tfaour
08960c9eec
Quick reset is now the fast/default action; summoning the management menu takes a deliberate hold. Factory reset at ~15s is unchanged. Renamed FRAME_COMBO_SOFT_RESET_HOLD_MS -> FRAME_COMBO_MENU_HOLD_MS to match its new meaning. Bumps firmware to 1.4.1.
155 lines
7.9 KiB
Markdown
155 lines
7.9 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 soft-resets the device (config kept); holding ~3s then
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releasing overlays a "scan to manage" QR code on the current photo for
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30 seconds; holding ~15s factory-resets it (clears WiFi/server config,
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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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### Wiring on the Seeed XIAO ESP32-C6
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The XIAO only breaks out 11 GPIOs (0, 1, 2, 16, 17, 18, 19, 20, 21, 22,
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23), so the dev-board defaults above don't fit -- DC/RST/BUSY (GPIO 9,
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10, 11) aren't exposed on this board at all. Built with
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[`build_for_board.sh xiao`](../firmware/README.md#building-for-the-seeed-xiao-esp32-c6-production-board),
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which layers [`firmware/sdkconfig.xiao`](../firmware/sdkconfig.xiao) on
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top of the dev-board defaults, remapping DC/RST/BUSY onto three of the
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remaining free pins:
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| Panel pin | XIAO GPIO | XIAO silkscreen label | Kconfig option |
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| --------- | --------- | ---------------------- | --------------- |
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| CLK | 20 | D9 | `EPD_PIN_CLK` (unchanged) |
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| DIN | 19 | D8 | `EPD_PIN_MOSI` (unchanged) |
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| CS | 18 | D10 | `EPD_PIN_CS` (unchanged) |
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| DC | 16 | D6 | `EPD_PIN_DC` |
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| RST | 17 | D7 | `EPD_PIN_RST` |
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| BUSY | 21 | D3 | `EPD_PIN_BUSY` |
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| VCC | 3.3V | 3V3 | -- |
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| GND | GND | GND | -- |
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The XIAO's silkscreen labels its pins D0-D10, not raw GPIO numbers --
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the table above gives both.
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Buttons (unchanged from the table above -- the XIAO's only three
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ADC/deep-sleep-capable pins, GPIO 0/1/2, are exactly the ones already
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used): next=GPIO2/**D2**, back=GPIO0/**D0**, menu/reset=GPIO1/**D1**.
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That leaves GPIO22/**D4** and GPIO23/**D5** free, e.g. for the optional
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VBUS mains-sense divider described under
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[Battery](#battery-optional-xiao-esp32-c6) below.
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`sdkconfig.xiao` also sets `FRAME_XIAO_ANTENNA_INIT=y`, which powers
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the XIAO's onboard RF switch and selects its ceramic antenna at boot
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(GPIO3/14, internal to the board -- not part of the wiring above).
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Without it, WiFi doesn't reliably work on this board at all: the radio
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comes up and logs look normal (e.g. the softAP starts and prints its
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SSID/password) but the switch's control pins are left floating, so
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nothing actually reaches the antenna -- the AP never becomes visible to
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a scan, and a station connection would fail to associate the same way.
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Seeed's own Arduino board package does this automatically; plain
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ESP-IDF (what this firmware uses) doesn't, hence the explicit init.
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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: two equal-value resistors in series from BAT+ to
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GND (200k is the reference value, but any matched pair works -- it's
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a ratio divider, so what matters is the two resistors matching each
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other, not the absolute value; higher values just draw less constant
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current from the battery, e.g. ~10uA for 200k+200k vs ~2uA for
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1M+1M, at the cost of a slightly noisier ADC reading from the higher
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source impedance -- not noticeable in practice up to around 1M given
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how coarse the percent curve already is). Midpoint to GPIO0/A0
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(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) -- except
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`FRAME_BATTERY_ADC_GPIO`, which [`firmware/sdkconfig.xiao`](../firmware/sdkconfig.xiao)
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turns on (GPIO0) by default for XIAO builds, since that's the one
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board this feature was designed for. Mains detection stays off by
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default even there; set `FRAME_VBUS_SENSE_GPIO` yourself if you wire
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that divider too.
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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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