First I want to thank all contributor for the Magic Mirror project. I really enjoy this project to build my own mirror and learn new things.

I have a pi 3b+ running on the latest OS :
stretch V9.6

I have installed MM and followed all documentations then implemented a few modules.
the defaults one they are working fine ( some are commented such as alert and notifications (For debugging the blank screen issue I have and make sure the cause was not those modules)
MMM-AssistantMk2 & MMM-Hotword ( perfectly works )
MMM-NowPlayingOnSpotify working fine but commented for as well because getting too much errors ( when nothing was played )
mmm-systemtemperature : Works OK
MMM-DarkSkyForecast :Works OK
MMM-Hue : Works OK
MMM-Traffic : Works OK
MMM-PIR-Sensor (To turn off&on the HDMI Port) : Works OK

You will tell me all “works OK” so what’s wrong with you guy :)

Well after I start my MM all is “work ok” (Again)
The Pir sensor delay works and well shutdown the HDMI port and it comes back when a movement is detected. My delay is set to 10 mins and if I come back after 15mins the screen is back ON, So far so good .

Now my issue : When I come back after a while let’s say an hour or more, the PIR sensor turn ON the HDMI port and my screen goes on.

Then surprise I get a blank screen.

I know I’m not in screen saver mode because after a VNC connection I see the little popup on screen and I can see the mouse moving as well.

My conclusion is that the MM is in a kind of “sleep” mode waiting to be wake up.

I can bring the MM modules back on screen for example by giving input via the Hotword/assistant module so when I say “Jarvis” the hotword is detected and MM & all modules directly come back on screen.

No error in the MM error log from PM2 nor in the out file.
Dev mode ( Shift CTRL I ) show me that the modules are still well receiving notification from other modules )

Before posting this thread here as I said I read the full installation documentation and more. I did many research for a similar problem and didn’t find . I looked at many places and applied several solutions. Unfortunately without success ).

It look like it’s a matter in the MM code itself ( But I maybe wrong I do not want to bother anyone by saying this ) Just a personnal thought.

Here is my setup :
/etc/lightdm/lightdm.conf

[SeatDefaults] ( I had to create this entry in the file ) 
xserver-command=X -s 0 -dpms

As well added to

[Seat:*] ( which was existing prior editing the file )
xserver-command=X -s 0 -dpms

Just in case ( but I have added this after and that didn’t help )

The file /etc/xdg/lxsession/LXDE-pi/autostart

@pcmanfm --desktop --profile LXDE-pi
@xscreensaver -no-splash
point-rpi
@xset s noblank
@xset s off
@xset -dpms

And /etc/xdg/lxsession/LXDE/autostart

@lxpanel --profile LXDE
@pcmanfm --desktop --profile LXDE
@xscreensaver -no-splash
@xset s noblank
@xset s off
@xset -dpms

I didn’t make it in /.config/lxsession/LXDE-pi/autostart because when creating this file my system boot in openbox and not in desktop session.
And I want to keep the desktop for other reason.

I installed xscreen and turn of powersaving on screen and screen saver.

My config.js file :

/* Magic Mirror Config Sample
*
* By Michael Teeuw http://michaelteeuw.nl
* MIT Licensed.
*/
var config = {
	"port": 8080,
	"language": "fr",
	"timeFormat": 24,
	"units": "metric",
	"modules": [
//		{
//			"module": "alert"
//		},
//		{
//			"module": "updatenotification",
//			"position": "top_bar"
//		},
		{
			"module": "clock",
			"position": "top_left"
		},

/*		{
			"module": "MMM-NowPlayingOnSpotify",
			"position": "top_left",
			"config": {
				"clientID": "f---------------------------0",
				"clientSecret": "7------------------------------6",
				"accessToken": "B------------------------------------------A",
				"refreshToken": "A------------------------------------A"
			}
		},
*/
		{
			"module": "MMM-AssistantMk2",
			"position": "top_right",
			"config": {
				"record": {
					"recordProgram": "arecord",
					"device": "plughw:1"
				},
				"play": {
					"playProgram": "mpg321"
				},
				"deviceLocation": {
					"coordinates": {
						"latitude": 48.739464,
						"longitude": 2.557584
					}
				},
				"defaultProfile": "default",
				"profiles": {
					"default": {
						"profileFile": "default.json",
						"lang": "fr-FR"
					}
				},
				"responseVoice": true,
				"responseScreen": true,
				"responseAlert": true,
				"screenZoom": "80%",
				"screenDuration": 3000,
				"youtubeAutoplay": true,
				"pauseOnYoutube": false,
				"youtubePlayerVars": {
					"controls": 0,
					"loop": 1,
					"rel": 0
				},
				"youtubePlayQuality": "default",
				"verbose": false,
				"auth": {
					"keyFilePath": "./credentials.json"
				},
				"action": {},
				"transcriptionHook": {},
				"command": {},
				"notifications": {
					"ASSISTANT_ACTIVATE": "ASSISTANT_ACTIVATE",
					"ASSISTANT_DEACTIVATE": "ASSISTANT_CLEAR",
					"ASSISTANT_ACTIVATED": "HOTWORD_PAUSE",
					"ASSISTANT_DEACTIVATED": "HOTWORD_RESUME",
					"ASSISTANT_ACTION": "ASSISTANT_ACTION",
					"DEFAULT_HOOK_NOTIFICATION": "ASSISTANT_HOOK",
					"TEXT_QUERY": "ASSISTANT_QUERY",
					"SAY_TEXT": "ASSISTANT_SAY"
				}
			}
		},
		{
			"module": "MMM-Hotword",
			"config": {
				"snowboy": [
				/*	{
						"hotwords": "smartmirror",
						"file": "resources/models/smart_mirror.umdl",
						"sensitivity": "0.5"
					},
					{
						"hotwords": "snowboy",
						"file": "resources/models/snowboy.umdl",
						"sensitivity": "0.5"
					},
*/

					{
						"file": "resources/models/jarvis.umdl",
						"sensitivity": "0.6,0.60",
						"hotwords": [
							"jarvis",
							"jarvis"
						]
					}
				],
				"record": {
					"sampleRate": 16000,
					"threshold": 0.5,
					"thresholdStart": null,
					"thresholdEnd": null,
					"silence": 1,
					"verbose": false,
					"recordProgram": "arecord",
					"device": "plughw:1"
				},
				"autostart": true,
				"autorestart": true,
				"notifications": {
					"PAUSE": "HOTWORD_PAUSE",
					"RESUME": "HOTWORD_RESUME",
					"LISTENING": "HOTWORD_LISTENING",
					"SLEEPING": "HOTWORD_SLEEPING",
					"ERROR": "HOTWORD_ERROR"
				},
				"onDetected": {
					notification: function (payload) {
        				return "ASSISTANT_ACTIVATE";
      					},
      					payload: function (payload){
        				return {
                			profile: payload.hotword
					};
				}
			},
		},
},
		{
			"module": "MMM-Traffic",
			"position": "lower_third",
			"config": {
				"api_key": "A--------------------------------------------E",
				"mode": "driving",
				"origin": "my street France",
				"destination": "my street , France",
				"route_name": "De la maison au travail",
				"changeColor": true,
				"showGreen": true,
				"limitYellow": 5,
				"limitRed": 20,
				"traffic_model": "best_guess",
				"interval": 1000000
			},
			"classes": "dimmed medium"
		},

		{
			"module": "MMM-Hue",
			"position": "top_center",
			"config": {
				"bridgeip": "192.168.0.44",
				"userid": "H---------------------------------u",
				"colour": false,
				"refreshTime": "30000"
			}
		},

{
  module: "MMM-DarkSkyForecast",
  header: "Weather",
  position: "top_right",
  classes: "default everyone",
  disabled: false,
  config: {
    apikey: "4------------------------------------------5",
    latitude: "48.725610",
    longitude: "2.572350",
    updateInterval: "60",
    language: "fr",
    label_timeFormat: "k[h]",
    label_days: ["Dimanche", "Lundi", "Mardi", "Mercredi", "Jeudi", "Vendredi", "Samedi"],
    iconset: "4c",
    concise: false,
    forecastLayout: "tiled"
  }
},
         {
               module: 'MMM-PIR-Sensor',
		config: {
			"sensorPIN": "23",
			"powerSavingDelay": 600,
		}
	},

	{
		module: 'mmm-systemtemperature',
		position: 'bottom_left',	// This can be any of the regions.
		classes: 'small dimmed', // Add your own styling. Optional.
		config: {
			// See 'Configuration options' for more information.
		}
	},


		{
			"module": "newsfeed",
			"position": "bottom_bar",
			"config": {
				"feeds": [
					{
						"title": "BFMTV",
						"url": "https://www.bfmtv.com/rss/info/flux-rss/flux-toutes-les-actualites/"
					}
				],
				"showSourceTitle": true,
				"showPublishDate": true
			}
		}
	],
	"address": "localhost",
	"ipWhitelist": [
		"127.0.0.1",
		"192.168.0.21",
		"::ffff:192.168.0.23/24",
		"192.168.0.23/24"
	]
};
/*************** DO NOT EDIT THE LINE BELOW ***************/ 
if (typeof module !== 'undefined') {module.exports = config;}

Finally I’m up to date on MM and all Modules.

I didn’t use the OpenGL driver in /boot/config.txt as in was generating error in the logs, and my pi is Fan cooled So I don’t worry for now about system temp ( always around 50°C) and CPU usage ( around 40% when MM + VNC are running )

So if anyone have clue / good question to ask my to help me dig out this issue and resolve it you are most that welcome !!! I hope that this post was not too long but I wanted to give as much details as I can.

If you need any other info feel free to ask me.

Thank you again for all your work and help .