Display¶

The 240×240 ST7789 needs a SPI bus, a backlight, fonts, a QR payload, and two pages. Home Assistant gets a Display switch to turn the backlight on or off.

Mock-up from the display code: SoftAP QR, then Wi‑Fi status, live lux, mode, LED state, IP, and a display-on cue. Run-page values are samples.

Pins¶

Signal	GPIO	Set in	Wired in
SCK / SCL	1	`spi`	Display
MOSI / SDA	0	`spi`	same
CS	10	`display`	same
DC	3	`display`	same
RST	7	`display`	same
BL	21	`output`	same

Silk on the module may say SCL or SCK for the clock — same net.

SPI bus¶

spi:
  clk_pin: GPIO1
  mosi_pin: GPIO0

The display only receives data, so the bus has no MISO pin. CS, DC and RST are set on the display block.

Backlight and Display switch¶

output:
  - platform: ledc
    id: backlight_pwm
    pin: GPIO21

light:
  - platform: monochromatic
    id: backlight
    output: backlight_pwm
    internal: true
    restore_mode: ALWAYS_OFF

switch:
  - platform: template
    name: Display
    id: tft_enable
    icon: mdi:monitor
    optimistic: true
    restore_mode: RESTORE_DEFAULT_ON
    turn_on_action:
      - light.turn_on:
          id: backlight
          brightness: 100%
    turn_off_action:
      - light.turn_off: backlight

Key	What it does
`ledc` output	PWM on GPIO21 for the backlight
`light` (internal)	Drives brightness; not shown in Home Assistant
`switch` Display	On/off in Home Assistant — turns the TFT backlight fully on or off
`RESTORE_DEFAULT_ON`	Remembers the last Display state; defaults to on

Readings keep updating while the backlight is off.

Fonts and QR¶

font:
  - file: "gfonts://Roboto@500"
    id: font_big
    size: 36
  - file: "gfonts://Roboto"
    id: font_text
    size: 18
  - file: "gfonts://Roboto"
    id: font_small
    size: 14
  - file: "https://raw.githubusercontent.com/Templarian/MaterialDesign-Webfont/master/fonts/materialdesignicons-webfont.ttf"
    id: font_mdi
    size: 26
    glyphs:
      - "\U000F0432"  # qrcode
      - "\U000F0C90"  # ip-network-outline
      - "\U000F05AA"  # wifi-off
      - "\U000F091F"  # wifi-strength-1
      - "\U000F0922"  # wifi-strength-2
      - "\U000F0925"  # wifi-strength-3
      - "\U000F0928"  # wifi-strength-4
      - "\U000F0379"  # monitor
      - "\U000F06E8"  # lightbulb-on
      - "\U000F0336"  # lightbulb-outline
  - file: "https://raw.githubusercontent.com/Templarian/MaterialDesign-Webfont/master/fonts/materialdesignicons-webfont.ttf"
    id: font_mdi_lg
    size: 40
    glyphs:
      - "\U000F05A8"  # white-balance-sunny

qr_code:
  - id: setup_qr
    value: "WIFI:S:${ap_ssid};T:WPA;P:${ap_password};;"

Piece	Role
`font_big` (36)	The lux value
`font_text` (18)	Mode, SSID and IP
`font_small` (14)	`lx` and the dBm reading
`font_mdi` (26)	Status row, LED bulb, monitor, QR
`font_mdi_lg` (40)	Large sun above the lux reading
`setup_qr`	Standard Wi‑Fi QR from the same `ap_ssid` / `ap_password` as the hotspot

Only the glyphs listed are embedded, which keeps the firmware small. Roboto and the icon font are downloaded at compile time (needs internet once), then baked into the firmware.

Pages¶

page_setup draws the SoftAP QR. page_run is the connected dashboard — Wi‑Fi strength, live lux, mode label, LED on/off, IP, and a monitor icon for the Display switch. Full lambdas live in firmware/lux.yaml.

Setting	What it does
`update_interval: 2s`	Redraw every two seconds
`invert_colors: true`	Matches this 240×240 module — flip if colours look wrong
First page in the list	Default is readings; boot logic shows QR only when no home Wi‑Fi is saved
`wifi_info` text sensors	Feed SSID and IP into `page_run`
`wifi_signal`	Feeds dBm and picks the strength icon

Page	Draws
`page_setup`	QR icon, "Scan to set up", SoftAP QR, hotspot name (`Lux Setup`)
`page_run`	Wi‑Fi strength + SSID + dBm; sun icon + lux + `lx`; mode (`Off` / `Schedule` / `Night`) + LED bulb; IP + display-on icon

The monitor icon is always drawn. It does not change when you switch Display off — the backlight is off by then and the whole screen is dark.

Wi‑Fi setup chooses the page at boot and on connect / disconnect (QR only when unprovisioned).

When you change the run-page layout, keep this page and the mock-up in sync.

Next: Factory reset