adding uboxplot example

Author: jposada202020

circuitpython_uplot/uplot.py

@@ -54,6 +54,7 @@ class Uplot(displayio.Group):
     :param int height: plot box height in pixels
     :param int padding: padding for the plot box in all directions
     :param bool show_box: select if the plot box is displayed
+    :param int background_color: background color in HEX. Defaults to black ``0x000000``
 
     """
 
@@ -65,6 +66,7 @@ def __init__(
         height: int = 100,
         padding: int = 25,
         show_box: bool = True,
+        background_color: int = 0x000000,
     ) -> None:
         if width not in range(50, 481):
             print("Be sure to verify your values. Defaulting to width=100")
@@ -123,7 +125,7 @@ def __init__(
             self._drawbox()
 
         self._plot_palette = displayio.Palette(14)
-        self._plot_palette[0] = 0x000000
+        self._plot_palette[0] = background_color
         self._plot_palette[1] = 0xFFFFFF
         self._plot_palette[2] = self._tickcolor
         self._plot_palette[3] = self._barcolor

docs/quick_start.rst

@@ -31,6 +31,9 @@ The Uplot will be used to display our graphics. The position and the size of the
 could vary. This allows us to have more than 1 plot at the same time in the screen.
 Every one of them with different characteristics or graphs.
 
+Options available are:
+    * backround_color: Allows to change the background color. The default is black.
+
 We tell the microcontroller to display our plot:
 
 .. code-block:: python