From 8a9bf1f1653a5029ffd8f1e1171cd0b16bc2bc71 Mon Sep 17 00:00:00 2001 From: Gergely Nagy Date: Sat, 30 Jul 2016 08:37:30 +0200 Subject: Update some obsolete references Some links were still pointing to `/keyboards/ergodox_ez`, while the directory is `/keyboards/erdogox` now. Not all references have been updated, and some of the text here and there may need updating to mention the ErgoDox Infinity too, but that's out of the scope for this quick fix. Signed-off-by: Gergely Nagy --- doc/TMK_README.md | 2 +- doc/VAGRANT_GUIDE.md | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'doc') diff --git a/doc/TMK_README.md b/doc/TMK_README.md index 6164dacd3..f3d96717a 100644 --- a/doc/TMK_README.md +++ b/doc/TMK_README.md @@ -34,7 +34,7 @@ You can find some keyboard specific projects under `converter` and `keyboard` di * [atomic](keyboards/atomic/) - [Atomic] Ortholinear 60% keyboard ### Ergodox EZ -* [ergodox_ez](keyboards/ergodox_ez) - [Ergodox_EZ] Assembled split keyboard +* [ergodox_ez](keyboards/ergodox/ez) - [Ergodox_EZ] Assembled split keyboard ## Other projects diff --git a/doc/VAGRANT_GUIDE.md b/doc/VAGRANT_GUIDE.md index 62044b7f7..c9958e16b 100644 --- a/doc/VAGRANT_GUIDE.md +++ b/doc/VAGRANT_GUIDE.md @@ -20,7 +20,7 @@ See [/doc/keymap.md](/doc/keymap.md). ## Flashing the firmware -The "easy" way to flash the firmware is using a tool from your host OS like the Teensy programming app. [ErgoDox EZ](/keyboards/ergodox_ez/readme.md) gives a great example. +The "easy" way to flash the firmware is using a tool from your host OS like the Teensy programming app. [ErgoDox EZ](/keyboards/ergodox/readme.md) gives a great example. If you want to program via the command line you can uncomment the ['modifyvm'] lines in the Vagrantfile to enable the USB passthrough into Linux and then program using the command line tools like dfu-util/dfu-programmer or you can install the Teensy CLI version. - \ No newline at end of file + -- cgit v1.2.3 From d9bef1658e062d76f87a752daa30047d865dca0f Mon Sep 17 00:00:00 2001 From: Jiehong Ma Date: Sun, 31 Jul 2016 16:49:31 +0200 Subject: feature: add basic doc about how a keyboard works on USB This comes from the discussion on #520 --- doc/basic_how_keyboards_work.md | 96 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 doc/basic_how_keyboards_work.md (limited to 'doc') diff --git a/doc/basic_how_keyboards_work.md b/doc/basic_how_keyboards_work.md new file mode 100644 index 000000000..73c3f5c5f --- /dev/null +++ b/doc/basic_how_keyboards_work.md @@ -0,0 +1,96 @@ +# How keys are registered, and interpreted by computers + +In this file, you can will learn the concepts of how keyboards work over USB, +and you'll be able to better understand what you can expect from changing your +firmware directly. + +## Schematic view + +Whenever you type on 1 particular key, here is the chain of actions taking +place: + +``` text ++------+ +-----+ +----------+ +----------+ +----+ +| User |-------->| Key |------>| Firmware |----->| USB wire |---->| OS | ++------+ +-----+ +----------+ +----------+ |----+ +``` + +This scheme is a very simple view of what's going on, and more details follow +in the next sections. + +## 1. You Press a Key + +Whenever you press a key, the firmware of your keyboard can register this event. +It can register when the key is pressed, held and released. + +This usually happens with a [periodic scan of key presses with a frequency around 100 hz](https://github.com/benblazak/ergodox-firmware/blob/master/references.md#typical-keyboard-information). +This speed often is limited by the mechanical key response time, the protocol +to transfer those key presses (here USB HID), and by the software it is used in. + +## 2. What the Firmware Sends + +The [HID specification](http://www.usb.org/developers/hidpage/Hut1_12v2.pdf) +tells what a keyboard can actually send through USB to have a chance to be +properly recognised. This includes a pre-defined list of keycodes which are +simple numbers from `0x00` to `0xE7`. The firmware assigns a keycode to each +key of the keyboard. + +The firmware does not send actually letters or characters, but only keycodes. +Thus, by modifying the firmware, you only can modify what keycode is sent over +USB for a given key. + +## 3. What the Operating System Does + +Once the keycode reaches the operating system, a piece of software has to have +it match an actual character thanks to a keyboard layout. For example, if your +layout is set to QWERTY, a sample of the matching table is as follow: + +``` text +| keycode | character | +|---------+-----------| +| 0x04 | a/A | +| 0x05 | b/B | +| 0x06 | c/C | +| ... | ... | +| 0x1C | y/Y | +| 0x1D | z/Z | +| ... | ... | +|---------+-----------| +``` + +## Back to the firmware + +As the layout is generally fixed (unless you create your own), the firmware can +actually call a keycode by its layout name directly to ease things for you. + +This is exactly what is done here with `KC_A` actually representing `0x04` in +QWERTY. The full list can be found in `keycode.txt`. + +## List of Characters You Can Send + +Putting aside shortcuts, having a limited set of keycodes mapped to a limited +layout means that **the list of characters you can assign to a given key only +is the ones present in the layout**. + +For example, this means that if you have a QWERTY US layout, and you want to +assign 1 key to produce `€` (euro currency symbol), you are unable to do so, +because the QWERTY US layout does not have such mapping. You could fix that by +using a QWERTY UK layout, or a QWERTY US International. + +You may wonder why a keyboard layout containing all of Unicode is not devised +then? The limited number of keycode available through USB simply disallow such +a thing. + +## How to (Maybe) Enter Unicode Characters + +You can have the firmware send *sequences of keys* to use the [software Unicode +Input +Method](https://en.wikipedia.org/wiki/Unicode_input#Hexadecimal_code_input) of +the target operating system, thus effectively entering characters independently +of the layout defined in the OS. + +Yet, it does come with multiple disadvantages: + + - Tied to a specific OS a a time (need recompilation when changing OS); + - Within a given OS, does not work in all software; + - Limited to a subset of Unicode on some systems. -- cgit v1.2.3