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Micro camera data wireless transmission

Abhishek Madhyastha
Prodigy 105 points

Other Parts Discussed in Thread: TVP5146M2, CC2500, CC2400

Hi, I'm trying to transmit data(video) from the mini CCTV camera given in this link-
http://www.ebay.com/itm/new-170-degrees-HD-mini-cctv-camera-security-micro-camera-600TVL-SPY-CAMERA-A-/161175497366 over RF to a LCD display circuit.

I don't need the processor in my circuit to do any sort of manipulation with the video. The camera outputs in PAL/NTSC format & this output should be merely transmitted to my display circuit over RF. The ez430-rf2500 would be an easy solution for this as I'm familiar with MSP430 series & this model has a transceiver & an ADC built into it. Also, low power is a critical requirement in my design which can be achieved with the ez430. Using 2 of these devices, I can transmit the camera output from 1 ez430 to another and then to my display.

However, I happened to find out that the MSP430 series lacks the RAM capacity to process videos. Since, I don't need to do any "processing" with the video output, would it be possible to still use the ez430? Resolution, definition, quality,etc are not of much importance to me. The video must be "viewable" on the display, that's it.
If not, how should I go about with this problem? Which processor/launchpad/etc should I use for this? Is there something similar to the ez430 which is meant for such purposes?

Please note that the device needs to be very power efficient and small in size like the ez430.

  • 0
    Guru 46710 points

    Video is high bandwidth application. Before you even consider to choose hardware for video capture and transmission, first thing you do - calculate channel bitrate. Also you shall think how to get analog video into digital format. Questions you shall answer to us and yourself - what's video resolution, color depth and frame rate?

    Does 200KSps ADC is enough to digitize your video? Does throughput of radio is enough to transmit it? How do you receive it and display on LCD without buffering? Does LCD have built-in framebuffer?

    Abhishek Madhyastha said:
    Since, I don't need to do any "processing" with the video output, would it be possible to still use the ez430?

    Most probably not. Try to do your homework and you will see why.

  • 0 in reply to Ilmars
    Prodigy 105 points

    Thanks for the reply.

    IImars said:
     first thing you do - calculate channel bitrate

    As far as channel rate is concerned, 200-300kbit/s is sufficient. 
    IImars said:
    Also you shall think how to get analog video into digital format.

    The thing is, the camera circuit must merely capture the video & transmit it off to the receiver display circuit. Its like, the transmitting circuit merely "dumps" the camera output to the receiver. The conversion from analog(PAL/NTSC) to digital must take place preferably at the receiver end because the camera circuit must consume as low power as possible(that's the main part of the project). So, all the processing,etc must take place only at the receiver side. In fact, I chose the ez430 only because I'm already using it for other purposes on the same camera circuit & I can avoid the transmitter circuit design which is inbuilt in it. The conversion from PAL/NTSC to digital is to be done using a TVP51xx family decoder.
    Ilmars said:
    what's video resolution, color depth and frame rate?

    The LCD has a resolution of 240x320(the camera resolution is higher). The camera offers a frame rate of 60f/s(30f/s would be sufficient). 
    IImars said:
    Does throughput of radio is enough to transmit it? How do you receive it and display on LCD without buffering?

    The sole reason I preferred the ez430 is because it has an internal tranceiver, so that I don't have to get into transmitter design.
    Ilmars said:
    Does LCD have built-in framebuffer?

    The LCD has an inbuilt video RAM buffer.
    Ilmars said:
    Most probably not. Try to do your homework and you will see why.

    I know that the MSP430 series cannot handle such massive data stream but as I've already mentioned, I don't want to get into transmitter design because that's not the core of the project & only the ez430 has an internal tranceiver.

    Please note that, its the power design for the camera end circuit that's of core importance & not the camera circuit itself! The latter serves as a mere application or demonstration for the innovative power design(MOST IMPORTANT PART) that I'm using. Hence, output quality, resolution, bitrate,etc are not of much importance to my project. I'm an EE student & don't know much about image processing. If it consumes low power & displays with even "ok" quality, I'm fine with it.

  • 0 in reply to Abhishek Madhyastha
    Guru 46710 points

    Abhishek Madhyastha said:
    the innovative power design(MOST IMPORTANT PART)

    Are you sure your camera is as power-effective as msp430? :)

    You missed to address most important parts of your homework. To do 240x320 pixels, 30fps at 8 bits/pixel, you need 240*320*30*8 = 18432000 bits per second. 18 Megabits! What's max transmission bitrate of selected radio?

    240x320x30 = 2.3 Mega Pixels Per Second. Remember that msp430 have ADC that can do 200000 samples per second. 10 times slower. Also you need to __process__ video signal because you need to find frame/line sync. This means you need plenty of computing power too.

    Abhishek Madhyastha said:
    If it consumes low power & displays with even "ok" quality

    But it can't.

  • 0 in reply to Ilmars
    Prodigy 105 points

    IImars said:
     Are you sure your camera is as power-effective as msp430? :)



    The camera is a low power one but no match to the msp430! :-P

    IImars said:
     What's max transmission bitrate of selected radio?


    I reiterate, I chose the ez430 only because it has a transceiver as a result of which I can avoid transmitter design. So, I haven't gone into transmitter circuit design.

    IImars said:
     Remember that msp430 have ADC that can do 200000 samples per second. 10 times slower. Also you need to __process__ video signal because you need to find frame/line sync. This means you need plenty of computing power too.  


    I hadn't noticed that the msp430's ADC has a 200000 Sps cap(should have read the data sheet in detail :-) ).
    Since, msp430 series is out of question, I believe the TIVA ARM series would be the best option?

    Also, how can I about with the transmitter design without getting into much details?(I'm from an EE background, so, transmitter design is quite alien to me). 

    Would an ARM processor with RS232 transceiver & TVP5146M2 decoder be a solution? If so, could you point me to some sample designs?

  • 0 in reply to Abhishek Madhyastha
    Guru 227245 points

    Abhishek Madhyastha said:
    I hadn't noticed that the msp430's ADC has a 200000 Sps

    It' seven higher - in theory, you can get it as high as 460ksps (requiring a low-impedance source). But is of course no special high-frequency video signal ADC. But even if it were, with 2.3msps you have exactly 10 CPU cycles per byte to forward it form ADC to the LCD. Including sync recognition etc. Even a plain fire&forget SPI output with DMA and no CPU interaction would barely cover this data rate. No MSP works with more than 25MHz system clock.

  • 0 in reply to Abhishek Madhyastha
    Guru 46710 points

    Abhishek Madhyastha said:
     What's max transmission bitrate of selected radio?



    I reiterate, I chose the ez430 only because it has a transceiver as a result of which I can avoid transmitter design. So, I haven't gone into transmitter circuit design.[/quote]

    First you shall read specification of chips you consider to use, only then think about circuit design. Apparently you did not read specs.

    Abhishek Madhyastha said:
    Also, how can I about with the transmitter design without getting into much details?(I'm from an EE background, so, transmitter design is quite alien to me). 

    No problem. Even companies sometimes uses 3rd party radio modules in their products for exactly same reason.

    To conclude: web page of ez430-rf2500 have link to CC2500 chip datasheet which states that particular radio have max 500 kBaud (0.5 Mbits) transmission rate. Far from enough for real time 320x240 @30fps video. Surprise, huh?

  • 0 in reply to Ilmars
    Prodigy 105 points

    IImars said:
     To conclude: web page of ez430-rf2500 have link to CC2500 chip datasheet which states that particular radio have max 500 kBaud (0.5 Mbits) transmission rate. Far from enough for real time 320x240 @30fps video. Surprise, huh?



    Well, wouldn't call it a surprise, but yes, an eye opener. :-)

    I've decided to go for the C3088 camera instead of the previous one because it gives direct digital output.
    I also happened to come across a reference design for a wireless camera. It uses a resolution of 248*192 & the AT86RF230 trasciever. Its quite similar to the CC2500. The camera uses progressive capture method & in this design horizontal capture has been uses out of the 3 modes available. The link to both these can be found here.
    CAMERA- http://www.sunrom.com/100
    AT86RF230- http://www.atmel.in/images/doc5131.pdf

    The only difference now is that, the video is available directly in digital form & hence no more need for the ADC. The camera is made to run at a frequency of 120kHz while the AVR mcu ATmega644P runs at 8MHz! This 8 bit mcu is hardly as powerful as an MSP430!
    ATmega644P-http://www.atmel.in/Images/Atmel-8011-8-bit-AVR-Microcontroller-ATmega164P-324P-644P_summary.pdf

    How is it that the design manages to use this transciever which is more or less the same as CC2500 & that too with an 8 bit AVR mcu? Is it because of the camera? Am I missing something here?

  • 0 in reply to Abhishek Madhyastha
    Guru 46710 points

    Abhishek Madhyastha said:
    Am I missing something here?

    Yes. Frame rate.

    Do you know what calculator is? - Useful device. Most computers have built-in calculator too :)

    Even at 176 × 144, 8 bits/pixel you need 25344 bytes per single video frame. Your "new" radio maximum transmission speed is 250kbits/s which means you will have 250000/(25344*8) = 1.2 FPS of so called "video". Does not meet your specs. I can press shutter button on my photo camera faster :D

    [edit] Sorry to say - I don't think this project is for you. Better rethink your plans and build wireless temperature sensor/display

  • 0 in reply to Ilmars
    Prodigy 105 points

    IImars said:
     

    Yes. Frame rate.

    Do you know what calculator is? - Useful device. Most computers have built-in calculator too :)

    Even at 176 × 144, 8 bits/pixel you need 25344 bytes per single video frame. Your "new" radio maximum transmission speed is 250kbits/s which means you will have 250000/(25344*8) = 1.2 FPS of so called "video". Does not meet your specs. I can press shutter button on my photo camera faster :D



    That's exactly what I mean. Yes, I did use a calculator and that's exactly what I found out. Does this mean that that reference design is wrong or even worse, fake? 1.2 FPS is more or less the same as a still camera!
    I'm considering reducing the resolution to 176x144(its not that important to me) & the FPS to 15. Even then I need roughly 3.1Mbits/s. The CC2400 offers a max speed of 1Mbits/s. I just cant find a transceiver with such speed! But, toy helicopters do use wireless data transmission for transmitting camera data. So, its definitely possible to do so!
    Also, I'll be using a TIVA series ARM mcu instead of a MSP430.

    IImars said:
    [edit] Sorry to say - I don't think this project is for you. Better rethink your plans and build wireless temperature sensor/display

    Irrespective of whether you wish to help me or not, I will do this project. I've made up my mind. The camera system is the only thing remaining in the project & I must do it. I would be very thankful if you would comply & help me.
    All I need is help in finding the right transceiver or modifying an existing one for this purpose. Please do help me out.

  • 0 in reply to Abhishek Madhyastha
    Guru 46710 points

    Abhishek Madhyastha said:
    Does this mean that that reference design is wrong or even worse, fake?

    Which reference design? You mean sorre face recognition demo? Do they mention any performance figures?

    Abhishek Madhyastha said:
    I just cant find a transceiver with such speed!

    WiFi is not that hard to find.

    Abhishek Madhyastha said:
    But, toy helicopters do use wireless data transmission for transmitting camera data.

    Those use analog video transmitters/receivers. Don't compare apples to oranges, they ARE different.

    Abhishek Madhyastha said:
    Please do help me out.

    Don't waste your time trying to do this project using msp430 which is designated for completely another field of applications. Much more realistic hardware would be: h.264 camera or USB video capture adapter, two ARM microcontroller (boards) like Raspberry PI, WiFi USB dongles. And yes: Linux.

  • 0 in reply to Ilmars
    Prodigy 105 points

    IImars said:
    Those use analog video transmitters/receivers. Don't compare apples to oranges, they ARE different.



    Could you explain more about this? Actually, my project would be used with the camera side system being aviated for small heights and distance. So, its more related to the toy helicopter rather than security/surveillance camera systems. Light weight, low power, small size,etc are a necessity because of this.

    IImars said:
    Much more realistic hardware would be: h.264 camera or USB video capture adapter, two ARM microcontroller (boards) like Raspberry PI, WiFi USB dongles. And yes: Linux.


    Usage of the ARM mcu is fixed. WiFi USB dongles as you suggested would certainly solve this problem. But won't the h.264 camera increase the size?(which is not preferable for aviation)

    Please tell me more about or provide me some resources regarding the analog video transmitter/receiver that you mentioned about.

  • 0 in reply to Abhishek Madhyastha
    Guru 46710 points

    Abhishek Madhyastha said:
    Actually, my project would be used with the camera side system being aviated for small heights and distance. So, its more related to the toy helicopter rather than security/surveillance camera

    Why didn't you tell this from the very beginning? - You tried to invent thermonuclear bicycle. Better just buy ordinary one and ride. Here's your ticket: http://bit.ly/Mn7JFu

    Thing is that if you need just remote video display for short distances that don't consume much power, space and weight then you can't beat oldkool analog video transmission systems. I do not want to go into details because it's out of scope here.

  • 0 in reply to Abhishek Madhyastha
    Guru 227245 points

    Abhishek Madhyastha said:
    Those use analog video transmitters/receivers. Don't compare apples to oranges, they ARE different.



    Could you explain more about this?[/quote]Analog video transmission uses the modulation of the HF signal to represent the actual analog video signal. Digital image transmission requires each sample point to be represented by multiple bits and each bit requires a full HF modulation cycle. So the required HF bandwidth is (assuming rgb 8 bit = 24bit/pixel) at least a factor of 24 higher than the required analog bandwidth. Usually even (much) more.

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