[epaper_spi] Add UC8179 BWR support

[candrews]

Description

Pull request in esphome with YAML changes (if applicable):

• [epaper_spi] - Add UC8179 BWR support esphome#19654

Checklist

• I am merging into next because this is new documentation that has a matching pull-request in esphome as linked above.
  or

• I am merging into current because this is a fix, change and/or adjustment in the current documentation and is not for a new component or feature.

• Link added in /src/content/docs/components/index.mdx when creating new documents for new components or cookbook.

[esphome]

As this is a feature matched with a PR in https://github.com/esphome/esphome, please target your PR to the next branch and rebase.

[esphome]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[esphome]

As this is a feature matched with a PR in https://github.com/esphome/esphome, please target your PR to the next branch and rebase.

Base branch has been corrected - dismissing previous review.

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Base branch has been corrected - dismissing previous review.

[esphbot]

PR Review — [epaper_spi] Add UC8179 BWR support

Small, accurate docs addition for the UC8179 BWR panel. It can merge; the notes below are non-blocking.

The new invert_red option is in the Configuration Variables list in the existing style (bold key, italic Optional, type, default), and it explains the panel behaviour behind it (OTP waveforms with inverted red encoding). The PR targets next, which is correct because it has a matching esphome PR.

• New panel row sits after WeAct-* instead of in alphabetical order, and the Various manufacturer and bare part numbers need a short explanation
• The invert_red text says "e.g." for supported models; it should name them and give the default for each (could not be checked against esphome#19654)
• Should the new UC8179 model be added to the busy-pin inverted: true note, as Waveshare-7.5in-V2 is? (could not be checked)
• UC8179 controller link uses the description as link text and points to a reseller-hosted PDF

---

🟢 Suggestions

1. New panel row is out of order and breaks the naming pattern
src/content/docs/components/display/epaper_spi.mdx:60

The rest of the "Supported display panels" table is sorted alphabetically by display name (GooDisplay, Waveshare, WeAct). This row is added at the end, so 7.5in-bv3-bwr-xsrupb comes after WeAct-4.2in-3c. Readers who scan the table for a model name will expect it at the top.

Every other panel row also names a real manufacturer and either links to a product page or gives a short description. Here the manufacturer is Various, and the part numbers are listed with no explanation. One clause would help, for example: "Generic 7.5" BWR panel sold under part numbers FPC-8612 / DEPG0750RWF86BF30 / XSRUPB-2025". That tells users how to recognise their panel, which matters more here because the model name does not identify a vendor.

The row is also longer than the 120-character limit in CONTRIBUTING.md. Several existing rows already break that limit, so this is minor.

Fix: move the row to the top of the table (or wherever the model sorts) and add a short note explaining what the part numbers mean.

| 7.5in-bv3-bwr-xsrupb      | Various             | 7.5" 3-color e-paper (800x480, UC8179) - FPC-8612, DEPG0750RWF86BF30, XSRUPB-2025 |

2. `invert_red` description does not say which models accept it or what the default is elsewhere
src/content/docs/components/display/epaper_spi.mdx:114-116

"Only available for models that support it (e.g. 7.5in-bv3-bwr-xsrupb)" does not tell users which models those are. If someone sets invert_red on a model that does not support it, they will get a config error and the docs will not explain why. The text gives the default only for 7.5in-bv3-bwr-xsrupb, so the default for any other supported model is unknown.

I could not check this against esphome/esphome#19654 from this checkout. If 7.5in-bv3-bwr-xsrupb is the only model that accepts the option, say so directly, for example: "Only supported by the 7.5in-bv3-bwr-xsrupb model, where it defaults to true." If more models accept it, list them and give the default for each.

Also consider saying when a user would change it: "Set to false if red areas render as white and white areas as red." Users usually reach this option from a symptom like that, not from knowing their panel's OTP encoding.

- **invert_red** (*Optional*, boolean): Invert the red color plane. Some BWR e-paper panels with OTP waveforms use
  inverted red encoding (0 = red, 1 = no red). Only available for models that support it (e.g. `7.5in-bv3-bwr-xsrupb`).
  Defaults to `true` for the `7.5in-bv3-bwr-xsrupb` model.

3. UC8179 link uses the description as link text and points to a reseller's PDF
src/content/docs/components/display/epaper_spi.mdx:39

Other rows in the controller table either link with the URL as the link text or have no link. This row turns the whole description into the link text, which reads differently from the rows around it.

The target is a datasheet hosted by buydisplay.com, a reseller, rather than by UltraChip. Reseller download paths tend to move, so the link is more likely to break than a manufacturer URL.

Fix: keep the description as plain text and add the link after it (for example ... variants). [Datasheet](https://www.buydisplay.com/download/ic/UC8179.pdf)). This change is not needed for the BWR feature, so it can also be dropped from this PR.

| UC8179                 | UltraChip    | [E-paper controller used by 800x480 7.5" panels (mono and 3-color variants)](https://www.buydisplay.com/download/ic/UC8179.pdf) |

---

Checklist

• Targets correct branch (next for new feature)
• Configuration variable formatting follows CONTRIBUTING.md
• Option description is complete (applicability and defaults) — suggestion ＃2
• Tables are consistently ordered and formatted — suggestion ＃1, suggestion ＃3
• No hardcoded secrets

---

Automated review by Kōan (Claude) HEAD=c92690c 50s

[esphbot]

Tip

No blocking issues found — ready to merge.

[candrews]

• Should the new UC8179 model be added to the busy-pin inverted: true note, as Waveshare-7.5in-V2 is? (could not be checked)

No, it should not.