'll try it again with all keyboards!  |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2434 |
Peter, see: https://www.usb.org/sites/default/files/documents/hid1_11.pdf Universal Serial Bus (USB) Device Class Definition for Human Interface Devices (HID) Firmware Specification—6/27/01 page 62 (72/97 in PDF) reads: "The keyboard must report a phantom state indexing Usage(ErrorRollOver) in all array fields whenever the number of keys pressed exceeds the Report Count. The limit is six non-modifier keys when using the keyboard descriptor in Appendix B. Additionally, a keyboard may report the phantom condition when an invalid or unrecognizable combination of keys is pressed." page 74 (84/97 in PDF) reads: "- The Boot Keyboard shall report “Keyboard ErrorRollOver” in all array fields when the number of non-modifier keys pressed exceeds the Report Count. The limit is six non-modifier keys for a Boot Keyboard. - The Boot Keyboard shall report “Keyboard ErrorRollOver” in all array fields when combination of keys pressed cannot be accurately determined by the device, such as ghost key or rollover errors." the value for ErrorRollOver can be found in: https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf Universal Serial Bus (USB) HID Usage Tables 10/28/2004 Version 1.12 on page 53 (53/168 in PDF), table 12: Table 12: Keyboard/Keypad Page Usage ID Usage ID Usage Name Position PC-AT Mac UNIX Boot (Dec) (Hex) 0 00 Reserved (no event indicated) N/A √ √ √ 84/101/104 1 01 Keyboard ErrorRollOver N/A √ √ √ 84/101/104 2 02 Keyboard POSTFail N/A √ √ √ 84/101/104 3 03 Keyboard ErrorUndefined N/A √ √ √ 84/101/104 4 04 Keyboard a and A 31 √ √ √ 84/101/104 5 05 Keyboard b and B 50 √ √ √ 84/101/104 6 06 Keyboard c and C 48 √ √ √ 84/101/104 [...] ie, 0x01 in each of the 6 array positions: "010101010101". hopefully this should help. cheers, rob :-) addendum: if my reading of the documentations is right, there is NO order to the 6 slots. it is up to the host to figure out the order of keypresses by comparing one report to the next. see page 72 from the first PDF: "The order of keycodes in array fields has no significance. Order determination is done by the host software comparing the contents of the previous report to the current report. If two or more keys are reported in one report, their order is indeterminate. Keyboards may buffer events that would have otherwise resulted in multiple event in a single report." Edited 2025-07-08 00:36 by robert.rozee |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 617 |
Same problem, but to be sure I generated the MD5 checksum, so that you can compare the version: Md5 Checksum online tool: https://emn178.github.io/online-tools/md5_checksum.html It gives me "3971224a263653cd6881573a34df4d7a" for your file. Here sadly the same problems, new image:  |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10223 |
Please just run a single finger across vbnm as fast as possible - what happens? |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10223 |
This means if the first time two keys appear is in the same report there is no way the software can determine their order - what a crap I/F! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2434 |
it is up to the host to poll the USB keyboard every 1ms and compare the previous report to the current one. from there the host builds up a map of what keys it believes are down and what are up. when the host sees the "010101010101" report it then (presumably) is expected to throw out the map it has previously built up and start afresh. cheers, rob :-) Edited 2025-07-08 00:53 by robert.rozee |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 617 |
Ok done. With a single finger I wasn't able to produce any false chars or missing or swapped chars. Then I tried to write in my maximum speed in german and english (a bit slower), here I can't replicate any of the mentioned "problems". It only appears if there is rollover involved. And this (rollover?) problem with the group of "VBNM" starts really quickly, I must not type fast that the problem occurs. But what (for me counts) I wasn't able to re-create any of the mentioned problems with normal writing. Before your fixes, I wasn't able to write the word "save" for example. Now with an english text and some keywords I tested, the problem isn't re-producable under normal circumstances. So for me, as said a few post ago, absolutly usable now. Although the problems persist under the mentioned circumstances, I think we have to live with that - which is fine because: only a few people have those problems and as it is now with the fixes, it is even for me highly unlikely that I run into problems again. So I think further fixes will be just for sports (is it even called this way in english?)  Edited 2025-07-08 01:00 by Amnesie |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10223 |
That doesn't work because as we have proved in an earlier test version it creates duplicates as a key can appear both before and after the error code. Even with a 1mSec scan it is perfectly possible for two keys to be pressed and the order in the array ought to indicate their order but again, the evidence from the difference between Amnesie's keyboards and mine is that they seem to report in the opposite order. Currently it seems like the last version last night is the best with the only issue that after a 0x010101010101 Amnesie sees a swapped pair of characters. I don't. |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 617 |
I have no clue about all of this, but I think the same. That is the best version. To sum up: - You fixed the missing chars (this was the worst problem!) - the dublicate chars (was a bad problem, too) Now there are still swapped chars and when typed really really fast with rollover there is a missing char again (latest firmware ONYL) So yes, last night version was the best, under normal circumstances I see no way of having any problems with it. Edited 2025-07-08 01:11 by Amnesie |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2434 |
if two keys are pressed down in the time interval between reports (ie, both within a 1ms period) then who is to say that one was pressed before the other? the clue is in the "H" of HID: human. a human can not determine the order of two events that occur within 1ms of each other, hence the time-ordering is irrelevant for any practical human-machine interface. cheers, rob :-) Edited 2025-07-08 01:11 by robert.rozee |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 617 |
I have no clue about all of this, but I think the same (only from testing). This is the best version. To sum up: - You fixed the missing chars (this was the worst problem!) - the dublicate chars (was a bad problem, too) Now there are still swapped chars and when typed really really fast with rollover there is a missing char again (latest firmware ONYL) So yes, last night version was the best, under normal circumstances I see no way of having any problems with it. My whole summary is: PS/2 is such a great thing for it's simplicity .. but I understand, we can not live in the past forever Edited 2025-07-08 02:11 by Amnesie |
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