Visible Light Communication

Discussion in 'The Projects Forum' started by nhmdp, Jun 13, 2014.

  1. nhmdp

    Thread Starter New Member

    Apr 28, 2013
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    We are doing a project on Visible Light Communication(VLC) using MSP430. Our project is about sending data from one laptop to another using VLC.

    At the transmitter end, msp430 is connected to TLC5916 which is a LED driver. This driver has 8 output LEDs. The serial data from MSP430 is converted to parallel in the LED driver and output is through LEDs. This data in LED is received by the photodiode OPT101 at the receiver.

    The doubt that we have got is, can the photodiode detect the data as the data is coming from the 8 LEDs or can it detect data from only one LED at a time? Is it possible to send the data from the driver through only one LED?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    The photodetector can only detect the output of one LED. It is a mistake to convert the serial data to parallel.

    VLC communication is no different from other forms of communication such as IR, RF, Bluetooth, USB, ethernet, etc. where data is transmitted serially.

    There are already three common ways of formatting serial communications, NRZI (e.g. UART), PWM, and Manchester phase encoding.
     
  3. nhmdp

    Thread Starter New Member

    Apr 28, 2013
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    We are confused about the working of TLC5916 - LED driver. We have seen some experiments where this same driver was used and the photodiode detected the signals. So have we got it wrong about the driver that it gets converted to parallel?

    Or should we try some other LED drivers?
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    You do not need a TLC5916 or any other LED driver. A simple 220Ω resistor in series with almost any LED will be sufficient to limit the LED current.
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Unless the 5916 is a project requirement, it seems overly complicated for the task you have described.

    Two laptops do not communicate with each other by default. Both must be running a software program to accomplish this, a form of peer-to-peer networking. So I think the first step is to do this with a wired connection, such as a crossover serial cable between the two machines serial ports. Once you have communications established, the cable can be replaced with your electronics project.

    Despite having 9 or 25 pin connectors, a serial port has only one transmit wire and one receive wire. For that you will need only one transmitting LED (and no special driver) and one OPT101 for each direction. OPT101 bandwidth is only 14 KHz, so your data link will be very slow (start at 2400 baud and increase if working).

    ak
     
  6. wayneh

    Expert

    Sep 9, 2010
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    A laptop with a serial port? Good luck with that. :rolleyes:
     
  7. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Yeah, but with a 14 KHz bandwidth limit, what else is there?

    ak
     
  8. Ninja92

    New Member

    Aug 28, 2014
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    will you tell me detailed information about ur project sir
     
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