Strip Down Guide for BenQ 28" VA Monitor GC2870H

yep_DD · Sep 10, 2018, 9:48 AM

@madscientist you were right, it does not work well behind the mirror. I will keep the sensor anyway as the way it is designed it is easier to affix to my aluminum frame. I am now thinking of getting small black plexiglas casing to attach to the bottom part to control the mirror and make it look nice… let’s see.

So this could be the plan:

Plexiglas with Cutout letters
behind that translucent plexiglas
glue together
LED Strip on top of translucent glas to illuminate the cutout letters
enjoy?

yep_DD · Sep 11, 2018, 12:25 PM

I am just going to follow up on that, I found a different solution. I am using a HUE Dimmer Switch that is controlled via FHEM and it controls a python script running on MagicMirror to play my podcast and change the volume:

(I found that script somewhere on github and modified it a bit)

#!/usr/bin/python3 -u

host_name = '10.0.1.49' 
host_port = 8000

import RPi.GPIO as GPIO
import os
import subprocess
import signal
from subprocess import call
from time import sleep
from http.server import BaseHTTPRequestHandler, HTTPServer




class MyServer(BaseHTTPRequestHandler):

    def do_HEAD(self):
        self.send_response(200)
        self.send_header('Content-type', 'text/html')
        self.end_headers()

    def do_GET(self):
        global proc
        html = '''
           <html>
           <body style="width:960px; margin: 20px auto;">
           <h1>Magic Mirror Control</h1>
           <p>Current GPU temperature is {}</p>
           <p>Podcast: <a href="/play">Play</a> <a href="/stop">Stop</a></p>
           <p>Volume: <a href="/down">down</a> <a href="/up">up</a></p>
           <p>System: <a href="/shutdown">Shutdown</a> <a href="/restart">Restart</a></p>
           <div id="podcast-status"></div>
           <script>
               document.getElementById("podcast-status").innerHTML="{}";
           </script>
           </body>
           </html>
        '''
        temp = os.popen("/opt/vc/bin/vcgencmd measure_temp").read()
        self.do_HEAD()
        status = ''
        if self.path=='/':
            status='nothing'
        elif self.path=='/play':
            proc = subprocess.Popen(["omxplayer", "-o", "alsa:hw:ALSA", "--no-osd", "/tmp/video.mp4"], preexec_fn=os.setsid)
            status='Playing Podcast'
        elif self.path=='/stop':
            status='Stopping Podcast'
            os.killpg(os.getpgid(proc.pid), signal.SIGTERM)
        elif self.path=='/shutdown':
            status='Shutdown'
            subprocess.Popen(["sudo", "shutdown", "-h", "now"], preexec_fn=os.setsid)
        elif self.path=='/restart':
            status='Restart'
            subprocess.Popen(["sudo", "reboot"], preexec_fn=os.setsid)
        elif self.path=='/down':
            status='Volume down'
            subprocess.Popen(["amixer", "set", "Master", "12%-"], preexec_fn=os.setsid)
        elif self.path=='/up':
            status='Volume up'
            subprocess.Popen(["amixer", "set", "Master", "12%+"], preexec_fn=os.setsid)
        self.wfile.write(html.format(temp[5:], status).encode("utf-8"))


if __name__ == '__main__':
    http_server = HTTPServer((host_name, host_port), MyServer)
    print("Server Starts - %s:%s" % (host_name, host_port))

    try:
        http_server.serve_forever()
    except KeyboardInterrupt:
        http_server.server_close()

Adrien · Oct 17, 2018, 4:44 PM

Hello,

Would it be possible to use a relay to power/unpower the screen ? On the sheet you show pin 3/4 power the backlight correct?

Thanks

MadScientist · Oct 17, 2018, 5:27 PM

@adrien check out this forum thread. cruunnerr explains different methods on how to turn on/off your screen. He helped me setting up my system which uses a relay and PIR-sensor to power on/off my LCD. I think that’s what you’re looking for.

Adrien · Oct 17, 2018, 5:58 PM

Well i’m not sure, i don’t use the magic mirror OS but home made application. I use a pir sensor, i would like to have instant poweron/poweroff without any OSD message on screen. So My question was if i cut the pin 3 or 4 on the backlight connector will it work ? To be clear when the PIR detect someone the relay connect the PIN (3 or 4) after few seconds relay disconnect the PIN (3 or 4)

MadScientist · Oct 17, 2018, 6:04 PM

@adrien That should still be possible with the script method described in 5.1. Instead of the power lines for the controller board of the LCD you use the cables that lead to your backlight.

I don’t know what LCD you have. Some have an extra inverter or LED driver board. You can take the cables from there. Some have a 40 pin LVDS cable (instead of 30 pin), so you have to check the datasheet which wires are for the backlight. I’d take the VCC wire for the backlight, snip it and connect both lose ends to the relay. That should work.

Keep in mind that with this method the LCD is always on, only the backlight is off.

Adrien · Oct 18, 2018, 4:17 AM

Thanks for your help. I use the same model :BenQGC2870H. I would like to combine a solution where i have a minimum power consumption and fast without osd message boot.

yep_DD · Oct 21, 2018, 11:39 AM

@adrien Hi Adrien, that was my initial plan but I use the two relays now for my speakers to avoid the initial crack sound when powering on the amplifier und I use one relay for the monitor power supply and one for the amplifier.

Adrien · Oct 21, 2018, 12:25 PM

@yep_dd Hello, and thanks for your guide :) Did you try to do it ? do you confirm that could work ? Thanks

yep_DD · Oct 21, 2018, 1:37 PM

@Adrien No problem, I am pretty sure it should work but I have not tried it. I might in the future. I am working on a few other bugifxes as well (amplifier only turns on when sound is played and stuff like that). I also suggest to use the microwave / radar sensor instead of the PIR. it is much cleaner and can go behind the mirror.

Regarding the OSD, instead of cutting wires to the backlight this seems like a valuable option. At the moment I can’t try this (I need a friend to help me take down the mirror as it is too heavy), but I will tomorrow: https://www.youtube.com/watch?v=y86AXOZwlgU (TL;DW: press menu button while turning monitor on and disable logo)