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CYD LeetCode daily

~/personal/experiments/cyd/Leetcode/Leetcode.ino. Pulls LeetCode’s daily question and scrolls it on the CYD.

How it works

Section titled “How it works”
  • Fetch: POST https://leetcode.com/graphql, query questionOfToday { activeDailyCodingChallengeQuestion } → title, frontend id, difficulty, HTML body. No auth needed.
  • Sanitize: sanitizeHtml() strips tags; the body arrives as HTML.
  • Render: TFT_eSPI, setRotation(0) (portrait). Text is pre-wrapped into wrappedLines, drawn a window at a time.
  • Scroll: auto-advances one line per second, wraps at the end.
  • Touch: any touch toggles auto-scroll on/off. 300 ms debounce, no coordinate regions — the whole screen is the button.
  • Refresh: hourly (fetchInterval = 3600000).

Wiring

Section titled “Wiring”

Touch is XPT2046 on its own SPI bus, separate from the display: IRQ 36, MOSI 32, MISO 39, CLK 25, CS 33. Display pins come from TFT_eSPI’s config, not this sketch — a wrong User_Setup.h is the usual cause of a white or mirrored screen. TouchTest/ in the same folder isolates the touch side.

Gotchas

Section titled “Gotchas”
  • WiFi is a hardcoded array of SSID/password structs, tried in order with a 10 s timeout each. Adding a network means reflashing.
  • DynamicJsonDocument(8192) — a long question body will silently truncate. Failures show as JSON Error / API Error on screen; check serial for more.
  • leetcode.txt alongside is an older copy of the sketch, not a data file. The two have diverged; .ino is the real one.