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docs(hardware): switch display to GDEY0579T93 with DESPI-c579

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Strip-aspect 5.79" panel (792×272) replaces the page-shaped 7.5" choice.
Reflows the v0.1 screen layout, framebuffer memory budget, and spike 2
acceptance to validate the SSD1683-class controller path or fall back to
a ~300 LoC custom embedded-hal driver.
This commit is contained in:
Julien Calixte
2026-05-14 12:27:33 +02:00
parent 490e2930e3
commit 421270cdf2
3 changed files with 45 additions and 27 deletions
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50
docs/v0.1-mvp-product.md
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@@ -96,34 +96,46 @@ create remote repos.
## Screen layout
Waveshare 7.5" V2 — 800×480, 1-bit.
GDEY0579T93 — 5.79", **792×272**, 1-bit, partial refresh capable. Wide
strip aspect (~2.9:1) — biases the UX toward "current line and recent
context," not a full page.
```
┌──────────────────────────────────────────────────────────────┐
│ notes.md ● 14:02:33 │ ← header (1 line)
├──────────────────────────────────────────────────────────────┤
│ │
│ Lorem ipsum dolor sit amet, consectetur adipiscing elit. │
│ Sed do eiusmod tempor incididunt ut labore et dolore magna │
│ aliqua. │
│ │ ← edit area
│ The quick brown fox jumps over the lazy▎ │ (cursor block)
│ │
│ ... │
│ │
├──────────────────────────────────────────────────────────────┤
│ INSERT • unsaved • Wi-Fi ✓ │ ← status (1 line)
└──────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────────────┐
│ notes.md ● 14:02:33 │ ← header
├─────────────────────────────────────────────────────────────────────────────────────┤
│ Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor │
│ incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud │
│ exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. │
│ │
│ Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu │
│ fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in │ ← edit area
│ culpa qui officia deserunt mollit anim id est laborum. │ (~11 lines)
│ │
│ The quick brown fox jumps over the lazy▎ │ (cursor block)
│ │
│ │
│ │
├─────────────────────────────────────────────────────────────────────────────────────┤
│ INSERT • unsaved • Wi-Fi ✓ │ ← status
└─────────────────────────────────────────────────────────────────────────────────────┘
```
- Header: filename, dirty indicator (●/○), wall clock if Wi-Fi has set time.
- Header: filename, dirty indicator (●/○), wall clock if SNTP has set time.
- Status: mode (always `INSERT` in v0.1), save state, Wi-Fi state. After a
`Ctrl-S` / `Ctrl-G`, status briefly shows the action result (saved at /
pushed `abc1234` / error message) then returns to default.
- Cursor: solid block at the insertion point. **No blink.**
Fonts: one mono font, embedded in firmware. Probably IBM Plex Mono at a size
that gives ~70 columns and ~25 lines of edit area.
Fonts: one mono font, embedded in firmware. Target sizing: a 14 px mono
glyph at roughly 8 px advance gives ~95 columns × ~11 visible lines of edit
area after header (16 px) and status (16 px) bars. Final size tuned during
spike 2 against real legibility on the panel.
**UX consequence of the strip aspect:** the cursor stays near the bottom of
the visible area during normal typing; the edit area scrolls one line at a
time. There is no "page" — just a continuously advancing strip. Embrace it,
don't fight it.
## Error UX

9
docs/v0.1-mvp-technical.md
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@@ -73,8 +73,11 @@ We do **not** try to build the whole stack and turn it on. Each spike below
is a small program that proves one risk before we commit to the next layer.
1. **Spike 1 — Blink.** Confirm toolchain, flash, and basic GPIO.
2. **Spike 2 — EPD.** Drive the 7.5" panel with `epd-waveshare`; full refresh
"hello world." Validates SPI wiring, panel timings.
2. **Spike 2 — EPD.** Drive the GDEY0579T93 (via DESPI-c579 breakout) over
SPI; full refresh "hello world." Validates SPI wiring, panel timings, and
— critically — whether `epd-waveshare` already supports the panel's
controller (SSD1683-class) or whether we write a thin custom driver
against `embedded-hal`. Either way, ~300 LoC; this spike answers which.
3. **Spike 3 — SD.** Mount FAT, read/write a file. Validates SPI sharing with
EPD (or separate bus if needed).
4. **Spike 4 — USB host.** Enumerate the Nuphy as a boot-protocol HID
@@ -173,7 +176,7 @@ ESP32-S3-N16R8: 512 KB SRAM + 8 MB PSRAM. We budget conservatively.
|---|---|---|
| Internal SRAM | ~120 KB | task stacks, DMA buffers, hot code paths |
| Internal SRAM | ~80 KB | mbedtls runtime (TLS handshake working set) |
| PSRAM | ~256 KB | EPD framebuffer (800×480×1 = 48 KB) + shadow + glyph cache |
| PSRAM | ~128 KB | EPD framebuffer (792×272×1 ≈ 27 KB) + shadow + glyph cache |
| PSRAM | ~512 KB | rope buffer + edit history headroom |
| PSRAM | ~1.5 MB | gitoxide working set during push (pack delta, etc.) |
| PSRAM | rest | heap headroom |