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Is FDP-Link only for video?

adsfsadfadsfda
Prodigy 80 points
Other Parts Discussed in Thread: DS90LV012A, DS90LV011A, DS90LT012A, DS90LV028A, DS90LV027A, THVD1450, SN65LVDT41, DS90UA101-Q1

I'm looking at sending around 50 Mbps of data over a cable about 3 ft in length. None of the MCU have UART that can go that speed, so I am starting to look at some SERDES chips that can transmit over something like LVDS.

It looks like the only chips TI offers are FDP-Link. I'm not familiar with FDP-Link yet, but it appears that this is meant for video. Is there any reason this couldn't just be used for arbitrary data? Is there any better protocol? Minimizing the number of wires is important, and it looks like you can also do power over a data line, which would be great. These serializers and deserializers also seem very power-hungry.

  • 0
    Guru 257000 points

    FPD-Link serializers/deserializers can be used to transmit arbitrary signals, as long as they are similar enough to video signals, i.e., many channels of digital CMOS/LVDS signals with a common clock.

    How many channels do you want to serialize?

  • 0 in reply to Clemens Ladisch
    Prodigy 80 points

    Just one channel. I was going to use UART, but those seem to top out at 10-20 MHz, so I need something faster.

  • 0 in reply to adsfsadfadsfda
    Guru 257000 points

    A serializer combines many slow channels into one fast channel.

    To transmit a single channel, what you want is just a transmitter and a receiver, e.g., DS90LV011A and DS90LV012A/DS90LT012A.

    What protocol are you going to use with your microcontroller? A simple asynchronous protocol (like UART) will not work at 50 Mbps; a simple synchronous protocol like SPI requires at least an additional clock line. (There are dual-channel devices like the DS90LV027A/DS90LV028A.)

    For very noisy environments, consider RS-485 transceivers like the THVD1450, but those are more power hungry.

  • 0 in reply to Clemens Ladisch
    Prodigy 80 points

    As you say, SerDes style links are attractive because they combine clock and data into two wires. My original plan was to use UART through an LVDS transceiver, but also like you said, UART is not fast enough and SPI would require two extra wires. I'm not even sure if a synchronous protocol like SPI at that speed would work through 3 ft wires (skew, etc.)

  • 0 in reply to adsfsadfadsfda
    Guru 257000 points

    LVDS is commonly used for SPI. (There are devices like the SN65LVDT41/14 to handle the full set of CS/CLK/MISO/MOSI signals.) Having several LVDS channels should not be too much a problem.

    An FPD-Link serializer needs a continuous clock that it can synchronize to. This is not how SPI works. (FPD-Link is designed for video with lots of parallel signals; the only exception are the DS90UA101-Q1/102 for audio, but with the same clocking problem.)

    Another protocol that can handle 50 Mbps would be Ethernet. But it's probably overkill for a 3 ft cable.

  • 0 in reply to Clemens Ladisch
    TI__Guru 58705 points

    Hi Adam, 

    FPD-Link SerDes might be a bit overkill here, but isn't technically limited to purely RGB data. Provided the proper clocking and data, it could theoretically be sent across the link and post processed into other information. 

    Regards, 

    Logan