Adding much more to README, and adding simple HID keys example.

README.md

@@ -12,7 +12,7 @@ individual keys and the whole Keybow (a collection of Key instances).
 
 ![Keybow 2040 with backlit keys on marble background](keybow-2040-github-1.jpg)
 
-## Getting started quickly!
+# Getting started quickly!
 
 You'll need to grab the latest version of Adafruit's Keybow 2040-flavoured
 CircuitPython, from the link below.
@@ -43,6 +43,12 @@ code, and save it in the `code.py` file on your `CIRCUITPY` drive using your
 favourite text editor. As soon as you save the `code.py` file, or make any other
 changes, then it should load up and run the code!
 
+# In depth
+
+This section covers most of the functionality of the library itself, without
+delving into additional functions like USB MIDI or HID (they're both covered
+later!)
+
 ## Imports and setup
 
 All of your programs will need to start with the following:
@@ -103,7 +109,7 @@ press events. Just don't do it.
 If you need introduce timed events, then you have to go about it in a slightly
 (!!) roundabout fashion, by using `time.monotonic()` a constantly incremented
 count of seconds elapsed, and use it to check the time elapsed since your last
-event, for example:
+event, for example you could do this inside your `while True` loop:
 
 ```
 time_interval = 10
@@ -157,7 +163,10 @@ If we want to check whether key 0 is pressed, we can do so as follows:
 ```
 keys = keybow.keys()
 
-if keys[0].pressed:
+while True:
+    keybow.update()
+
+    if keys[0].pressed:
         # Do something!
 ```
 
@@ -180,13 +189,19 @@ This means that we could extend the example above to be:
 ```
 keys = keybow.keys()
 
-if keys[0].pressed:
+while True:
+    keybow.update()
+
+    if keys[0].pressed:
         # Do something!
 
-if keys[0].held:
+    if keys[0].held:
         # Do something else!
 ```
 
+The [reactive-press.py example](examples/reactive-press.py) shows in more detail
+how to handle key presses.
+
 ## LEDs!
 
 LEDs can be set either globally for all keys, using the `Keybow` class instance,
@@ -238,6 +253,33 @@ v = 1.0  # Value
 r, g, b = hsv_to_rgb(h, s, v)
 ```
 
+The [rainbow.py example](examples/rainbow.py) shows a more complex example of
+how to animate the keys' LEDs, including the use of the `hsv_to_rgb()` function.
+
+## LED sleep
+
+The `Keybow` class has an `.led_sleep_enabled` attribute that is disabled (set to
+`False`) by default, and an `.led_sleep_time` attribute (set to 60 seconds by
+default) that determines how many seconds need to elapse before LED sleep is 
+triggered and the LEDs turn off.
+ 
+The time elapsed since the last key press is constantly updated when 
+`keybow.update()` is called in your main loop, and if the `.led_sleep_time` is
+exceeded then LED sleep is triggered.
+
+Because keys retain their RGB values when toggled off, when asleep, a tap on any
+key will wake all of the LEDs up at their last state before sleep.
+
+Enabling LED sleep with a sleep time of 10 seconds could be done as simply as:
+
+```
+keybow.led_sleep_enabled = True
+keybow.led_sleep_time = 10
+```
+
+There's also a `.sleeping` attribute that returns a Boolean, that you can check 
+to see whether the LEDs are sleeping or not.
+
 ## Attaching functions to keys with decorators
 
 There are three decorators that can be attached to functions to link that 
@@ -274,3 +316,251 @@ def hold_handler(key):
 while True:
     keybow.update()
 ```
+
+The [decorators.py example](examples/decorators.py) has another example of how
+to use the `.on_hold()` decorator to toggle LEDs on and off when a key is held.
+
+## Key combos
+
+Key combos can provide a way to add additional behaviours to keys that only get
+triggered if a combination of keys is pressed. The best way to achieve this is
+using the `.held` attribute of a key, meaning that the key can also have a 
+`.pressed` behaviour too.
+
+Here's a brief example of how you could do this inside your main loop, with key
+0 as the modifier key, and key 1 as the action key:
+
+```
+keys = keybow.keys
+
+modifier_key = keys[0]
+action_key = keys[1]
+
+while True:
+    keybow.update()
+
+    if modifier_key.held and action_key.pressed:
+        # Do something!
+```
+
+Of course, you could chain these together, to require two modifer keys to be
+held and a third to be pressed, and so on...
+
+The [colour-picker.py example](examples/colour-picker.py) has an example of
+using a modifier key to change the hue of the keys.
+
+# USB MIDI
+
+This covers basic MIDI note messages and how to link them to key presses.
+
+## Setup
+
+USB MIDI requires the `adafruit_midi` CircuitPython library. Download it from
+the link below and then drop the `adafruit_midi` folder into the `lib` folder on
+your `CIRCUITPY` drive.
+
+[Download the Adafruit MIDI CircuitPython library](https://github.com/adafruit/Adafruit_CircuitPython_MIDI)
+
+You'll need to connect your Keybow 2040 with a USB cable to a computer running a
+software synth or DAW like Ableton Live, to a hardware synth that accepts USB
+MIDI, or through a MIDI interface that will convert the USB MIDI messages to
+regular serial MIDI through a DIN connector.
+
+Using USB MIDI, Keybow 2040 shows up as a device with the name 
+`Keybow 2040 (CircuitPython usb midi.ports[1])`
+
+In my testing, Keybow 2040 works with the Teenage Engineering OP-Z quite nicely.
+
+## Sending MIDI notes
+
+Here's a complete, minimal example of how to send a single MIDI note (middle C,
+or MIDI note number 60) when key 0 is pressed, sending a note on message when
+pressed and a note off message when released.
+
+```
+import board
+from keybow2040 import Keybow2040
+
+import usb_midi
+import adafruit_midi
+from adafruit_midi.note_off import NoteOff
+from adafruit_midi.note_on import NoteOn
+
+i2c = board.I2C()
+keybow = Keybow2040(i2c)
+keys = keybow.keys
+
+midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=0)
+
+key = keys[0]
+note = 60
+velocity = 127
+
+was_pressed = False
+
+while True:
+    keybow.update()
+
+    if key.pressed:
+        midi.send(NoteOn(note, velocity))
+        was_pressed = True
+    elif not key.pressed and was_pressed:
+        midi.send(NoteOff(note, 0))
+        was_pressed = False
+```
+
+There'a more complete example of how to set up all of Keybow's keys with 
+associated MIDI notes using decorators in the 
+[midi-keys.py example](examples/midi-keys.py).
+
+The example above, and the `midi-keys.py` example both send notes on MIDI
+channel 0 (all channels), but you can set this to a specific channel, if you
+like, by changing `out_channel=` when you instantiate your `midi` object.
+
+# USB HID
+
+This covers setting up a USB HID keyboard and linking physical key presses to 
+keyboard key presses on a connected computer.
+
+## Setup
+
+USB HID requires the `adafruit_hid` CircuitPython library. Download it from the
+link below and drop the `adafruit_hid` folder into the `lib` folder on your 
+`CIRCUITPY` drive.
+
+[Download the Adafruit HID CircuitPython library](https://github.com/adafruit/Adafruit_CircuitPython_HID)
+
+You'll need to connect your Keybow to a computer using a USB cable, just like
+you would with a regular USB keyboard.
+
+## Sending key presses
+
+Here's an example of setting up a keyboard object and sending a `0` key press
+when key 0 is pressed, using an `.on_press()` decorator:
+
+```
+import board
+from keybow2040 import Keybow2040
+
+import usb_hid
+from adafruit_hid.keyboard import Keyboard
+from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
+from adafruit_hid.keycode import Keycode
+
+i2c = board.I2C()
+keybow = Keybow2040(i2c)
+keys = keybow.keys
+
+keyboard = Keyboard(usb_hid.devices)
+layout = KeyboardLayoutUS(keyboard)
+
+key = keys[0]
+
+@keybow.on_press(key)
+def press_handler(key):
+    keyboard.send(Keycode.ZERO)
+
+while True:
+    keybow.update()
+```
+
+You can find a list of all of the keycodes available at the
+[HID CircuitPython library documentation here](https://circuitpython.readthedocs.io/projects/hid/en/latest/api.html#adafruit-hid-keycode-keycode).
+
+If you wanted to take this a bit further and make a full keymap for your
+keyboard, then you could create a list of 16 different keycodes and then use the
+number of the key press registered by the `press_handler` function as an index
+into your keymap to get the keycode to send for each key.
+
+```
+import board
+from keybow2040 import Keybow2040
+
+import usb_hid
+from adafruit_hid.keyboard import Keyboard
+from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
+from adafruit_hid.keycode import Keycode
+
+i2c = board.I2C()
+keybow = Keybow2040(i2c)
+keys = keybow.keys
+
+keyboard = Keyboard(usb_hid.devices)
+layout = KeyboardLayoutUS(keyboard)
+
+keymap =    [Keycode.ZERO,
+             Keycode.ONE,
+             Keycode.TWO,
+             Keycode.THREE,
+             Keycode.FOUR,
+             Keycode.FIVE,
+             Keycode.SIX,
+             Keycode.SEVEN,
+             Keycode.EIGHT,
+             Keycode.NINE,
+             Keycode.A,
+             Keycode.B,
+             Keycode.C,
+             Keycode.D,
+             Keycode.E,
+             Keycode.F]
+
+for key in keys:
+    @keybow.on_press(key)
+    def press_handler(key):
+        keycode = keymap[key.number]
+        keyboard.send(keycode)
+
+while True:
+    keybow.update()
+```
+
+This code is available in the 
+hid-keys-simple.py example](examples/hid-keys-simple.py).
+
+As well as sending a single keypress, you can send multiple keypresses at once,
+simply by adding them as additional argumemnts to `keyboard.send()`, e.g. 
+`keyboard.send(Keycode.A, Keycode.B)` and so on.
+
+## Sending strings of text
+
+Rather than the incovenience of sending multiple keycodes using
+`keyboard.send()`, there's a different method to send whole strings of text at
+once, using the `layout` object we created.
+
+```
+import board
+from keybow2040 import Keybow2040
+
+import usb_hid
+from adafruit_hid.keyboard import Keyboard
+from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
+from adafruit_hid.keycode import Keycode
+
+i2c = board.I2C()
+keybow = Keybow2040(i2c)
+keys = keybow.keys
+
+keyboard = Keyboard(usb_hid.devices)
+layout = KeyboardLayoutUS(keyboard)
+
+key = keys[0]
+
+@keybow.on_press(key)
+def press_handler(key):
+    layout.write("Pack my box with five dozen liquor jugs.")
+
+while True:
+    keybow.update()
+```
+
+A press of key 0 will send that whole string of text at once!
+
+Be aware that strings sent like that take a little while to  virtually "type",
+so you might want to incorporate a delay using  `keybow.time_of_last_press`, 
+and then check against a `time_elapsed` variable created with 
+`time_elapsed = time.monotonic() - keybow.time_of_last_press`.
+
+Also, be aware that the Adafruit HID CircuitPython library only currently 
+supports US Keyboard layouts, so you'll have to work around that and map any
+keycodes that differ from their US counterpart to whatever your is.

examples/hid-keys-simple.py

@@ -0,0 +1,40 @@
+import board
+from keybow2040 import Keybow2040
+
+import usb_hid
+from adafruit_hid.keyboard import Keyboard
+from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
+from adafruit_hid.keycode import Keycode
+
+i2c = board.I2C()
+keybow = Keybow2040(i2c)
+keys = keybow.keys
+
+keyboard = Keyboard(usb_hid.devices)
+layout = KeyboardLayoutUS(keyboard)
+
+keymap =    [Keycode.ZERO,
+             Keycode.ONE,
+             Keycode.TWO,
+             Keycode.THREE,
+             Keycode.FOUR,
+             Keycode.FIVE,
+             Keycode.SIX,
+             Keycode.SEVEN,
+             Keycode.EIGHT,
+             Keycode.NINE,
+             Keycode.A,
+             Keycode.B,
+             Keycode.C,
+             Keycode.D,
+             Keycode.E,
+             Keycode.F]
+
+for key in keys:
+    @keybow.on_press(key)
+    def press_handler(key):
+        keycode = keymap[key.number]
+        keyboard.send(keycode)
+
+while True:
+    keybow.update()