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I'm looking for a way to disable and enable the phone's touchscreen via console, and possibly the physical buttons, so to prevent finger touches from being processed. The phone is a Samsung Galaxy Fame, Android 4.1.x.

Background:

I'm configuring an old Galaxy Fame to serve as a sat navigator fixed on my car dashboard, aiming at using the up-to-date and free OpenStreetMap.

When I turn the key, the phone's USB is powered at 5V, when I turn off the car, the USB has no power. The phone is able to detect these events and I scripted some actions upon them, aiming at providing an instant-on and instant-off navigator service.

The phone remains always on and just switches to a power-save status when the car is off. The navigator app – OsmAnd – starts automatically at boot, but the boot does not occur between a car-on / car-off cycle, because the phone remains on to detect the mentioned USB changes.

Currently, what happens when I start the car and the USB gets powered:

  • Display is lit (echo 200 >/sys/class/backlight/panel/brightness)
  • Sat receiver is activated
  • CPU frequency set to max

What happens when I turn off the car and USB loses power:

  • Display's backlight off
  • The sat receiver goes off, along with WiFi and Bluetooth, in case they might have been active
  • CPU frequency set to minimum

Up to this point, everything is working. My problem now is that, when the car goes off and the phone enters this quasi-standby mode, the touchscreen still accepts input and, if the phone is handled or touched for whatever reason, it will stealthily react to those touches while the screen is unlit.

Andrew T.
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davide
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  • what is the model id of this device? meaning sm-blahblah , also can you post your init.rc to a pastebin? You have this device rooted?, grep your ramdisk *.rc's the perms/chown entries should tsp-ish, touch screen panel – moonbutt74 Aug 16 '15 at 00:47
  • run cat /sys/class/sec/sec_touchscreen/set_module_off

    if it comes back 0 then echo it to 1 and see what happens. Also how do i wrap code in comments?

     – moonbutt74 Aug 16 '15 at 00:50
  • This is a "Samsung Galaxy Fame gt-s6810p"; /init.rc is here: https://pastebin.mozilla.org/8842877 ; the device is rooted and I can execute su; grep results look interesting but I have not yet experimented with these control files: https://pastebin.mozilla.org/8842878 . My fiddlings with /sys/class/sec/sec_touchscreen/set_module_off are here: https://pastebin.mozilla.org/8842879 – davide Aug 16 '15 at 02:13
  • okay, that's a classic mistake, it's a good thing anything you do at the moment is temporary, cat FIRST to find out if it's a 0 or 1 type of setting. – moonbutt74 Aug 16 '15 at 02:27

3 Answers3

3

cat your init.rc and under # Permissions for InputDevices.

chown system radio /sys/class/sec/tsp/cmd
chmod 0660 /sys/class/sec/tsp/input/enabled  <--your device may differ
chown system system /sys/class/sec/tsp/input/enabled <--your device may differ

Add to your scripting setup after verifying, for my device, a Samsung Galaxy Tab 4

echo 0 > /sys/class/sec/tsp/input/enabled

Touchscreen disabled.

echo 1 > /sys/class/sec/tsp/input/enabled

Touchscreen re-enabled.

Andrew T.
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moonbutt74
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  • Cool to hear! My phone however doesn't have that control file. The closest things I can approach to by grep-ping under /sys for the strings enable and tsp are: /sys/devices/virtual/sec/tsp/power/autosuspend_delay_ms — which I ignorantly overwrote to 1000, to no avail, and /sys/module/hid_prodikeys/parameters/enable, which I overwrote to N,N,N,N,N,N,N,N attempting to disable the touchkeys, to no avail. Write permissions were set before each write, and no errors prompted. I was probably deceived by the name of those control files. – davide Aug 15 '15 at 23:21
  • I also tried fiddling with /sys/class/sec/sec_touchscreen/set_module_off and /sys/module/hid_magicmouse/parameters/report_touches. – davide Aug 16 '15 at 00:18
3

I found a solution from https://android.stackexchange.com/a/193667

rm -rf /dev/input/event0

Does "delete" my touchscreen input. The other events disable/delete my other hardware buttons like volume etc. After restart of the phone, they are back. You need root / su for this.

Andrew T.
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AusGutemGrund
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0

On Google Nexus 4 (mako, LineageOS 14.1) and Xiaomi Mi5 (gemini), you can give

rm /dev/input/event2

to disable the touchscreen at runtime. You will still be able to control the device through scrcpy.

On Google Nexus 5 (hammerhead, LineageOS 14.1) you can give

rm /dev/input/event1
Andrew T.
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Scrooge McDuck
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