A Single Board Computer From A TV

It is an annoyance for some members of our community, that it has become almost impossible to buy a TV that’s not a so-called “smart” TV. These units contain a computer as well as the display, and it boots into a locked-down OS with a user interface and a load of streaming apps. Can anything be done with them other than what their manufacturers intended? [Nina Kalinina] has managed it, taking the mainboard from a discarded LCD TV and liberating the ARM Linux board within.

On the board are all the inputs you’d expect from a TV, along with Ethernet, and a couple of extra USB ports hidden in the WiFi interface. There’s a UART available on the SCART connector, and accessing the U-boot menu is achieved by the unusual means of sending a character to the infrared port using a Palm Pilot. Surprisingly the device tree in the Flash was editable, so with the Linux OS accessed, the board was revealed as having a dual-core Novatek SoC.

This is reminiscent of the days when the new hotness was dragging a Linux box out of a home router, and just as those were quickly eclipsed by inexpensive boards such as the Raspberry Pi, so might these TV boards meet the same fate. If, however, they can be made to drive a screen with something more useful than the TV interface then that might change, as who wouldn’t want to make an old smart TV a bit more useful?

37 thoughts on “A Single Board Computer From A TV

  1. “This is reminiscent of the days when the new hotness was dragging a Linux box out of a home router, and just as those were quickly eclipsed by inexpensive boards such as the Raspberry Pi”

    And if the Pi & friends continue to be unobtainium (without sacrificing some human limbs to the fab gods) we’re obviously headed back in that direction, for better or worse.

    That said, with all the spyware they supposedly contain & the fact that ATSC-3 TVs talk back to the transmitter by RF, maybe checking out the contents of these blobs is a good white hat idea for the betterment of everyone!

    1. ATSC3.0 does not infact use RF for bidirectional communication other than wifi to the internet. The logistics of even setting that up are nearly impossible. It would require a very powerful transmitter at each endpoint (tv tuner), especially in rural areas. ATSC3.0 as written and implemented in some areas already, is a hybrid OTA/Internet solution.

      Yes, some things won’t work without talking back to the mothership via your internet connection, but it is not a RF solution as you described.

  2. While scavenging parts from TVs I always wonder about couple of ideas:
    1. Are scaler chips flexible enough to repurpose for DIY projects i.e. workbench universal unknown LCD displays reverse engineering kit?
    2. That boards appears to me as ideal platform for SDR projects, aren’t they? Maybe it’s time for sharing experiences with various platforms, something like OpenWRT initiative.
    3. Various A/V I/O ports, hardware codecs, DSPs even with genuine Dolby, DTS et consortes capabilities gives opportunity for another multi platform project focused on audio/video applications alternative to beefy studio kit, but enough for web stream authoring, surveillance, machine vision etc.

    1. 1. Probably? Most of these chips are designed for a large range of configurations – particularly useful if you want to have a range of chips that can manage from small portables to TVs with very large pixel count. (Design the peripheral once, use it on lots of different chips) Still – there may be some compromises to be made, particularly on the lower end. Getting access to tell the output what resolution you want may be the limiting factor.
      2. Not so much for SDR. The RTL2832 is and exception to the rule, it can also do sampling. It’s an exception to the rule. Most of the demodulator chips (And a good percentage of those will be built into the SoC itself) will be specifically designed for taking in DVB, ATSC, ISBT or whatever your digital standard is and piping it to an engine that can decode it with little or no intervention by the CPU. (Possibly via some sort of decrypting DMA engine) You’ll usually also have some means of getting analogue video sent to the video output.
      3. DSPs will usually be there – but they’ll mostly be transparent. Just black boxes you can send data to for decode. (I worked with one SoC that had an option of using the audio DSP to decompressing gifs instead of doing the Dolby Digital or DTS)

    2. Because of 2)
      In the past, I’ve been using old Blu-Ray Players and Smart TVs running Android (pre Android 12) for that purpose. The SDR Touch software runs on them, too. I just added an USB keyboard/mouse to turn these devices into little “PCs”. With an optional driver, the software can use RTL SDRs also.

    3. If you want something to repurpose for SDR, look at those very cheap DVR boards they sell for cheap at Aliexpress (search “dvr board” there). They all run Linux and all have very fast ADCs, especially the AHD capable ones. The downside is that their firmware is tight closed, of course (and very insecure), therefore some good hacking is needed. Liberating them would open a lot of possibilities for other purposes too since they also have HDMI, Ethernet, SATA, USB, some also RS422, etc.

  3. I recently ripped out the motherboard of a relatively new model of a Samsung 4K monitor – it’s not a smart TV, but getting some of the peripherals working (jog button, IR) as inputs has been a piece of cake. What piques my curiosity, however, is the Samsung MagicColor chip that controls the board. It handles several AV interfaces, USB, and a proprietary control port for testing and repair.

    It would take some serious effort to get my hands on a datasheet, let alone a manual, but I believe it’s capable of quite a bit, as it’s the same chip (and board with fewer ICs on the bus) used in several of Samsung’s high-end televisions. Any Samsung engineer’s out there wanna throw me a bone? ;)

    (I jest, of course)

  4. It is not surprising at all a Palm Pilot would be able to communicate with a smart TV. The split up and recombination of Palm eliminated the original Palm OS. WEB OS was the created and is used on many smart televisions.

  5. Hmm. These boards must also contain the HDCP decryption key and hardware, no?
    Sounds too trivial to turn this into a stream decryption engine. I’m guessing the manufacturers have thought of this back door and have locked it down somehow.

    1. Or a transplant. Has anybody tried to make an open source operating system for an OLED TV? These are amazing devices with horrible operating systems that could do so much more than they’re doing.

    2. Back in the day, television license fees were so detested that people took efforts to have a repair service remove the tuner out of a TV and write them a certificate that says this television can’t be used to receive broadcasts. They would only use it as a video monitor or playing games – though of course a VCR could tune into a broadcast channel and then play it back through the TV just as well. Then the law was switched to mean any device capable of receiving a TV broadcast, which meant that you had to have a TV license for your phone and your computer, at which point they just said sod it and forced everyone to pay a TV license through their income tax.

      1. I second that. Gratefully, pure video monitors without tuner also existed in the past. Like the famous Commodore 1702 monitor. Or all the other non-name home computer monitors, the green and amber monitors with an RCA input..

      2. As a colonial heathen (American) I still have a hard time wrapping my head around a tax to own a passive receiver, and enforcing that tax with detector vans that may or may not have actually worked.

        I say this knowing full well that no matter where I live in the U.S. I am going to pay a myriad of small taxes on silly things that I’ll likely never use let alone encounter. The fun part is evading them in such a way government flunkies are left standing around saying “He’s doing SOMETHING illegal, I just can’t prove it!”

        1. Here in Germany we had a tax for TVs and radios (!). The GEZ was charging a tax for owners of TVs or broadcast radios.

          Because, as their logic goes, if you owned a device capable of receiving the federal TV/radio programs you also had to pay in order to support those said networks.

          And if you didn’t own a TV, but a radio instead, you had to pay a smaller tax.

          Those radio-only tax payers were constantly treaded as liars by the GEZ, however. The GEZ constantly annoyed those radio fans, because it couldn’t believe that people had a radio, but not a TV.

          They acted as if they thought the radio-fans were merely ordinary TV owners that tried to out-smart the GEZ in order to play less. Paranoia at its best.

          I was a radio-only people myself in my young adult years and constantly got letters by the GEZ in which I was asked if I’m “still” a radio-only person.

          And that’s just the tip of the ice berg. It’s no wonder why people associated the GEZ with the maf*a.
          Their personell had really questionable methods of checking households for a TV.

          There are numerous stories about GEZ people entering houses without permission. They intimidated people who didn’t know their rights. Old ladies, kids etc. They acted as if they had the right to do so.

          Sometimes, that “illegal” TV they had found belonged to other family members who rightfully paid the taxes etc.

          Nowadays, the GEZ is gone. But the horror does not end. There’s a TV tax per household now. So every household must pay the tax. Pure radio owners nolonger exist. Problem is however, to find out who’s the householder. The person with the income, the house owner, the one with rental contract?

        2. in my city, normal people use a digital RFID style of card to pay to get onto a public bus.

          but if we pay cash on the bus, we avoid paying a provincial(state) gas/diesel tax by paying more…

          if everyone suddenly dropped using the cost-saving card at the same the gov would have to raise prices at the pump for people that drive… hmm i feel like they would not notice a small increase… happens everty week :P

  6. I have a couple of sky boxes that I have disassembled. They both have a broadcom chip in it. I have wondered is it possible to use them for anything else, since the chip used in the pi isn’t too different really. The Sky boxes contain two boards connected by really long header pins, but the lower board contains all the power electronics and maybe a few interfaces but the upper board contains the broadcom chip, the ram, flash and satellite dish signal input with a few more interfaces like hdmi.

    It isn’t easy to find much information on the chip with it being broadcom but if I could flash as OS onto it, that may be interesting.

  7. My tv sets, my dvd recorder, my GPS, they all run Linux. I know people have added utilities to the GPS. The tv set, which isn’t smart, had something about GPL in the manual, but only when I did an upgrade did I see it wss

  8. I would also like to see this kind of work grow, perhaps into an ecosystem like what came out of cyanogenmod for phones. Taking a spyware appliance (eg Smart TV) and making it into something that only does what you want, would be splendid IMHO.

  9. I have been poking at a Samsung 43″ UHD display, to the extent that I have the serial ports enabled, a copy of the eMMC (hence filesystems) from a different TV, and a spare controller board that I will eventually try to tamper with to get code execution on. The Samsung Tizen devices are fairly well locked down, it seems, to the extent that they are using Linux Security Modules to verify code execution of specific files, etc.
    But something will pop out, I’m sure of it! Let me know if anyone wants to collaborate!

  10. Interesting and worrisome that this SoC company is owned by various Russians and Russian shell companies. I wonder how secure our TV’s are and if there are backdoors in them.

  11. Does this mean we might finally be able to get rid of the stupid overscanning of digital inputs that makes modern TV’s so annoying to use with PC’s but can’t always be turned off because *reasons*? Seriously, why is this still a thing? If the “ancient” 10+ year old, 24 inch TV I have in my dorm (2nd display for laptop) can just display the image it’s given without a hassle, why can’t a brand new 4k panel just give me the same option?

    On that note, why the heck is overscan even still a thing? I get why it existed for analog television and its derivatives (composite video etc), but its reasons for existing are solved problems for modern inputs – VGA knew how to reliably detect and align the start of analog picture data from one line to the next a good 35 years ago! HDMI is fully digital, and it tells the display EXACTLY where the edges of the picture are, so what analog “messiness” are we still trying to cover up?
    As for the edge case of adapting older signals to modern inputs – is it really that expensive to give us just one more menu option???

    1. AJ: find a TV with Chroma 4:4:4 and that works as a monitor. I use a 43 inch 4K TCL as my monitor. It’s like having four 20-inch monitors.
      I don’t game, so I can’t comment on that performance. However, I can do wordprocessing in iMax. :)

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