GPay and TWRP: NFC payment not possible / forbidden

After flashing my old Samsung smartphone to TWRP (s. this posting) and before installing a custom OS, i did some tests with the original Android OS.
Everything worked but GPay refuses to work:

Your Phone can't make contactless payments
Check your phone software to see if it meets standards
Check software"
and the button "Check software" opens this popup:

Your phone doesn't meet software standards

You can't make contactless payments with this device. It may be rooted or running uncertified software. Contact your device manufacturer or visit Google Pay Help for more info.You can still use Google Pay to pay online.
So GPay does not only check the OS - it checks the bootloader, too.
Even if you did not rooting/jailbreaking your OS...


My Nexus 7 (2012) is online again (with lineageos and external battery)

In 2014 i did the last update for my Nexus 7 (s. here).
It was the last update which was provided by Google for this device:
I bought the Nexus 7 seven and a half year ago and on the weekend i found the tablet in the back of the cupboard. It did not work, because the battery was completely discharged and the device refused to charge it.
Without a battery it is not possible to startup the device - only power over USB is not enough.

So i disassembled it like described here and added some cables to connect a battery from outside:

And with that modification i was able to start it  - but running Android 5 with 8GB disk space is no fun.
So i booted TWRP onto this device:

root@zerberus:~/bin# fastboot oem unlock
                                                   (bootloader) erasing userdata...
(bootloader) erasing userdata done
(bootloader) erasing cache...
(bootloader) erasing cache done
(bootloader) unlocking...
(bootloader) Bootloader is unlocked now.
OKAY [193.432s]
Finished. Total time: 193.433s

root@zerberus:~/bin#fastboot boot  ~/Downloads/twrp-3.0.2-0-grouper.img
After that i was able to install lineageOS via adb sideload.

 adb sideload  ~/Downloads/lineage-14.1-20171122_224807-UNOFFICIAL-aaopt-grouper.zip 
 adb sideload  ~/Downloads/open_gapps-arm-7.1-pico-20200415.zip 
Now the device has nearly 6GB space left:

 I can use the play store and the device runs on Android version 7 - and it runs youtube movies without any interruptions...


Using a video capture usb stick with Linux / Ubuntu

Three weeks ago i ordered a video capture usb stick at banggood and today it arrived:

So will this device work with my ubuntu?

I inserted the stick on my laptop and dmesg showed:

[123483.143071] hid-generic 0003:534D:0021.0002: hiddev0,hidraw1: USB HID v1.10 Device [MACROSILICON AV TO USB2.0] on usb-0000:00:14.0-1/input4

That was all...
But there was a module missing:

modprobe uvcvideo
and after that:
[125822.751366] usb 1-1: new high-speed USB device number 19 using xhci_hcd
[125822.901442] usb 1-1: New USB device found, idVendor=534d, idProduct=0021
[125822.901449] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[125822.901454] usb 1-1: Product: AV TO USB2.0
[125822.901458] usb 1-1: Manufacturer: MACROSILICON
[125822.901478] usb 1-1: SerialNumber: 20150130
[125822.902702] uvcvideo: Found UVC 1.00 device AV TO USB2.0 (534d:0021)
[125822.902835] uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[125822.904681] uvcvideo 1-1:1.0: Entity type for entity Processing 2 was not initialized!
[125822.904691] uvcvideo 1-1:1.0: Entity type for entity Camera 1 was not initialized!
[125822.911070] hid-generic 0003:534D:0021.0004: hiddev0,hidraw1: USB HID v1.10 Device [MACROSILICON AV TO USB2.0] on usb-0000:00:14.0-1/input4
Checking with
root@zerberus:~# ffmpeg -sources |grep video
Auto-detected sources for video4linux2,v4l2:
  /dev/video1 [AV TO USB2.0]
  /dev/video0 [HD WebCam: HD WebCam]
root@zerberus:~#  ffmpeg -list_formats all -i /dev/video1

[video4linux2,v4l2 @ 0x55b0d1ca38c0] Compressed:       mjpeg :          Motion-JPEG : 480x320 640x480 720x480
[video4linux2,v4l2 @ 0x55b0d1ca38c0] Raw       :     yuyv422 :           YUYV 4:2:2 : 480x320
/dev/video1: Immediate exit requested

Now i was able to open /dev/video1 with VLC:

The video came from a camera connected via TS832 --[5.8GHz]--> RC832...


Smartphone: Installing lineageOS + Googles Play Store (and getting 9GB system space freed up)

After installing TWRP as bootloader i was wondering, how much effort is is to install an alternative to android on my old smartphone.

Heimdall & ADB were in place (see TWRP posting) - so let's start!

I downloaded the appropriate image from https://lineageos.org/ and i did the following on my smartphone:
Click on "Wipe"
 Click on "Format Data"
 Type "Yes"
 Step two times back and click "advanced wipe"
Choose "Cache" and "System" and swipe to the left

Step back to home screen and choose "Advanced"

 Choose ADB sideload & Swipe to the left

and then type:

sudo ./adb sideload ~/Downloads/lineage-16.0-20200325-nightly-a3xelte-signed.zip 

[sudo] password for schroff: 

Total xfer: 1.02x                                                                                  
and then REBOOT...
(if you want a clean lineage OS)

If you want the google play store, then go to https://opengapps.org/

Download the appropriate package (i chose "pico" - https://github.com/opengapps/opengapps/wiki/Package-Comparison)

Then repeat the steps on TWRP (smartphone) for sideloading and type

sudo ./adb sideload ~/Downloads/open_gapps-arm-9.0-pico-20200403.zip

Total xfer: 1.43x                      

And after that the smartphone starts up with lineage OS and play store (To avoid problems: do not connect to mobile networks neither wifi within the startup wizard - this can result in a black screen and the wizard will never end).
The best thing: with Samsungs stock Android about 13GB was blocked by the system. Now only 4GB from 16GB are used. So i got additional 9GB free space. Really cool!


Using a custom bootloader for my smartphone: TWRP on Samsung Galaxy A3

I read about /e/ some days ago and i decided to install this on my old smartphone (a samsung A3).

So first: What is /e/?
So i started at

where i learned, that i have to install a custom bootloader on my smartphone. This is very good explained at /e/:

(You will find there the description how to install "heimdall" and "adb")

schroff@zerberus:~/bin$ sudo ./heimdall flash --verbose --RECOVERY ~/Downloads/twrp-3.3.0-0-a3xelte.img --no-reboot
Heimdall v1.4.2

Copyright (c) 2010-2017 Benjamin Dobell, Glass Echidna

This software is provided free of charge. Copying and redistribution is

If you appreciate this software and you would like to support future
development please consider donating:

Initialising connection...
Detecting device...
      Manufacturer: "SAMSUNG"
           Product: "Gadget Serial"

            length: 18
      device class: 2
               S/N: 0
           VID:PID: 04E8:685D
         bcdDevice: 021B
   iMan:iProd:iSer: 1:2:0
          nb confs: 1

interface[0].altsetting[0]: num endpoints = 1
   Class.SubClass.Protocol: 02.02.01
       endpoint[0].address: 83
           max packet size: 0010
          polling interval: 09

interface[1].altsetting[0]: num endpoints = 2
   Class.SubClass.Protocol: 0A.00.00
       endpoint[0].address: 81
           max packet size: 0200
          polling interval: 00
       endpoint[1].address: 02
           max packet size: 0200
          polling interval: 00
Claiming interface...
Setting up interface...

Initialising protocol...
Protocol initialisation successful.

Beginning session...

Some devices may take up to 2 minutes to respond.
Please be patient!

Session begun.

Downloading device's PIT file...
WARNING: Empty bulk transfer after receiving packet failed. Continuing anyway...
PIT file download successful.

Uploading RECOVERY
0%ERROR: Failed to unpack received packet.

ERROR: Failed to receive file part response!
RECOVERY upload successful

Ending session...
Releasing device interface...
and then:
For more information take a look at https://twrp.me/