luma.oled: Wrong Init Routine for SSD1322 ? / NHD-2.7-12864WD

I’ve been having some issues with the same 2.7 New Haven display. Initially the modified _nhd class seemed to work. But grey ramps were messed up and anitalised text looked seriously wonky. I see that the class was writing out byte values rather than nibble encoded 4bit / 16 grey levels. After some experimentation it looks very much like there’s something interesting going on here.

I /think/ every other nibble controls the alternate scan of the pixel. Very strange. Anyway if I write out data for wxh (rather than wxh/2) and duplicate every pixel into both the upper and lower nibble everything looks great - the ramps now display correctly and text renders as expected - where’s previously values like 240 (prior to send to device) would snap to an incredibly low display value which looks effectively black).

If I write a zero nibble then a 4 but it displays dim but full screen. Same if I write a high nibble then zero. So clearly it needs 8bits per pixel. But it’s doing something with both the top and bottom nibble for that same pixel- seemingly it’s a dual scan on the pixel which I don’t get with the mechanics of how oleds work for precharge cycles etc. but nonetheless it appears to work a /lot/ better.

So sorry to reopen this but I think the nhd init routine / display routines are still wrong for things that aren’t pure black / white.

this is the working ramps. I can upload more images to show the diffs as needed.

I will try and tidy up the copious init routine hacks and submit a PR.

George

If pins 19 and 20 weren’t tie to logic 0 (usually ground) and VDD, then those pins are floating. You won’t have a guarantee of the interface mode. Re-wire your setup and the only pins you can leave not counted are the one labeled N.C. (3, 9, 15, and 18). All VSS pins must be connect to ground.

Shoot me an email if you need further assistance.

Here is the entire mod of the ssd1322:

self.reset()
        self.command(0xFD, 0x12)  # Unlock IC
        self.command(0xAE)  # Display off
        self.command(0xB3, 0x91)  # Display divide clockratio/freq
        self.command(0xCA, 0x3F)  # Set MUX ratio
        self.command(0xA2, 0x00)  # Display offset
        self.command(0xAB, 0x01)  # Display offset
        self.command(0xA0, 0x16, 0x11)  # Set remap & dual COM Line
        self.command(0xC7, 0x0F)  # Master contrast (reset)
        self.command(0xC1, 0x9F)  # Set contrast current
        self.command(0xB1, 0xF2)  # Set default greyscale table
        self.command(0xBB, 0x1F)  # Pre-charge voltage
        self.command(0xB4, 0xA0, 0xFD)  # Display enhancement A (External VSL)
        self.command(0xBE, 0x04)  # Set VcomH
        self.command(0xA6)  # Normal display (reset)
        self.command(0xAF)  # Exit partial display

        self.contrast(0x7F)  # Reset
        self.clear()
        self.show()

I have the NHD-2.7-12864WDW3 and was able to get the SSD1322 driver to work with the following modifications of the ssd1322 class:

self.reset_display()
self.command(0xFD, 0x12)  # Unlock IC
self.command(0xAE)  # Display off
self.command(0xB3, 0x91)  # Display divide clockratio/freq
self.command(0xCA, 0x3F)  # Set MUX ratio
self.command(0xA2, 0x00)  # Display offset
self.command(0xAB, 0x01)  # Display offset
self.command(0xA0, 0x16, 0x11)  # Set remap & dual COM Line
self.command(0xC7, 0x0F)  # Master contrast (reset)
self.command(0xC1, 0x9F)  # Set contrast current
self.command(0xB1, 0xF2)  # Set default greyscale table
self.command(0xBB, 0x1F)  # Pre-charge voltage
self.command(0xB4, 0xA0, 0xFD)  # Display enhancement A (External VSL)
self.command(0xBE, 0x04)  # Set VcomH
self.command(0xA6)  # Normal display (reset)
self.command(0xAF)  # Exit partial display

I added a new method called reset_display to the device class in luma.core.device.py

def reset_display(self):
	from luma.core.util import usleep
	
	self._serial_interface.assert_reset() # pull low
	usleep(400)
	self._serial_interface.negate_reset() # Keep RESET pulled high
	usleep(400)

I also added usleep to luma.core.util.py

def usleep(x):
   time.sleep(x/1000000.0)

Finally, I added two new methods to bitbang class in luma.core.interface.serial.py.

def assert_reset(self):
    if self._RST is not None:
        self._gpio.output(self._RST, self._gpio.LOW)

def negate_reset(self):
    if self._RST is not None:
            self._gpio.output(self._RST, self._gpio.HIGH)

I used the following command line config:

--display=ssd1322 --interface=spi --width=256 --height=64 --spi-bus-speed=16000000

When I used a width of 128, there were horizontal bars (64bit wide) on each side of the display. This was pretty odd, since newhaven lists the display as 128x64. Once I changed the width parameter to 256 the full display was used.

I think I’m still having issues with the fonts that came with luma.examples. I haven’t tried any other fonts. I’m not sure if the default fonts are usable with 256x64 since the wiki does not confirm working with 256x64.

Here is an pic of the default font, C&C Red Alert [INET].ttf, used in sys_info.py

Here is an pic of the font tiny.ttf used in sys_info.py