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drivers/display/ssd1306.py: Add support for 72x40 displays.

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The 72x40 OLED requires selecting the internal IREF, as opposed to the
default external IREF.  This is an undocumented feature in the SSD1306
datasheet, but is present in the SSD1315 datasheet.  It's possible the
72x40 OLED is actually using the newer SSD1315 controller.  Sending the
IREF select command to SSD1306 displays has no effect on them, so it's
added to the init_display() instead of wrapping in an "if width = 72".

Also tested on a 128x64 OLED using the SSD1315 controller (smaller ribbon
cable) and the proposed change has no effect on the display, as the module
comes with the correct current limiting resistor.  Internal and external
IREF work the same.

Fixes issue #7281.
This commit is contained in:
Mike Causer 2021-06-17 12:49:14 +10:00 committed by Damien George
parent 89945b1989
commit bc7822d8e9
1 changed files with 8 additions and 4 deletions
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12
drivers/display/ssd1306.py
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@ -15,6 +15,7 @@ SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40) SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xA0) SET_SEG_REMAP = const(0xA0)
SET_MUX_RATIO = const(0xA8) SET_MUX_RATIO = const(0xA8)
SET_IREF_SELECT = const(0xAD)
SET_COM_OUT_DIR = const(0xC0) SET_COM_OUT_DIR = const(0xC0)
SET_DISP_OFFSET = const(0xD3) SET_DISP_OFFSET = const(0xD3)
SET_COM_PIN_CFG = const(0xDA) SET_COM_PIN_CFG = const(0xDA)
@ -63,6 +64,8 @@ class SSD1306(framebuf.FrameBuffer):
0xFF, # maximum 0xFF, # maximum
SET_ENTIRE_ON, # output follows RAM contents SET_ENTIRE_ON, # output follows RAM contents
SET_NORM_INV, # not inverted SET_NORM_INV, # not inverted
SET_IREF_SELECT,
0x30, # enable internal IREF during display on
# charge pump # charge pump
SET_CHARGE_PUMP, SET_CHARGE_PUMP,
0x10 if self.external_vcc else 0x14, 0x10 if self.external_vcc else 0x14,
@ -92,10 +95,11 @@ class SSD1306(framebuf.FrameBuffer):
def show(self): def show(self):
x0 = 0 x0 = 0
x1 = self.width - 1 x1 = self.width - 1
if self.width == 64: if self.width != 128:
# displays with width of 64 pixels are shifted by 32 # narrow displays use centred columns
x0 += 32 col_offset = (128 - self.width) // 2
x1 += 32 x0 += col_offset
x1 += col_offset
self.write_cmd(SET_COL_ADDR) self.write_cmd(SET_COL_ADDR)
self.write_cmd(x0) self.write_cmd(x0)
self.write_cmd(x1) self.write_cmd(x1)