Support for 72x40 0.42in OLEDs

Author: mcauser

adafruit_ssd1306.py

@@ -34,6 +34,7 @@
 SET_PAGE_ADDR = const(0x22)
 SET_DISP_START_LINE = const(0x40)
 SET_SEG_REMAP = const(0xA0)
+SET_IREF_SELECT = const(0xAD)
 SET_MUX_RATIO = const(0xA8)
 SET_COM_OUT_DIR = const(0xC0)
 SET_DISP_OFFSET = const(0xD3)
@@ -126,15 +127,14 @@ def init_display(self):
             0xFF,  # maximum
             SET_ENTIRE_ON,  # output follows RAM contents
             SET_NORM_INV,  # not inverted
+            SET_IREF_SELECT,
+            0x30,  # enable internal IREF during display on
             # charge pump
             SET_CHARGE_PUMP,
             0x10 if self.external_vcc else 0x14,
             SET_DISP | 0x01,
         ):  # on
             self.write_cmd(cmd)
-        if self.width == 72:
-            self.write_cmd(0xAD)
-            self.write_cmd(0x30)
         self.fill(0)
         self.show()
 
@@ -177,14 +177,11 @@ def show(self):
         if not self.page_addressing:
             xpos0 = 0
             xpos1 = self.width - 1
-            if self.width == 64:
-                # displays with width of 64 pixels are shifted by 32
-                xpos0 += 32
-                xpos1 += 32
-            if self.width == 72:
-                # displays with width of 72 pixels are shifted by 28
-                xpos0 += 28
-                xpos1 += 28
+            if self.width != 128:
+                # narrow displays use centered columns
+                col_offset = (128 - self.width) // 2
+                xpos0 += col_offset
+                xpos1 += col_offset
             self.write_cmd(SET_COL_ADDR)
             self.write_cmd(xpos0)
             self.write_cmd(xpos1)