Merge pull request #2 from adafruit/TheKitty-patch-1

Update to pass and comment

Author: ladyada

examples/il91874_simpletest.py

@@ -1,39 +1,54 @@
-"""Simple test script for 2.7" 264x176 Tri-Color display shield
-
-Supported products:
+"""
+  Simple test script for 2.7" 264x176 Tri-Color display shield
+  Supported products:
   * Adafruit 2.7" Tri-Color ePaper Display Shield
-    * https://www.adafruit.com/product/4229
-  """
+    https://www.adafruit.com/product/4229
+
+  This program only requires the adafruit_il91874 library in /lib
+  for CircuitPython 5.0 and above which has displayio support.
+"""
 
 import time
 import board
 import displayio
 import adafruit_il91874
 
+# Used to ensure the display is free in CircuitPython
 displayio.release_displays()
 
+# Define the pins needed for display use on the Metro
 spi = board.SPI()
 epd_cs = board.D10
 epd_dc = board.D9
 
-display_bus = displayio.FourWire(spi, command=epd_dc, chip_select=epd_cs, baudrate=1000000)
-time.sleep(1)
+# Create the displayio connection to the display pins
+display_bus = displayio.FourWire(spi, command=epd_dc, chip_select=epd_cs,
+                                 baudrate=1000000)
+time.sleep(1)  # Wait a bit
 
-display = adafruit_il91874.IL91874(display_bus, width=264, height=176, highlight_color=0xff0000,
-                                   rotation=90)
+# Create the display object - the third color is red (0xff0000)
+display = adafruit_il91874.IL91874(display_bus, width=264, height=176,
+                                   highlight_color=0xff0000, rotation=90)
 
+# Create a display group for our screen objects
 g = displayio.Group()
 
+# Display a ruler graphic from the root directory of the CIRCUITPY drive
 f = open("/display-ruler.bmp", "rb")
 
 pic = displayio.OnDiskBitmap(f)
+# Create a Tilegrid with the bitmap and put in the displayio group
 t = displayio.TileGrid(pic, pixel_shader=displayio.ColorConverter())
 g.append(t)
 
+# Place the display group on the screen (does not refresh)
 display.show(g)
 
+# Show the image on the display
 display.refresh()
 
 print("refreshed")
 
-time.sleep(120)
+# Do Not refresh the screen more often than every 180 seconds
+#   for eInk displays! Rapid refreshes will damage the panel.
+time.sleep(180)