232 lines
11 KiB
Markdown
232 lines
11 KiB
Markdown
keybrd Library User's Guide
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===========================
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keybrd is a library for creating custom-keyboard firmware.
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This guide shows how to:
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* set up the Arduino development environment
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* install the keybrd library
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* compile and load keybrd firmware
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The Arduino development environment is free and simple as possible.
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Its easy for novice programmers to setup and learn.
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Who this guide is for
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---------------------
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This guide is for anyone who wants to use the keybrd library to develop keyboard firmware.
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A reader with programming experience, but no C++ experience, would understand the tutorials well enough to modify existing keybrd sketches.
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An experienced C++ programmer would be able to write original sketches and classes.
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The library is written in the C++ language.
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keybrd sketches use keybrd classes, objects pointers, aggregation, and static class variables.
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Microcontroller board requirements
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----------------------------------
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The keybrd library works with Teensy and Arduino compatible boards with at least 2 KB SRAM.
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[Teensy LC](https://www.pjrc.com/teensy/teensyLC.html) is the preferred board for the keybrd library and is used in the tutorials. Teensy LC has 8 KB SRAM, which is enough memory for any keyboard.
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Getting started with Teensy, Arduino IDE, and keybrd
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----------------------------------------------------
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The Arduino IDE is used to
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1. edit sketches
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2. compile sketches into HEX files
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3. load the HEX file onto the microcontroller
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Teensyduino is a software add-on for the Arduino IDE that allows it to compile to Teensy.
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[Teensy Getting Started](http://www.pjrc.com/teensy/first_use.html) is a good way to familiarize yourself with Teensy.
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[Arduino Development Environment](http://arduino.cc/en/guide/Environment) is a brief description.
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The following steps create an Arduino development environment for keybrd sketches.
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### Install Arduino IDE and Teensyduino
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The following install steps are modified from the [Teensyduino download page](https://www.pjrc.com/teensy/td_download.html).
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For Linux:
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1. Download and extract the Arduino software to the /opt directory:
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/opt/arduino-1.x.x
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2. The "Linux udev rules" link is at top right of page.
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Save the teensy.rules file in /etc/udev/rules.d/
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3. "Teensyduino Files" installer links are at top of page.
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Download the installer to your Downloads directory.
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Make the installer executable:
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$ chmod 755 teensyduino.64bit
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Run the teensyduino installer and fill the form fields:
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Arduino location to install Teensyduino: /opt/arduino-1.x.x
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Libraries to Install: keybrd
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4. Launch Arduino IDE from /opt/arduino-1.x.x/arduino
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<!-- todo no longer needed, delete after testing Arduino library manager
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### Download and unpack keybrd-master.zip into your Arduino directory
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link from tutorial 8 ## Publishing
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https://www.arduino.cc/en/Guide/Libraries
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* Installing Additional Arduino Libraries
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* Using the Library Manager
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Down load keybrd-master.zip from the [Download ZIP](https://github.com/wolfv6/keybrd) button.
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Unpack keybrd-master.zip into your Arduino directory on your system (default location is ~/Documents/Arduino/).
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-->
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### Install keybrd extension libraries
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The keybrd library contains the foundation classes for creating a keyboard firmware.
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For emphasis, it is sometimes referred to as the "core keybrd library".
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keybrd extension libraries contain additional classes that extend the keyboard library.
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keybrd extension library names are prefixed with "keybrd_".
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Instructions for installing Arduino libraries are at: http://www.arduino.cc/en/Guide/Libraries
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The default location for Arduino libraries is ~/Documents/Arduino/libraries/.
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For example, the DodoHand keyboard requires the core keybrd library and the keybrd_DH extension library be installed.
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After installing the libraries, my Arduino directory looks like this:
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* ~/Documents/Arduino/libraries/keybrd/
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* ~/Documents/Arduino/libraries/keybrd_DH/
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### Setup Arduino IDE for compiling keybrd firmware
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From the Arduino IDE tool bar, select:
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* Tools > Board > Teensy LC (or whatever board you are using)
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* Tools > USB Type > Keyboard + Mouse + Joystick
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These are optional:
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* File > Preferences > Compiler warnings: All
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* File > Preferences > check: Use external editor
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### Compile and load keybrd sketch
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If it isn't already plugged in, plug the USB cable into the computer and controller.
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> CAUTION: It is possible to loose control of your keyboard when running a keybrd sketch.
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> If the keybrd sketch has a mouse object, it is possible to loose control of your mouse too.
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> USB keyboard protocol is capable of spewing characters and mouse commands at up to 500 per second.
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> Take the following precautions before uploading an untested keybrd sketch to a controller:
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> * Save all files and close dangerous applications.
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> * Park the cursor in an editor opened to a test file.
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> That way you can immediately see if the controller starts spewing characters.
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> * Be prepared to turn off the controller:
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> turn off Teensy Loader's green "Auto" button and push Teensy's reset button or unplug Teensy USB.
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Compile and load workflow:
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1. Open a keybrd sketch in the Arduino IDE.
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2. Prepare for loosing control of keyboard and mouse.
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3. On the Arduino IDE, click the Upload button.
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4. The Teensy boot loader window opens
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(you might need to press and release the pushbutton on the Teensy circuit board).
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Example keybrd sketches
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-----------------------
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Example keybrd sketches are in the examples and tutorials directories.
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Extension libraries have their example sketches similarly located.
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The example sketch names use the following conventions.
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**keybrd_feature_version.ino**
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where
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* **keybrd** is the library name e.g. keybrd, keybrd_DH
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* **feature** is a distinguishing feature of the keybrd sketch e.g. keyboard name, sound, layout
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* **version** is the sketch's version number (optional)
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Active state and diode orientation
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----------------------------------
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Active state is set in the sketch by variables STROBE_ON and STROBE_OFF.
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The following instructions are for setting active state for a Scanner_uC class
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(Scanner_ShiftRegs74HC165 and Scanner_Port classes is similar).
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For active low:
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* Orient diodes with cathode (banded end) towards the write pins (row)
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* Define strobe on and strobe off in the sketch like this:
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```
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const bool Scanner_uC::STROBE_ON = LOW;
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const bool Scanner_uC::STROBE_OFF = HIGH;
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```
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For active high:
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* Add an external 10k pull-down resistor to each read pin.
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* Orient diodes with cathode (banded end) towards the read pins.
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* Define strobe on and strobe off in the sketch like this:
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```
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const bool Scanner_uC::STROBE_ON = HIGH;
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const bool Scanner_uC::STROBE_OFF = LOW;
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```
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Troubleshooting check list
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--------------------------
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The following is a listing of items to check when a new keybrd sketch or keyboard hardware is having trouble.
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Development-environment items to check:
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* If the keyboard has an I/O expander, power cycle (replug the USB) after loading the HEX file.
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* For compile error:
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```
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'KEY_A' was not declared in this scope
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```
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Where 'KEY_A' could be any scan code.
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Fix this error from the Arduino IDE tool bar: Tools > USB Type > Keyboard + Mouse + Joystick
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* If last line in Arduino IDE says "Low memory available",
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second-to-last line should say "leaving 100 bytes for local variables" or more bytes.
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* In keybrd/src/config_keybrd.h file, read_pins_t defaults to uint32_t.
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If more memory is needed, 8-bit controllers can use uint8_t.
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Sketch items to check:
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* For each row, number of read pins in Row should equal number of keys.
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In this example, row_0 has 2 read pins and 2 keys:
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```
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uint8_t readPins[] = {14, 15};
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uint8_t READ_PIN_COUNT = sizeof(readPins)/sizeof(*readPins);
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Key* ptrsKeys_0[] = { &s_a, &s_b };
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Row_uC row_0(0, readPins, READ_PIN_COUNT, ptrsKeys_0);
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```
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* Some of the constructors take array-element-count arguments, make sure that the correct counts are passed to the constructors. Or use sizeof() like the preceding example.
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* For multi-layered keyboards, the number of codes in each Key_Layered should equal the number of layers.
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Hardware items to check:
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* Continuity of connections
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* 3.3 or 5 volts across power and ground
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* Diode orientation
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* To validate keyboard hardware, modify the simple [keybrd_1_breadboard.ino](../tutorials/keybrd_1_breadboard/keybrd_1_breadboard.ino) sketch.
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Keybrd nomenclature
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-------------------
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**[scancode](http://en.wikipedia.org/wiki/Scancode)** -
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Is a 16-bit integer assigned to a key position on a keyboard.
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The keyboard sends a scancode to the computer for every key press and release.
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**[layers](http://deskthority.net/wiki/Layer)** - are key bindings provided by the keyboard firmware. For example,
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* The classic [IBM PC keyboard](http://en.wikipedia.org/wiki/IBM_PC_keyboard) has one layer.
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* Many compact keyboards have an additional [Fn layer](http://en.wikipedia.org/wiki/Fn_key).
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* The [Neo layout](http://neo-layout.org/index_en.html) has 6 layers.
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**Layer id** - is an integer assigned to a layer.
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**Layer scheme** - is a system for changing layers while typing.
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A single-layer scheme does not change layers.
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**Layout** - is the placement of keys. Key caps are often labeled to show a keyboard's layout.
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**[Matrix](http://pcbheaven.com/wikipages/How_Key_Matrices_Works/)** - is a collection of switches connected by rows and columns.
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**[Bounce](http://en.wikipedia.org/wiki/Switch#Contact_bounce)** -
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Keyboard switches are made of moving contacts.
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When the contacts close, they bounce apart one or more times before making steady contact.
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A debouncer removes the bounce so that a key press is sent to the computer only once.
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**[Modifier key](http://en.wikipedia.org/wiki/Modifier_key)** - is a special key on a computer keyboard that temporarily modifies the normal action of another key when pressed together e.g. Shift, Alt, or Ctrl.
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By themselves, modifier keys usually do nothing; that is, pressing any of the Shift, Alt, or Ctrl keys alone does not trigger any action from the computer.
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**Sketch** - is the name that Arduino uses for a program
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**keybrd sketch** - is an Arduino sketch that uses the keybrd library to define a keyboard firmware.
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<a rel="license" href="https://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" property="dct:title">keybrd guide</span> by <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd" property="cc:attributionName" rel="cc:attributionURL">Wolfram Volpi</a> is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.<br />Permissions beyond the scope of this license may be available at <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd/issues/new" rel="cc:morePermissions">https://github.com/wolfv6/keybrd/issues/new</a>.
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