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IT8951: a clear after sleep fails, the busy line stays low 2.2 s while drawing

Aperta
  • Qualcosa non va?
#104 1 commento 0 reazioni 0 assegnatari Vedi su GitHub

I maintainer di solito rispondono entro 1 giorno

@txoof-bot ci sta già lavorando.

Dal 22/10/2026.

  • #105 di @txoof-bot — aperta

Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
25/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Ferma
Stack tecnologico
python
Ambito
backend, embedded-iot

Direzione di ricerca

Start in src/epdlib/drivers/it8951/ and the related tests and docs; reproduce the clear-after-sleep failure with the pretend controller, then compare its busy-line waits with the stated timeout and ready_timeout behavior. The issue describes the intended recovery after waking, including one reset and resending settings. Done means the tests cover these behaviors and the result works on the 9.7" screen; pull request #105 is already open.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

in-progress

Found while installing PaperPi as a systemd service on the 9.7" screen (txoof/PaperPi#295).

What happens

After sleep(), a clear() fails with "screen not ready: the busy line stayed low". Measured on the 9.7": while it draws the clear (INIT) right after waking from sleep, the controller keeps the busy line low for 2.2 s, and the driver waits at most ready_timeout (2.0 s) before each transfer, also for the "still drawing?" register reads after the draw command. A clear without sleep before it stays just under 2 s, and fast writes are much shorter, so only clears after sleep fail. PaperPi sleeps after every write, so its hourly cleaning clear failed (and its first clear at start).

(A first explanation, a board stuck after an interruption, was wrong: the time is just over the limit, so it fails or works by a few hundredths of a second.)

Fix (chosen by txoof)

  • After a draw command, the wait for the busy line uses the operation's time limit (timeout, 15 s), not ready_timeout.
  • When the screen doesn't answer after waking, the driver resets it once, sends its settings (packed pixels, VCOM) again and goes on, with a warning in the log.
  • Tests with the pretend controller, docs, and runs on the 9.7".

Area

drivers/it8951 (src/epdlib/drivers/it8951/), docs.

Lingua principale
Python
Stelle
21
Fork
10
Merge medio
1h 34m
PR unite (30g)
15

Preparare l'ambiente

  • Nessun Dockerfile né file Docker Compose
  • Ha un modello di pull request
  • Nessuna guida per i contributori

Come iniziare

  1. Leggi tutta la issue e poi la guida ai contributi del progetto.
  2. Commenta sulla issue per dire che te ne occupi tu — evita che due persone facciano lo stesso lavoro.
  3. Fai un fork del repository e lavora su un branch.
  4. Apri una pull request che faccia riferimento al numero della issue.

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