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 panel on or off.

Mock-up from the display code: SoftAP QR, then Wi‑Fi status, side-by-side temp / humidity tiles, IP, and a display-on cue.

Pins¶

Signal	GPIO	Set in	Wired in
SCK / SCL	12	`spi`	Display (checkpoint 4)
MOSI / SDA	11	`spi`	same
CS	10	`display`	same
DC	9	`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: GPIO12
  mosi_pin: GPIO11

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

Fonts and QR¶

font:
  - file: "gfonts://Roboto@500"
    id: font_big
    size: 36
  - file: "gfonts://Roboto"
    id: font_text
    size: 18

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

Piece	Role
`font_big` (36)	Temperature and humidity values
`font_text` (18)	Labels and SSID / IP
`font_mdi` / `font_mdi_lg`	Material Design Icons (status row + large climate icons)
`setup_qr`	Standard Wi‑Fi QR from the same `ap_ssid` / `ap_password` as the hotspot

Roboto is 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, two climate tiles (thermometer / humidity), IP, and a monitor icon that matches the Display switch when the panel is on. Full lambdas live in firmware/climate.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
`page_run`	Wi‑Fi strength + SSID + dBm; temp \| humidity tiles; IP + display-on icon

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

Next: Factory reset