Ongoing Attempt at Driving CFAL25664C0-021M


New member

I've been having a great deal of trouble getting the CFAL25664C0-021M to do anything, so, maybe someone here could help a body out? I ordered the Multi-Use ZIF Breakout Board, which is linked directly from the page for the OLED display as a "Component Worth Considering", except that the breakout isn't compatible with the CFAL25664C0-021M. Grr!

I laid out my own eval board to try to get this working, schematic here: BreakoutSchematic.png

Note that the headers are broken out to either drive the SPI lines directly via J3, or through a level snifter from J1. Driving directly from a Seeduino set to 3V3, and without the OLED connected, the SCLK and MOSI signals look like this, where ch1 (yellow) is the clock and ch2 (teal) is MOSI:


However, after attaching the OLED, the clock gets pulled low:

Is a buffer needed to drive the clock or something?

The pin assignments for the Seeduino/Arduino were ascertained from the example sketch and are pin8=CS, pin9=RESET, pin10=DC, pin11=MISO, and pin13=SCLK.

Also tried this with a standard Arduino running through the level shifter, and with divider resistors to get the levels to 3.3V (bypassing the level shifter), all with similar results.

For completeness, here's a photo of the eval board:
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CF Kelsey

Staff member
Hi Justine,

I'm sorry to hear you had trouble with the CFAL25664C0-021M and Multi-Use ZIF Breakout Board. The two can be used together by inserting the tail of the display into the 0.3mm ZIF connector (J8), justified all the way so pin 1 is lined up with the top of the connector. The components required by the display must then be soldered on the breakout board for it to be used with the display. You can see the display brought up on the Breakout board in this video.

Are you using our code directly from the webpage?

CF Kelsey

Staff member
In looking more at the picture you included, it looks like you may have the tail pinout reversed. That is - where you have designed to have pin 1 is actually pin 31. Could you check that for me?



If that is what happened, it's likely the display has been damaged due to exceeding maximum voltages on logic pins.


New member
By George, it IS backwards! Wow, thank you so very much for spotting that. I'm filled with that all-too-familiar feeling of simultaneous relief and embarrassment for having an easy fix while eeling stupid for making the mistake in the first place. THANK YOU.

Also, thanks for cluing me in about the breakout board.