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Streaming Media Player: OLED Weirdness

Of late, the OLED displays on two RPi 3 streaming players (the others are RPi 2) have occasionally gone blank, while the players continue to work fine. I checked the logs, swapped MicroSD cards, rebuilt the images, and generally screwed around, all to no avail. The SH1106 controller has a command containing a single bit to blank the display and, perhaps, an SPI data transfer error could shut it off.

This is much harder to explain:

Mirror-image OLED display

Mirror-image OLED display

There’s a hardware command to flip the display top-to-bottom, not left-to-right. The Luma OLED driver can rotate the display in 90° increments, but AFAICT not reflect it.

Yes, they’re networked, but, no, they’re not directly exposed to the Intertubes.

Changing streams had no effect. Shutting down and rebooting restored normal operation.

There’s been exactly one such failure so far, so I lack evidence.

I have no clue what’s going on.

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  1. #1 by david on 2017-10-03 - 14:31

    Have you tried the flip-top-to-bottom hardware mode? Maybe their idea of “top” isn’t your idea of “top”. :)

    • #2 by Ed on 2017-10-03 - 15:29

      I’m sure it’s not! [grin]

      However, I may have found the culprit: the Luma library sets the default SPI clock way higher than the SH1106 data sheet seems to allow, at least for most values of Vcc. Digging into the Luma source unearthed an obscure keyword parameter and I’m trying a 1 MHz clock in the hope the mysterious failures will Go Away. I’ll write things up in a while.

  2. #3 by tantris on 2017-10-03 - 20:45

    Possible explanations listed by likelihood:
    1. Secret, undocumented controller code that got activated by clock glitches.
    2. Since Chinese can be written vertically, David’s explanation might be right,
    3. Enantiomer
    4. For every object there exists a mirrored one in a parallel universe. There shouldn’t be any links….
    5. They are trying to contact you.
    6. You faked the picture to boost your blog ratings, because you need the ad money for a new recumbant.

    • #4 by Ed on 2017-10-04 - 08:13

      Point 1 seems likely, perhaps triggered by an overly speedy clock. Testing (i.e., listening to background music) continues apace.

      I like the mirror universe notion: we’re the ones living behind the mirror! Paging Alice in three, two, one …

  1. Streaming Radio Player: OLED SPI Speed Fix | The Smell of Molten Projects in the Morning

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