Using Small (<500 pix) Monochrome OLED Displays

[Renix]

I do hope there are others interested in sharing info on using these inexpensive displays in various projects. All of the OLEDs I have worked with are based on one form or another of the SSD1322 controller. In most instances, I have used 3 or 4 wire SDI interfacing as it can be fast and compact.

This device works quite different from the full-color display controllers I have used in the past. In the latter, each pixel is individually addressed to specify the color and brightness. This makes small bitmapped fonts and glyphs rather easy to construct.

But the SSD1322 works quite differently. To keep things simple for now, pixel rows can be addressed individually. However, one cannot easily address a single pixel column. Rather one has to write 4 pixel values to the controller before they will be written to the actual display. Being a greyscale display, each pixel is comprised of 4 bits or 16 levels. This means 2-bytes or 16 bits in the form of 3 sequential bytes: command, data, data. This makes it rather complicated to use a typical bitmapped font in C on a microcontroller.

One way around this is to build a bitmapped image in a buffer and write the buffer to the controller. My favorite display is 64x256x4bits. That’s a 8K frame buffer! Rather big for a typical microcontroller. And the frame rate, from a micro over SDI at that size will surely lead to some flicker.

One way around this, if full-frame video is not the goal, is to creat many small frame buffers or fixed multi-row/column symbols or glyphs. These will transfer over SDI quite fast.

More to come.

[bobcat1]

Hi
This type of OLED display was not designed for life video streaming ,only  to display static or low rate data, the best way to use them is to divide the display to several area and update an area at the time of change ,that way will not require a big memory buffer,

All the best

Bobi 

[Renix]

@bobcat1
Yes I agree completely. I have used them to replace VFD displays and my intent is to discuss the trials & tribulations for those who have not worked with them.

Renix

[devetka]

I love those 2color ones (one stripe is one color, e.g. amber, and rest of the display is other color, e.g. white) .. the "stripe" is great for title (top) or status (bottom).. I had some that have double the ram so you can use the display as buffer instead of using up ram on the mcu for the buffer, but the problem is when I order them from ali I never know if the ones that arrive will have the double ram or not

[Renix]

@devetka
I have not seen this type. Got a link to a unit or spec sheet?
I got some of the 64 x 256 mono OLED from Ali and they had straight headers already mounted. I needed RA headers.
What a pain to swap. Good thing I only needed SDI. Id never get all 16 swapped without damage!

[Renix]

Well I’m back for a while. Some health crap came up.
I finished the assembly of the OLED display for the Fluke meters.
They are more complex and expensive than the blue LED module out of the Ukraine by AHOL, but he has dropped of the radar for obvious reasons. When I get to a real computer rather than this iPad, I can post some pictures, but the OLED display in green with the OEM Fluke bezel is as bright as an OEM VFD.

The control module is user programmable to offer a variety of display formats with Logos for different Fluke models 8840A, 8840AF, 8842A etc. There is a demo mode also to exercise the display without connection to the Fluke meter also.

I may start another thread for the Fluke meters specifically.

[Renix]

I have now rebuilt 4 Fluke meters with OLED displays and new front lens. Blue, green and yellow OLEDs look the best. And with colored acrylic material there are several good looking options with each display color.

I have some new PCBs now I need to build that add additional features not originally available in these Fluke meters. The most interesting is a continuity testing function on the lower resistance ranges. Since the display controller knows what mode is selected and what value is displayed, it is possible to turn on an annunciation if resistance is lower than some limit, say 200 ohms. This works best in the medium or fast sample settings as the slow rate takes the Fluke ADC quite some time to take a measurement.

This continuity mode is enabled/disabled from front panel switches.

Of course the blue LED replacement out of Ukrain if much more cost effective if you can get one. I have several modules and complete display PCBs for sale while they last on eBay. Just search for Fluke 8840A display.

[pickit2]

Well I’m back for a while. Some health crap came up.
I finished the assembly of the OLED display for the Fluke meters.

I may start another thread for the Fluke meters specifically.

I just seen this, the forum is for the members, you can start any thread you like.

I find that most OLED displays are fitted badly to the pcb, the two sided tape between the glass  and pcb, looses contact if not fitted in a mount, or glued to the pcb.