tfaour
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Build and push server image / build-and-push (push) Successful in 32s
Battery (firmware + server, disabled by default): new battery.c reads a 2x200k voltage divider via ADC oneshot with curve-fitting calibration (the ESP32-C6's scheme), maps through a piecewise LiPo discharge curve, and restores the pin to button duty after each read -- the settled XIAO ESP32-C6 design shares the back button's GPIO0/A0, time-shared per wake. Skipped entirely when on mains (a 2x100k VBUS divider into a spare digital pin -- the 5V pin is dead on battery power, so presence = mains, where the charging voltage would read misleadingly full) or when the reading is implausible. The manage overlay gains a battery region (static outline glyph + "NN%", below the manage QR, all menu levels), and the device POSTs to the new /frame/battery endpoint after a successful fetch; the server stores percent + as-of timestamp, exposed via /api/queue and shown in the web UI. FRAME_BATTERY_ADC_GPIO / FRAME_VBUS_SENSE_GPIO default to -1 (fully inert on the dev board); compile-verified both disabled and enabled, hardware bring-up deferred until the ordered XIAO + batteries arrive. Orientation (server-side only): new config setting + web UI dropdown (landscape / portrait / landscape_flipped / portrait_flipped). Photos are composed/cropped at the logical hanging shape (portrait crops at 480x800, so face-aware crops match how the frame actually hangs), then rotated losslessly into the panel's native 800x480 byte layout after dithering -- the device never knows. Face-label anchors are transformed through the same rotation (logical_to_native()) so they stay attached to faces on rotated frames. Known documented limitation: the on-device manage overlay still renders in native orientation, so it appears sideways on a portrait-hung frame (QRs scan at any rotation; text reads sideways).
101 lines
4.8 KiB
Markdown
101 lines
4.8 KiB
Markdown
# Hardware
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## Parts
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- An ESP32-C6 dev board (e.g. ESP32-C6-DevKitC-1). Needs 8MB flash --
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see [`firmware/sdkconfig.defaults`](../firmware/sdkconfig.defaults) and
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[`firmware/partitions.csv`](../firmware/partitions.csv) if yours differs.
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- [Waveshare 7.3" E Ink Spectra 6 (E6) panel](https://www.waveshare.com/7.3inch-e-paper-hat-e.htm) --
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800x480, 6-color, SPI.
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- A USB cable for flashing/power.
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## Wiring
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The panel connects over SPI plus three control lines (data/command, reset,
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busy). Defaults below match the reference build and are set in
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[`firmware/components/epd7in3e/Kconfig`](../firmware/components/epd7in3e/Kconfig) --
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override via `idf.py menuconfig` under **E-Paper Display (epd7in3e)
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Configuration** if your wiring differs.
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| Panel pin | ESP32-C6 GPIO | Kconfig option |
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| --------- | ------------- | ----------------- |
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| CLK | 20 | `EPD_PIN_CLK` |
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| DIN | 19 | `EPD_PIN_MOSI` |
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| CS | 18 | `EPD_PIN_CS` |
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| DC | 9 | `EPD_PIN_DC` |
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| RST | 10 | `EPD_PIN_RST` |
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| BUSY | 11 | `EPD_PIN_BUSY` |
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| VCC | 3.3V | -- |
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| GND | GND | -- |
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Optionally, three buttons, all wired the same way -- momentary push button
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between the GPIO and GND, no external resistor needed (the firmware
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enables each pin's internal pull-up, so it idles high and reads low when
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pressed):
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- **Next photo (GPIO2)**: a normal press skips immediately to the next
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photo; see
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[`firmware/README.md`](../firmware/README.md#skipping-to-the-next-photo).
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- **Back photo (GPIO0)**: a normal press returns to the previously-shown
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photo; see
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[`firmware/README.md`](../firmware/README.md#going-back-to-the-previous-photo).
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- **Menu / reset (GPIO1)**: one button, three actions by hold duration --
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a quick press overlays a "scan to manage" QR code on the current photo
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for 30 seconds; holding ~3s then releasing soft-resets the device
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(config kept); holding ~15s factory-resets it (clears WiFi/server
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config, reprovisions); see
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[`firmware/README.md`](../firmware/README.md#managing-the-queue-soft-resetting-and-factory-resetting).
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All three pins were picked because they're within GPIO 0-7 -- the only
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pins the ESP32-C6 can wake from deep sleep on -- aren't strapping pins,
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and aren't already used by the panel wiring above. Also, not
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incidentally, GPIO 0-7 is *all* the deep-sleep-wakeup-capable pins this
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chip has (`SOC_RTCIO_PIN_COUNT` is 8) -- worth knowing if you're
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targeting a compact board like the Seeed XIAO ESP32-C6, which only
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breaks out 3 of them (GPIO0/1/2). These three buttons were deliberately
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designed to fit exactly that budget: two dedicated pins for the
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actions where instant, unambiguous response matters most (next, back),
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and everything else folded onto the third pin via hold duration instead
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of needing its own pin.
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A couple of things worth knowing if you pick different pins:
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- **Avoid the ESP32-C6's strapping pins** (GPIO 4, 5, 8, 9, 15) and the
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USB-JTAG pins (12, 13) where possible -- strapping pins are sampled at
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reset to select boot mode. The reference wiring above already uses
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GPIO9 for DC, which *is* a strapping pin; it's only sampled during
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power-on/reset, so it's safe once the app is running, but if
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flashing/boot ever misbehaves on your board, check whether the panel is
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pulling that line low during reset.
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- The panel's SPI interface is rated well above the firmware's default
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4MHz clock (`EPD_SPI_CLOCK_HZ`), but breadboard/dupont-wire connections
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are often unreliable much past a few MHz. Raise it once your physical
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wiring is confirmed solid.
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## Battery (optional, XIAO ESP32-C6)
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For a battery-powered build on the Seeed XIAO ESP32-C6 (which has
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BAT+/BAT- charge pads on its underside and charges over USB-C):
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- A 1S 3.7V LiPo **with an integrated protection circuit** (the board
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does no low-voltage cutoff of its own), soldered or JST-PH-pigtailed
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to the BAT pads. JST-PH polarity is not standardized -- verify with a
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multimeter before connecting.
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- Battery level sense: 2x200k divider from BAT+ to GND, midpoint to
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GPIO0/A0 (shared with the back button -- deliberate, see
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[`firmware/README.md`](../firmware/README.md#battery-xiao-esp32-c6)).
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- Optional mains detection: 2x100k divider from the 5V pin to GND,
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midpoint to a spare GPIO (e.g. 22).
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Both features are off by default in firmware
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(`FRAME_BATTERY_ADC_GPIO`/`FRAME_VBUS_SENSE_GPIO` = -1).
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## Power
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The device spends nearly all its time in deep sleep, waking briefly once
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an hour (configurable, see the server's web UI) to fetch and display a
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photo. A full-color refresh on this panel takes 15-30+ seconds and draws
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more current than deep sleep by a wide margin -- expect battery life (if
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not running from USB power) to be dominated by refresh frequency, not
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sleep current.
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