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AD9850 DDS Module: 1.3 inch I²C OLED FTW

A white 1.3 inch I²C OLED turns out to be much more readable than the yellow-blue 0.96 inch version:

Arduino with OLED - white 1.3 inch

Arduino with OLED – white 1.3 inch

Of course, after you make it readable, you immediately make room to cram more data on it:

White 1.3 inch OLED on crystal tester

White 1.3 inch OLED on crystal tester

That’s on the proto board with the Arduino and AD9850 DDS ticking away on the left; the bright red MCP4725 DAC will eventually drive the scope’s X axis. Shifting the display to the I²C interface and cleaning up my SPI initialization code worked wonders: the DDS now steps a sine wave at 0.1 Hz (pretty nearly) intervals from 57.0 to 60.3 Hz.

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  1. #1 by madbodger on 2017-06-06 - 11:22

    “Drive the scope’s X axis”? Hmm, you’ve been playing with resonance and a log amplifier, methinks you’ve given away the plot!

    • #2 by Ed on 2017-06-06 - 13:54

      Dang, somebody must’a leaked my Secret Plans to the Interwebs!

      I’ve had those DACs lying around for a while, so it seemed reasonable to at least try building a simpleminded and very narrow-band spectrum analyzer. Calling the DDS a “tracking generator” definitely overstates the case, as there’s no tunable front-end to track, but I think the lashup ought to work reasonably well for this very very very simple case.

      Having so few frequency samples across the crystal’s bandwidth will make for a sketchy display, because the minimum 0.029 Hz/step in a 6 Hz bandwidth produces a whopping 200 points. The HP scope has a storage mode, so it should be at least amusing, if not informative.

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