219 lines
11 KiB
Markdown
219 lines
11 KiB
Markdown
keybrd Library User's Guide
|
|
===========================
|
|
keybrd is a library for creating custom-keyboard firmware.
|
|
This guide shows how to:
|
|
* set up the Arduino development environment
|
|
* install the keybrd library
|
|
* compile and load keybrd firmware
|
|
|
|
The Arduino development environment is free and simple as possible.
|
|
Its easy for novice programmers to setup and learn.
|
|
|
|
Who this guide is for
|
|
---------------------
|
|
This guide is for anyone who wants to use the keybrd library to develop keyboard firmware.
|
|
|
|
A reader with programming experience, but no C++ experience, would understand the tutorials well enough to modify existing keybrd sketches.
|
|
An experienced C++ programmer would be able to write original sketches and classes.
|
|
|
|
The library is written in the C++ language.
|
|
keybrd sketches use keybrd classes, objects pointers, aggregation, and static class variables.
|
|
|
|
Microcontroller board requirements
|
|
----------------------------------
|
|
The keybrd library works with Teensy and Arduino compatible boards with at least 2 KB SRAM.
|
|
|
|
[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.
|
|
|
|
Getting started with Teensy, Arduino IDE, and keybrd
|
|
----------------------------------------------------
|
|
The Arduino IDE is used to
|
|
|
|
1. edit sketches
|
|
2. compile sketches into HEX files
|
|
3. load the HEX file onto the microcontroller
|
|
|
|
Teensyduino is a software add-on for the Arduino IDE that allows it to compile to Teensy.
|
|
|
|
[Teensy Getting Started](http://www.pjrc.com/teensy/first_use.html) is a good way to familiarize yourself with Teensy.
|
|
[Arduino Development Environment](http://arduino.cc/en/guide/Environment) is a brief description.
|
|
|
|
The following steps create an Arduino development environment for keybrd sketches.
|
|
|
|
### Install Arduino IDE and Teensyduino
|
|
The following install steps are modified from the [Teensyduino download page](https://www.pjrc.com/teensy/td_download.html).
|
|
|
|
For Linux:
|
|
|
|
1. Download and extract the Arduino software to the /opt directory:
|
|
|
|
/opt/arduino-1.x.x
|
|
|
|
2. The "Linux udev rules" link is at top right of page.
|
|
Save the teensy.rules file in /etc/udev/rules.d/
|
|
|
|
3. "Teensyduino Files" installer links are at top of page.
|
|
Download the installer to your Downloads directory.
|
|
Make the installer executable:
|
|
|
|
$ chmod 755 teensyduino.64bit
|
|
|
|
Run the teensyduino installer and fill the form fields:
|
|
|
|
Arduino location to install Teensyduino: /opt/arduino-1.x.x
|
|
Libraries to Install: keybrd
|
|
|
|
4. Launch Arduino IDE from /opt/arduino-1.x.x/arduino
|
|
|
|
### Install keybrd extension libraries
|
|
The keybrd library contains the foundation classes for creating a keyboard firmware.
|
|
For emphasis, it is sometimes referred to as the "core keybrd library".
|
|
|
|
keybrd extension libraries contain additional classes that extend the keyboard library.
|
|
keybrd extension library names are prefixed with "keybrd_".
|
|
|
|
Instructions for installing Arduino libraries are at: http://www.arduino.cc/en/Guide/Libraries
|
|
|
|
The default location for Arduino libraries is ~/Documents/Arduino/libraries/.
|
|
|
|
For example, the DodoHand keyboard requires the core keybrd library and the keybrd_DH extension library be installed.
|
|
After installing the libraries, my Arduino directory looks like this:
|
|
* ~/Documents/Arduino/libraries/keybrd/
|
|
* ~/Documents/Arduino/libraries/keybrd_DH/
|
|
|
|
### Setup Arduino IDE for compiling keybrd firmware
|
|
From the Arduino IDE tool bar, select:
|
|
* Tools > Board > Teensy LC (or whatever board you are using)
|
|
* Tools > USB Type > Keyboard + Mouse + Joystick
|
|
|
|
These are optional:
|
|
* File > Preferences > Compiler warnings: All
|
|
* File > Preferences > check: Use external editor
|
|
|
|
### Compile and load keybrd sketch
|
|
If it isn't already plugged in, plug the USB cable into the computer and controller.
|
|
|
|
> CAUTION: It is possible to loose control of your keyboard when running a keybrd sketch.
|
|
> If the keybrd sketch has a mouse object, it is possible to loose control of your mouse too.
|
|
> USB keyboard protocol is capable of spewing characters and mouse commands at up to 500 per second.
|
|
> Take the following precautions before uploading an untested keybrd sketch to a controller:
|
|
> * Save all files and close dangerous applications.
|
|
> * Park the cursor in an editor opened to a test file.
|
|
> That way you can immediately see if the controller starts spewing characters.
|
|
> * Be prepared to turn off the controller:
|
|
> turn off Teensy Loader's green "Auto" button and push Teensy's reset button or unplug Teensy USB.
|
|
|
|
Compile and load workflow:
|
|
1. Open a keybrd sketch in the Arduino IDE.
|
|
2. Prepare for loosing control of keyboard and mouse.
|
|
3. On the Arduino IDE, click the Upload button.
|
|
4. The Teensy boot loader window opens
|
|
(you might need to press and release the pushbutton on the Teensy circuit board).
|
|
|
|
Example keybrd sketches
|
|
-----------------------
|
|
Example keybrd sketches are in the examples and tutorials directories.
|
|
Extension libraries have their example sketches similarly located.
|
|
|
|
Active state and diode orientation
|
|
----------------------------------
|
|
Active state is set in the sketch by the scanner.
|
|
The following instructions are for setting active state for a Scanner_uC class
|
|
(Scanner_ShiftRegs74HC165 and Scanner_Port classes is similar).
|
|
|
|
For active low:
|
|
* Orient diodes with cathode (banded end) towards the write pins (row)
|
|
* Instantiate the scanner in the sketch with strobeOn LOW, like this:
|
|
```
|
|
Scanner_uC scanner(LOW, readPins, readPinCount);
|
|
```
|
|
|
|
For active high:
|
|
* Add an external 10k pull-down resistor to each read pin.
|
|
* Orient diodes with cathode (banded end) towards the read pins.
|
|
* Instantiate the scanner in the sketch with strobeOn HIGH, like this:
|
|
```
|
|
Scanner_uC scanner(HIGH, readPins, readPinCount);
|
|
```
|
|
|
|
Troubleshooting check list
|
|
--------------------------
|
|
The following is a listing of items to check when a new keybrd sketch or keyboard hardware is having trouble.
|
|
|
|
Development-environment items to check:
|
|
* If the keyboard has an I/O expander, power cycle (replug the USB) after loading the HEX file.
|
|
* For compile error:
|
|
```
|
|
'KEY_A' was not declared in this scope
|
|
```
|
|
Where 'KEY_A' could be any scan code.
|
|
Fix this error from the Arduino IDE tool bar: Tools > USB Type > Keyboard + Mouse + Joystick
|
|
|
|
* If last line in Arduino IDE says "Low memory available",
|
|
second-to-last line should say "leaving 100 bytes for local variables" or more bytes.
|
|
* In keybrd/src/config_keybrd.h file, read_pins_t defaults to uint32_t.
|
|
If more memory is needed, 8-bit controllers can use uint8_t.
|
|
|
|
Sketch items to check:
|
|
* For each row, number of read pins in Row should equal number of keys.
|
|
In this example, row_0 has 2 read pins and 2 keys:
|
|
```
|
|
uint8_t readPins[] = {14, 15};
|
|
uint8_t READ_PIN_COUNT = sizeof(readPins)/sizeof(*readPins);
|
|
|
|
Key* ptrsKeys_0[] = { &s_a, &s_b };
|
|
Row_uC row_0(0, readPins, READ_PIN_COUNT, ptrsKeys_0);
|
|
```
|
|
* The scanner should have enough readPins to cover all the keys of the longest row.
|
|
(rows with fewer keys will have unused read pins)
|
|
* read_pins_t size in keybrd/src/config_keybrd.h file should cover all the read pins.
|
|
* 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.
|
|
* For multi-layered keyboards, the number of codes in each Key_Layered should equal the number of layers.
|
|
|
|
Hardware items to check:
|
|
* Continuity of connections
|
|
* 3.3 or 5 volts across power and ground
|
|
* Diode orientation
|
|
* To validate keyboard hardware, modify the simple [keybrd_1_breadboard.ino](../tutorials/keybrd_1_breadboard/keybrd_1_breadboard.ino) sketch.
|
|
|
|
Debugging:
|
|
Arduino doesn't have a debugger. You can print values like this:
|
|
Keyboard.print(" var="); Keyboard.print(var);
|
|
Keyboard.print(" bitPattern="); Keyboard.println(bitPattern, BIN);
|
|
delay(200);
|
|
The delay is so prints in a loop don't print too fast.
|
|
|
|
Keybrd nomenclature
|
|
-------------------
|
|
**[scancode](http://en.wikipedia.org/wiki/Scancode)** -
|
|
Is a 16-bit integer assigned to a key position on a keyboard.
|
|
The keyboard sends a scancode to the computer for every key press and release.
|
|
|
|
**[layers](http://deskthority.net/wiki/Layer)** - are key bindings provided by the keyboard firmware. For example,
|
|
* The classic [IBM PC keyboard](http://en.wikipedia.org/wiki/IBM_PC_keyboard) has one layer.
|
|
* Many compact keyboards have an additional [Fn layer](http://en.wikipedia.org/wiki/Fn_key).
|
|
* The [Neo layout](http://neo-layout.org/index_en.html) has 6 layers.
|
|
|
|
**Layer id** - is an integer assigned to a layer.
|
|
|
|
**Layer scheme** - is a system for changing layers while typing.
|
|
A single-layer scheme does not change layers.
|
|
|
|
**Layout** - is the placement of keys. Key caps are often labeled to show a keyboard's layout.
|
|
|
|
**[Matrix](http://pcbheaven.com/wikipages/How_Key_Matrices_Works/)** - is a collection of switches connected by rows and columns.
|
|
|
|
**[Bounce](http://en.wikipedia.org/wiki/Switch#Contact_bounce)** -
|
|
Keyboard switches are made of moving contacts.
|
|
When the contacts close, they bounce apart one or more times before making steady contact.
|
|
A debouncer removes the bounce so that a key press is sent to the computer only once.
|
|
|
|
**[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.
|
|
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.
|
|
|
|
**Sketch** - is the name that Arduino uses for a program
|
|
|
|
**keybrd sketch** - is an Arduino sketch that uses the keybrd library to define a keyboard firmware.
|
|
|
|
<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>.
|