Docs updated

README.md

@@ -14,7 +14,134 @@ Pulses is a python module to drive LEDs on RPi using PWM (Pulse Width Modulation
 5. `pip install dist/pulses-0.90-py3-none-any.whl`
 
 
+### GPIO and PWM
+For more info on PWM refer to [PWM](https://en.wikipedia.org/wiki/Pulse-width_modulation) and for information on the different GPIO pin you can read [this](https://projects.raspberrypi.org/en/projects/physical-computing/1).
+
+
 ### CLI tool
 
 There is a CLI tool, called `pulses` that you can use to test loops and pulses.
 Run `pulses -h` to read the usage instructions.
+
+### Work model
+
+Each `ledPulse` object has some attributes that define the **pulse**, i.e. the light pattern of the managed LED.
+
+The state of the LED is controlled by the following parameters:
+- **min**: minimum brightness value, I suggest to avoid using `0`, start from `2`;
+- **max**: maximum brightness;
+- **delay**: the base delay between each step of the pattern;
+- **initialMethod**: the method used to calculate the initial steps of the pattern;
+- **loopMethod**: the method used to calculate the steps of the main loop;
+- **finalMethod**: the method used to calculate the final steps of the loop;
+- **delayMethod**: the method used to calculate the delay between each step;
+
+Each pattern starts running 50 steps of initial values, then goes into a repeteated loop, on exit it runs other 50 steps of final values.
+
+To change the above parameters we use a FIFO queue, each time we `set` a new value of one of the above attributes, `ledPulse` will calculate a `tuple` of 3 values, each element of the tuple is in turn an array of 2-ples, each of these 2-ples has the first element as the `value` at a specific step, the second element is the `delay` at a specific step.
+
+- `initialValues`: 50 elements, if an initialMethod is defined, empy otherwise. These are the values that define the pattern of the LED at the start of the new loop;
+- `loopValues`: 100 elements, never empy. These are the values that define the pattern of the LED at the core infinite loop;
+- `finalValues`: 50 elements, if a finalMethod is defined, empy otherwise. These are the values that define the pattern of the LED at the end of a terminating loop;
+
+#### An example
+
+Let's say we define a new pattern that has:
+- `initialMethod = linear`;
+- `loopMethod = cos`;
+- `finalMethod = linear`;
+- `delayMethod = constant`;
+- `delay = 0.01`;
+- `min = 2`;
+- `max = 50`;
+
+The LED starts from brightness `0`, in 50 steps goes linearly to brightness `50`, i.e. the brightness will increate of 1 at each step, there is a delay of `0.01` seconds between each step.
+After these first 50 steps, there will be a repeating loop, looping on `cosine` values, so going from brightness 50 (value of max), down to brightness 2 (value of min), the up again to brightness 50, still with a constant delay of 0.01 between each step.
+The moment we will add a new tuple of values to the queue, using the `set()` method, the worker will exit from the repeating loop, run on 50 steps of the final values and then start with a new similar loop with the new values.
+
+### Class
+
+The only class defined is called `ledPulse`, it is derived from `threading.Thread`
+and takes care of managing the led connected to a PWM GPIO.
+
+#### Methods
+`__init__`: quite simple, the only parameter is the GPIO pin we want to use. This method takes care of:
+- setting up logging;
+- setting up PWM;
+- installing the default methods for loops and delays;
+- set up the queue that we will use later on;
+
+`set()`: change one or more parameter of the state. Bear in mind that each parameter is standalone, so if `min` is set to `2` and `max` is set to `20`, calling `led.set(max=40)` will only change the value of `max` parameter, leaving all the others at the previous value. After successfully setting a parameter, the values for `initial`, `loop`, `final` and `delay` are recalculated and a new tuple is added to the queue;
+
+`run`: this method runs the main loop, that executes first a loop of 50 steps with `initialValues` if this is not empty, then loops on `loopValues` until there is a new tuple in the queue OR the `stop_event` event is set. If there is a new tuple in the queue, the infinite loop on `loopValues` is interrupted, another loop of 50 steps runs through `finalValues` (if not empty) and then we go to the main loop, pull the tuple from the queue and start all over, unless `stop_event` is set; if that's the case we bail out of the external loop and the thread is going to stop;
+
+#### Plugins
+Pulses uses `plugin methods` to calculate the values and delays for each loop.
+These plugin methods are nothing more than python functions, following this prototypes:
+
+- for value plugins:
+```python
+def value_methodname(obj, step):
+    return <value for step>
+```
+
+- for delay plugins:
+```python
+def delay_methodname(obj, step):
+    return <delay value for step>
+```
+
+`obj` is the LED object that uses the method, so you can refer to the attributes of if, like `obj.max` or `obj.min`.
+
+Some examples, that are predefined in Pulses:
+
+```python
+def delay_constant(obj, step):
+    # Delay method: constant
+    return obj.delay
+
+def value_sin(obj, step):
+    """
+    Value method: sin
+    Sinusoidal values, 0-1-0 /\
+    """
+
+    delta = obj.max - obj.min
+    radians = math.radians(1.8 * step)
+    return delta * math.sin(radians) + obj.min
+
+def value_on(obj, step):
+    """
+    Value method: on
+    Always on at "max" brightness
+    """
+
+    return obj.max
+```
+
+You can write your own method plugins, trying to keep them quite simple possibly, then you have to register them before being able to use them.
+You can use two specific methods to register plugins based on their kind:
+
+- `register_delay_method(methodName, function)`;
+- `register_value_method(methodName, function)`;
+
+For example, we can write a function that returns a random value between `min` and `max`:
+
+in `mymodule.py`:
+```python
+def value_random(obj, step):
+    return random.randint(obj.min, obj.max)
+```
+
+then we can register it
+
+```python
+from pulses import ledPulse
+from mymodule import value_random
+
+led = ledPulse(12)
+led.register_value_method('random', value_random)
+led.set(loopMethod='random')
+```
+
+from now on we can call `led.set(loopValue='random')` and our LED will blink with a random value at each step.