Topic: How to debug input signal

Hi All,

I believe I am feeding my NeTV a 720p input signal but I am getting the "demo box" in the bottom right of screen for a second or 2 and then it goes to rainbow static/fuzz. I am still able to see the video image in the background...

Is there a way to debug this over ssh? For instance, is there a way to tell what the NeTV thinks the input signal is?

Thanks for any assistance!

Re: How to debug input signal

Hi robotkad,

I know next to nothing about the NeTV's video hardware but maybe this would work to give you info about the input resolution. I found this wiki page and this Ubuntu manual page, neither of which has anything to do specifically with the NeTV but gave me a starting point to experiment.

Connect to your NeTV via SSH and type these three commands:

cat /sys/class/graphics/fb0/modes
cat /sys/class/graphics/fb0/virtual_size
fbset

When I have my Roku (input source) set for 720p and connected to my NeTV, I get:

root@localhost:/# cat /sys/class/graphics/fb0/modes
U:1280x720p-10
U:1280x720p-10
root@localhost:/# cat /sys/class/graphics/fb0/virtual_size
1280,720
root@localhost:/# fbset

mode "1280x720-11"
        # D: 13.481 MHz, H: 8.171 kHz, V: 10.894 Hz
        geometry 1280 720 1280 720 16
        timings 74176 110 220 20 5 40 5
        accel false
        rgba 5/11,6/5,5/0,0/0
endmode

When I have my Raspberry Pi set for 1080i and connected to my NeTV, I get:

root@localhost:~# cat /sys/class/graphics/fb0/modes
U:1920x1080i-11
U:1280x720p-10
U:1280x720p-10
U:1280x720p-10
root@localhost:~# cat /sys/class/graphics/fb0/virtual_size
1920,1080
root@localhost:~# fbset

mode "1920x1080-6"
        # D: 13.481 MHz, H: 6.128 kHz, V: 5.561 Hz
        geometry 1920 1080 1920 1080 16
        timings 74176 92 148 2 16 40 4
        accel false
        rgba 5/11,6/5,5/0,0/0
endmode

In both the Roku and Raspberry Pi setups, I was able to obtain my Panasonic monitor's EDID info by running the following command. It gives a lot of output so I'm editing it down for brevity. It doesn't seem to show the current input resolution that you're looking for so I'm just mentioning the customize_edid command for what it's worth.

root@localhost:~# customize_edid 
(null): EDID checksum passed.

        # EDID version 1 revision 3
Section "Monitor"
        # Block type: 2:0 3:fe
        # Block type: 2:0 3:fc
        Identifier "chumby NeTV  "
        VendorName "CHM"
        ModelName "chumby NeTV  "
        # Block type: 2:0 3:fe
        # Block type: 2:0 3:fc
        # Block type: 2:0 3:fd
        HorizSync 26-46
        VertRefresh 23-60
        # Max dot clock (video bandwidth) 80 MHz
        # DPMS capabilities: Active off:no  Suspend:no  Standby:no
....
EndSection
....
Section "Monitor"
        # Block type: 2:0 3:fc
        Identifier "Panasonic-TV"
        VendorName "MEI"
        ModelName "Panasonic-TV"
        # Block type: 2:0 3:fc
        # Block type: 2:0 3:fd
        HorizSync 15-68
        VertRefresh 23-61
        # Max dot clock (video bandwidth) 150 MHz
        # DPMS capabilities: Active off:no  Suspend:no  Standby:no

        Mode    "1920x1080"     # vfreq 60.000Hz, hfreq 67.500kHz
                DotClock        148.500000
                HTimings        1920 2008 2052 2200
                VTimings        1080 1084 1089 1125
                Flags   "+HSync" "+VSync"
        EndMode
        Mode    "1920x540"      # vfreq 60.053Hz, hfreq 33.750kHz
                DotClock        74.250000
                HTimings        1920 2008 2052 2200
                VTimings        540 542 547 562
                Flags   "Interlace" "+HSync" "+VSync"
        EndMode
        # Block type: 2:0 3:fc
        # Block type: 2:0 3:fd
EndSection
....

This NeTV specific blog post has more chip-level tech info (way over my head). At the start of the post you'll see a reference to the fpga_ctl command which seems to be able to manipulate or view video settings. Somewhere I got the impression that you should only use the "write" or "set" arguments if you know what you're doing, and that's definitely not me!

3 (edited by robotkad 2015-06-29 08:04:30)

Re: How to debug input signal

Thanks Taa, some very solid info here.