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Topics - @lex

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Cubieboard v2 Hardware (A20 Based) / DVB-T / ISDB-T International + R820T
« on: October 01, 2015, 10:15:43 pm »
Somehow i got a binary driver for the RTL2832U (2838) and built-in support for several tuners, my primary interest is on R820T for the device i have. This driver loads on kernel 3.4.103 and should work for DVB-T and ISDB-T and could be of interest for someone who could not find or build one.

I am still having problems with dvbv5-scan (version 1.01) and i am investigating.
If you have time and want to check if it works for your device, try it on DVB or ISDB (depends on where you are) and let me know.

The device:
Code: [Select]
Bus 002 Device 007: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T

Code: [Select]
Bus 002 Device 007: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x0bda Realtek Semiconductor Corp.
  idProduct          0x2838 RTL2838 DVB-T
  bcdDevice            1.00
  iManufacturer           1 Realtek
  iProduct                2 RTL2838UHIDIR
  iSerial                 3 00000001
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           34
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          4 USB2.0-Bulk&Iso
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              5 Bulk-In, Interface
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              5 Bulk-In, Interface
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  bNumConfigurations      2
Device Status:     0x0000
  (Bus Powered)

Here is the kernel log showing it was detected:
[   16.012938] usbcore: registered new interface driver dvb_usb_rtl28xxu
[   17.904270] usbcore: registered new interface driver dvb_usb_rtl2832u
[  196.940438] dvb-usb: found a 'RTL2832U DVB-T USB DEVICE' in warm state.
[  196.948248] dvb-usb: will pass the complete MPEG2 transport stream to the software demuxer.
[  196.955714] DVB: registering new adapter (RTL2832U DVB-T USB DEVICE)
[  197.930847] DVB: registering adapter 0 frontend 0 (Realtek DVB-T RTL2832)...
[  197.941424] input: IR-receiver inside an USB DVB receiver as /devices/platform/sw-ehci.1/usb2/2-1/2-1.1/input/input6
[  197.947317] dvb-usb: schedule remote query interval to 287 msecs.
[  197.961007] dvb-usb: RTL2832U DVB-T USB DEVICE successfully initialized and connected.

Steps to get it loaded

a) You should load the following modules, manually or editing /etc/modules and adding

b) Kernel must be 3.4.103 and dvb-core and dvb-usb must be enabled

c) Your Modules loaded in memory would look like this
Module                  Size  Used by
disp_ump                 861  0
ppdev                   7982  0
lp                      8121  0
parport                34531  2 lp,ppdev
dvb_usb_rtl2832u      395360  0
dvb_usb_rtl28xxu       10637  0
rtl2830                 6751  1 dvb_usb_rtl28xxu
dvb_usb                17560  2 dvb_usb_rtl2832u,dvb_usb_rtl28xxu
dvb_core               92100  1 dvb_usb
rc_core                21139  2 dvb_usb_rtl28xxu,dvb_usb
sunxi_ir                3684  0
leds_sunxi              3721  0
gpio_sunxi              8910  0
sunxi_ts               20294  0
rfcomm                 58145  0
bnep                   14129  2
bluetooth             264397  10 bnep,rfcomm
sunxi_cedar_mod         9962  0
mali_drm                2608  1
drm                   208790  2 mali_drm
mali                  111115  0
ump                    51991  4 mali,disp_ump
lcd                     3778  0

d) Install the dvb-tools

The binary driver is here:

Download and decompress it to /lib/modules/3.4.103/kernel/drivers/media/dvb/dvb-usb
Boot, attach your device and see if it gets recognized.

I hope this can be useful.

Cubieboard v2 Hardware (A20 Based) / Active Buzzer module [ Works ]
« on: September 12, 2015, 10:10:12 pm »
I have 2 Active Buzzer modules for Arduino (different makers) i want to drive with Cubieboard 2 that works with 3.3v (3v ~ 5v), but i face a hard time determining if it is safe or not to use it.

It is a module with 3 pins, vcc (3v ~5v), gnd and i/o, very simple to use, you just activate the buzzer when the i/o pin is 0v.

I have tested it on my CB2 and it works using vcc with 3.3v and using an output with 0v value Beeps the buzzer. Simple as that.

The question is when feeding VCC with 3.3v the I/O pin of the module outputs 3.6v ~ 4v (measured from GND to the I/O and it has a lot of fluctuations), and when kernel starts it usually puts the GPIO pins in INPUT mode before the GPIO module setup the PIN as output, that could happens in a very short Delta time. (Don't know about the u-boot).

Using the buzzer module while the board is already running has not damaged the output pin but i have not tested it when the board is turned on and the buzzer is plugged in.

Can you Help or elaborate about this worries?

Off-Topic Discussion / New Quad-core pin-pin compatible to A20
« on: August 31, 2015, 07:22:24 pm »
I have seen some speculation about a new quad-core pin to pin compatible with A20.

I wonder if Cubietech will release a CB2-QUAD or CB4 or CB40 and with very attractive price so we can apply all we have learnt so far to this new possible board, what you guys think?

Cubieboard v2 Hardware (A20 Based) / Wiring ov7670 module [ Solved ]
« on: July 26, 2015, 06:33:48 pm »
Hi there,

I would like to work with the OV7670 camera module on my CB2, can somebody please help on how to wire it to CB2?

Camera                  CB2
Pins                       Pins
VCC  ->
GND ->

SIO_C ->
SIO_O ->
D0 ->
D1 ->
D2 ->
D3 ->
D4 ->
D5 ->
D6 ->
D7 ->

I will work with kernel 3.4.103.
Appreciate if you could help.


Cubieboard v2 Hardware (A20 Based) / GPIO with a switch button
« on: July 21, 2015, 10:47:13 am »

I would like to have a switch button connected directly to a GPIO input pin, but reading the forum i am not sure if it is safe or not.

I have already setup the board CB2 and CB1 with GPIO sysfs and it is working fine, input and output, just followed instructions, piece of cake.

Now i want to make sure i do it right without burning everything, can someone with experience in hardware give some answer?:

- Is it safe to connect a switch directly on input pin? I will use a button (push button) and reed switch.

- Setting the input pin for the button/switch, should be 1 = pullup enabled; 2 = pulldown enabled ?

- I've read Lawrence post about input pin should have a 10k resistor or other value depending which pin.
Is this to protect from high current or to prevent fluctuation?

GPIO has been extensively discussed here in the forum but most of the time is output gpio.

I would appreciate if someone could answer those question.


Cubieboard v2 Hardware (A20 Based) / GPIO and LED
« on: April 20, 2015, 09:04:36 pm »

I started working on GPIO today and i think i burned the blue LED somehow.

I have GPIO and LEDS as a module and had the heartbeat running on blue LED but after i played with GPIO on blue LED it stopped lighting, no more sign of life for this LED.

I cannot remember the exact sequence of commands i typed, but i think i set it to input and later to output and vice-versa, just to experiment if was working.

The odd thing is that i cannot use the same GPIO port when the LEDS are set on FEX in Android, kernel complains and warn the port is already in use. This does not happen in linux when both are loaded as modules.

What are the chances to burn the LEDs using GPIO?



Projects / LVDS 18.4" with Touch Screen (resistive) - FULL HD
« on: January 18, 2015, 06:22:26 pm »

This is a project i started working, which has  a 18.4" LCD panel with Resistive touch and Full HD (1920x1080), pushing the CB2 and allwinner A20 to its limits.

There are some issues i am working on.

I would like to thanks George Ioakimedes for helping with the LCD Panel and finding the correct timings.

I will get this working with X-Org and share my findings if i can.

Here is the woking in progress:


** sorry, this should go into Cubieboard 2 **

Long ago i tried to boot Android in portrait mode in HDMI with reasonable results, unfortunately i did not take notes on what was done and accidentally i got a nice feature that was: when i clicked in
  • Rotate screen (introduced in v1.6 by James), the screen rotated 90 degrees on the fly, so it run any apps in portrait mode, no need to change anything or run any additional apps, just like i wanted.

With v1.9 it does not work anymore for some reason, or it needs some Apps to make it work that way, perhaps i had installed some apps and can not remember.

Anyway, i need a way to use a small keyboard (keypad) to have BACK and FORWARD push buttons to switch to other Apps or end  the Apps that needs push button like video, etc..?

I have a Membrane 1x4 Keypad  which i would like to use, so what free GPIO pins i could use for the Android 4.2 and how i should change sys_config to get access to this pins?

Anyone already did that?

Here is the work in pogress for the portrait mode:


Cubieboard v1 OS (A10 Based) / A10 - Ubuntu 14.04 server with Lxde
« on: June 22, 2014, 12:33:01 pm »
I have built the ubuntu 14.04 server image for my 16 GB SD card with success, now i would like to boot it with lxde, i have tried several times to install lxde the ubuntu way but lightgdm fails to start and i have my serial debugging console locked (cannot type anything) and a message telling me on the hdmi console it will try to login in 60 secs, and again, and again...

Anyone have had success build lxde ubuntu 14.04 on A10?

*** update:
I am facing the following error, 'unable to autolaunch a dbus-daemon without $DISPLAY for X11'
what is missing here?

Off-Topic Discussion / Ubuntu Tablet - CB2
« on: April 18, 2014, 07:05:33 pm »
I have seen Ubuntu Tablet videos and seems very nice and fast.
Is it possible to run it in CB2? If yes, anyone tried it?

General Discussion / U-boot latest version
« on: April 14, 2014, 11:08:46 am »

I had the latest u-boot-sunxi, and it was compiling and working fine from inside SDK, and i had the brilliant idea and did a 'git pull', it updated some files and now i cannot build it anymore.
It now complains:  No rule to make target `cubieboard_config'

I tried to revert using: git reset --hard HEAD^1

It did not revert.

Could someone help?

Cubieboard v1 Images (A10 Based) / Qbee-X A10 error
« on: April 12, 2014, 04:55:10 pm »
I am trying to boot Qbee-X and i get the following kernel error (attached), can you help?

My uEnv.txt
extraargs=console=ttyS0,115200 disp.screen0_output_mode=EDID:1920x1080p60 disp.screen0_output_type=3 consoleblank=0 rootwait


Cubieboard v1 OS (A10 Based) / Changing partition number in NAND (A10)
« on: April 09, 2014, 06:26:25 pm »
Is it possible to change the partition number from 6 to 3 (NAND)?
We would have:
1 - bootloader
2 - env
3 - rootfs (bigger size)

And then... why the other 3 partitions? any special requirement?

Cubieboard v1 OS (A10 Based) / sun4i_config for kernel 3.4.79+
« on: April 02, 2014, 06:43:01 pm »

Can someone share your sun4i_config or cubieboard_config for kernel 3.4.79?

I am having some issues with i2c on CB1.


Cubieboard v1 OS (A10 Based) / partition schema
« on: March 30, 2014, 05:40:36 pm »
Is it possible to have this particular partition schema on CB1?

/dev/nandc       /
/dev/nandd      /tmp
/dev/nande      /var
/dev/nandf      /usr
/dev/nandg     /usr/local
/dev/nandh     /home

If yes, how can i achieve it? And how to calculate the exact partition size in bytes, just like the 1048576 = 1 GB displayed as 993 MB?

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