MMM-PresenceScreenControl — two new releases (ecoMode + Notification API)
Dear all
a small but meaningful round of updates for MMM-PresenceScreenControl just landed on main. Both started from a single GitHub issue, so I thought I’d write up the chain of reasoning rather than just drop a changelog — maybe useful for anyone evaluating a migration from MMM-Pir, and definitely useful as a reminder to myself to check the parent project’s feature surface more carefully when forking.
Part 1 — ecoMode (Issue #5)
Rocket78 opened issue #5 with a really well-argued request: even with the screen physically off, Electron keeps repainting hidden DOM. On a Pi 3 with X11, MMM-PresenceScreenControl was leaving things like Newsfeed cross-fades running every 20 seconds — and those repaints showed up clearly as CPU spikes in his graph. He asked for an equivalent of MMM-Pir’s ecoMode, which hides every other module while the screen is off, so the browser skips layout/paint/composite for them.
So I built it, but tried to keep it lean:
ecoMode: false, // opt-in, default off → no surprise
ecoModeIgnore: [] // module names to keep visible
Implementation notes that might interest other module authors:
Rocket78 also dropped a great ddcutil snippet in the issue for monitors that show a “no signal” splash when the video output is cut — that splash is genuinely immersion-breaking, and ddcutil setvcp D6 sends the actual DDC/CI power command, which is much closer to pressing the hardware power button:
onCommand: ddcutil setvcp D6 1 --skip-ddc-checks
offCommand: ddcutil setvcp D6 5 --skip-ddc-checks
Added to the README’s offCommand examples. The --skip-ddc-checks is needed because some monitors stop responding to DDC queries when powered off but still process incoming power-on commands — so the check would fail before the command is even sent.
→ Issue #5 closed, commit 42b68a6.
Part 2 — what else did I miss?
Closing the issue could have been the end of it. But Rocket78’s request raised an uncomfortable question: I never used ecoMode in MMM-Pir myself, so I didn’t notice it was missing. What else did I overlook when reviving MMM-Pir?
Three items jumped out as actual gaps that other modules in the ecosystem could legitimately depend on:
MMM_PIR-USER_PRESENCE — MMM-Pir broadcasts this notification on presence transitions. Other modules (Remote-Control, voice assistants, smart-home bridges) can listen for it.
MMM_PIR-WAKEUP / LOCK / UNLOCK / END — incoming notifications that let other modules control the screen logic externally.
MMM_PIR-SCREEN_POWERSTATUS — broadcast when the physical screen turns on or off.
Without these, anyone migrating from MMM-Pir to my fork would suddenly find their automations dead — because they’d be listening for MMM_PIR-USER_PRESENCE and nothing was coming through. Even worse, they wouldn’t know why it stopped working; the screen-on/off behavior would seem fine, but cross-module integration would be silently broken.
So I built a parallel notification API, namespaced MMM_PSC-* rather than impersonating MMM-Pir’s MMM_PIR-*:
Outgoing notifications — emitted on state transitions only:
MMM_PSC-USER_PRESENCE payload: true / false
fires when combined presence changes
MMM_PSC-SCREEN_POWERSTATUS payload: true / false
fires when physical screen turns on/off
Both fire only on actual transitions — no spam every poll cycle.
Incoming notifications — consumed by the module
MMM_PSC-WAKEUP wake screen, reset timer (equivalent to a touch)
MMM_PSC-END force screen off immediately
MMM_PSC-LOCK freeze presence handling — sensors are still tracked internally, but no longer change screen state
MMM_PSC-UNLOCK resume normal presence handling and re-evaluate the current sensor state
Implementation detail worth flagging: the LOCK guard sits in updatePresence(), which is the single funnel through which all sensor inputs (PIR, MQTT, touch, external wakeup socket) eventually pass. So whatever the trigger source, it’s correctly suppressed while locked. UNLOCK calls updatePresence() again, which re-evaluates the current sensor state — so if you’ve unlocked while a person is still in front of the PIR, the screen comes back on immediately. No need for the caller to send a WAKEUP after UNLOCK.
Useful patterns this enables:
// Wake the mirror when a doorbell event arrives:
this.sendNotification("MMM_PSC-WAKEUP");
// Force-off cleanly from outside (smart-home rule, etc.) without
// bypassing the module and going straight to the screen command:
this.sendNotification("MMM_PSC-END");
// Take exclusive control of the display for a video call,
// then hand it back when done:
this.sendNotification("MMM_PSC-LOCK");
// ... your module is showing its full-screen content ...
this.sendNotification("MMM_PSC-UNLOCK");
END is the clean way to force-off the screen from outside without touching offCommand directly — the module’s internal state stays consistent, all the right outgoing notifications still fire, and any other listeners (logging, analytics, smart home) see the transition.
Tested live end-to-end via MMM-Remote-Control’s notification API:
curl -X GET "http://localhost:8080/api/notification/MMM_PSC-LOCK"
curl -X GET "http://localhost:8080/api/notification/MMM_PSC-END"
→ screen off, stays off
curl -X GET "http://localhost:8080/api/notification/MMM_PSC-WAKEUP"
→ ignored (locked)
curl -X GET "http://localhost:8080/api/notification/MMM_PSC-UNLOCK"
→ screen back on
All four routes verified, log trace clean, outgoing notifications fired in the right order on every transition.
→ Commit 10000ca.
Update / install
If you’re already on the module:
cd ~/MagicMirror/modules/MMM-PresenceScreenControl
rm -rf node_modules
git pull
npm install
Both changes are backwards-compatible. ecoMode is opt-in (default false), and the new notifications are additive — nothing existing is modified. So you can update without touching your config and pick up only what you need.
A genuine thank-you to Rocket78 for the well-reasoned issue and the ddcutil tip — it triggered the full audit, which in turn closed a much bigger latent gap.
Exactly the kind of feedback that improves a fork. If you’ve migrated from MMM-Pir and notice anything else missing that you’d consider load-bearing, please open an issue.
Hope you find it useful.
Warmest regards,
Ralf
