Auto-detect FPC-7519rev.b panel so old and new MagTags work without manual configuration

[mikeysklar]

Newer MagTag units ship with a different display panel (FPC-7519rev.b) that needs different settings to render grayscale correctly. This updates the example to automatically detect which panel is installed and apply the right settings, so both old and new MagTags work without any manual configuration.

[brentru]

Woah, nice PR! Are you going to integrate this into the Adafruit Arduino SSD1680 library too?

@tyeth - we do this internally, in the WipperSnapper Display component, take a look at this interesting route!

[brentru]

Is there a technical reason this function is sitting in the example?

I feel it'd be best as a method within the SSD1680's __init__ and having it auto-switch to the panel it detects. You'd be able to define the LUTs at module-level, too

[mikeysklar]

top: MagTag SSD1680 (A005)
bottom: MagTag SSD1680 (7519rev.b)

Running PR code.

[mikeysklar]

@brentru -

The autodetect with USER IDs is something @dhalbert originally came up with a few months ago when the SSD1680s rev'd. I just dropped in some more init / LUT settings to clean up the fuzz issues (based on GxEPD2).

I submitted code in Adafruit_EPD pull #96 to support newer panels with the same initialization used here. I did not include autodetect for that library.

How about a detect_panel() at the module level to get it out of the example code? __init__ will be too late as FourWire will claim some pins I need to bitbang for USER ID.

[brentru]

How about a detect_panel() at the module level to get it out of the example code?

That's a good idea if you can not automatically switch, but the user will have to always know to call it.

[mikeysklar]

It might be easier to leave detection in the example code for now.

Happy to consider other options, but I don't want to break away from the norm of how all other Adafruit display libraries work.

One other option to consider would be a wrapper with create_display() calling detect_panel(), but that is kind of funky too.

  display = adafruit_ssd1680.create_display(
      board.EPD_SCK, board.EPD_MOSI, board.EPD_CS,
      board.EPD_DC, board.EPD_RESET, board.EPD_BUSY,
      width=296, height=128, rotation=270, grayscale=True
  )

[brentru]

I'm just not sure if the LUTs should be in the example code, or the module...

[mikeysklar]

Agreed. Let me pretty it up. I'll ping you once I've shuffled some code into the module.

[mikeysklar]

@brentru -

changes

• moved the LUTs into the module
• using detect_ssd1680_panel()
• switched to newer panels (colstart=8 offset) being the default in case we get another address rev
• shrink example ~185 -> ~64 LoC

testing

• confirmed backwards compatibility with original example code and new library (no regression) for FPC-A005
• older mono example still works calling SSD1680()
• new display 0xca correctly detected
• tested CP 10.2.1

  SSD1680 User ID first byte: 0x00
  Detected: FPC-A005 panel (legacy)
  refreshed

  SSD1680 User ID first byte: 0xca
  Detected: FPC-7519rev.b or newer panel
  refreshed

FPC-A005 (top)
FPC-7519rev.b (bottom)
webcam snap from this morning

[brentru]

Looks great - much cleaner example

[mikeysklar]

Thank you. Glad we have something simple to get people going.

[ladyada]

ok wanna merge this?

[mikeysklar]

I'm ready to merge if @brentru is cool with it.

[brentru]

Merge away! 🚢

…

On Mon, May 18, 2026 at 7:56 PM Mikey Sklar ***@***.***> wrote: *mikeysklar* left a comment (adafruit/Adafruit_CircuitPython_SSD1680#40) <#40?email_source=notifications&email_token=AACOW7EBW5VIIYCZO7ZY4OT43OPJXA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINBYGMZDIOBQGMY2M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJNLQOJPWG33NNVSW45C7N5YGK3S7MNWGSY3L#issuecomment-4483248031> I'm ready to merge if @brentru <https://github.com/brentru> is cool with it. — Reply to this email directly, view it on GitHub <#40?email_source=notifications&email_token=AACOW7EBW5VIIYCZO7ZY4OT43OPJXA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINBYGMZDIOBQGMY2M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJNLQOJPWG33NNVSW45C7N5YGK3S7MNWGSY3L#issuecomment-4483248031>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACOW7HXONJOSXI4HVPFXRD43OPJXAVCNFSM6AAAAACY5FAL22VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DIOBTGI2DQMBTGE> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[mikeysklar]

@brentru can you pull the trigger on the merge. I do not have privs. Also will be submitting several more PRs next week for similar models.

[tyeth]

Brent's away until Tuesday. Thanks for this Mikey, it'll be absorbed into wippersnapper too soon.

[mikeysklar]

Thx @tyeth.

Currently working on SSD1675A - SSD1683 to support grayscale. Just a heads up since you are updating Wippersnapper. Some of these might be of interest to you.

I'll be adding updates to this library and Adafruit_EPD.

Also a learn guide to explain the process.

#	Product	Chipset	Status
#4195	2.13" FeatherWing (pre-Apr 2020)	SSD1675A	✅ CP 4-gray working — pux4j LUT + VCOM=0x28
#4195	2.13" FeatherWing (post-Apr 2020)	SSD1680	🔲 Unit not yet in hand
#4687	2.13" Pi Bonnet	SSD1680	🔲 Not started
#4197	2.13" Breakout w/SRAM	SSD1680	🔲 Not started (priority)
#6383	2.13" bare panel	SSD1680	🔲 Not started
#4777	2.9" FeatherWing	SSD1680	🔲 Not started (priority)
#4800	MagTag 2.9"	SSD1680	✅ Reference implementation (done)
#6381	4.2" bare panel	SSD1683	🔲 Not started
#4196	1.54" Breakout w/SRAM + EYESPI	SSD1681	🔲 Not started (OOS)

[tyeth]

@mikeysklar I was going to ping you on that actually, I did a half understood greyscale implementation for the SSD1683, but wondered which was better having little blinka colour understanding, between swapping the LUT bits around for blinka from the ardu copy, or swapping the ram colour bank commands and using the arduino LUT, both resolved the issue. I figured I'd better grab the tri-color and understand it better before pinging anyone. That's just come into stock 3hrs ago, so next week I'll order one, or hope you tackle it before/for me 😁
adafruit/Adafruit_CircuitPython_SSD1683#2
[I have https://www.adafruit.com/product/6381 (greyscale), but wanted to confirm 3colour 6382 works too]

[mikeysklar]

@tyeth - When I was working on the Magtag it came down to five settings. I got lucky since the GxEPD2_4G provided a great starting point with their LUT.

• Two panel variants — same product, different PCB revisions; read a hardware ID byte at startup to tell them apart and load the right settings

• Borrowed the waveform table from GxEPD2_4G — just had to flip the black/white rows since CircuitPython's color convention is opposite
  DC balance tweak — a specific alternating voltage pattern in the waveform eliminated pixel noise

• VCOM voltage tuned by hand — the factory default caused ghosting; 0x24 was the sweet spot for this panel

• Hard reset required before every refresh — the chip goes to sleep after each update; skip the reset and the first SPI command gets eaten

My strategy has been find a decent LUT to get things close and tune from there with Claude and a Webcam closed loop.