HT-12E encoder question

Discussion in 'Electronic Design' started by sommes, Mar 28, 2006.

  1. sommes

    sommes Guest

    There is four input in HT-12E, can I only use one input and ignore other
    three inputs to input a 10bits serial digital data from ADC?

    Thank you very much.
     
    sommes, Mar 28, 2006
    #1
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  2. sommes

    Donald Guest

    sommes wrote:
    > There is four input in HT-12E, can I only use one input and ignore other
    > three inputs to input a 10bits serial digital data from ADC?
    >
    > Thank you very much.
    >
    >

    I think you need to read the data sheet.

    Just in case here it is:
    http://www.commlinx.com.au/HT12E.pdf

    This device take 12 parallel bits and converts them to a serial data stream.

    Thats all.

    You still need some sort of transmitter.

    From the first page "General Description":

    " The programmed addresses/data are transmitted together with the header
    bits via an RF or an infrared transmission medium upon receipt of a
    trigger signal."

    SO you need to provide the "transmission medium".
    You also need to provide a "trigger signal" (TE)

    When the TE signal is low, the HT-12E will transmit the 12 bits over and
    over again till TE goes high.

    I do not think this device will you what you expect.

    By the way, what is it you are trying to do ???

    donald
     
    Donald, Mar 28, 2006
    #2
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  3. sommes wrote:
    > There is four input in HT-12E, can I only use one input and ignore other
    > three inputs to input a 10bits serial digital data from ADC?


    Yes, you could do this, but how are you going to reassemble the bits on
    the other end?
    What happens if a packet is duplicated or dropped?

    This chip is really designed as a four button remote control, so you
    are using it in a way it was not intended, which is often a problem.

    You might get it to work with a parallel ADC, sending all 10 bits at a
    time. This way, each packet would contain the entire 10 bits. But you
    would only have 2 bits left for addressing.

    Alan Nishioka
     
    Alan Nishioka, Mar 28, 2006
    #3
  4. sommes

    sommes Guest

    Thank you Donald, Alan

    Thank you for your reply. I am going to list what I try to do.

    1) Input 0 to 5V to Atmel AVR AT90S8535

    2) 10bit ADC conversion by 8535

    3) Encode with HT-12E and transmit by TLP-343

    4) Recieve by RLP-343 and Decode with HT-12D

    5) Display infomation by 7 Segment display.

    I would lik to ask.

    Q1) Can Atmel 8535 do the 10bit ADC and output data from RS-232(serial
    output)?

    Q2) Do I need encode HT-12E if serial data is achieved?

    Q3) Can I just input the serial data from ADC to TLP-343 transmitter?
     
    sommes, Mar 29, 2006
    #4
  5. sommes

    sommes Guest

    transmitter should be TLP-434
    reciever should be RLP-434
     
    sommes, Mar 29, 2006
    #5
  6. sommes wrote:
    > Q1) Can Atmel 8535 do the 10bit ADC and output data from RS-232(serial
    > output)?


    Probably


    > Q2) Do I need encode HT-12E if serial data is achieved?


    Probably not. It does seem silly to convert to parallel then back to
    serial.


    > Q3) Can I just input the serial data from ADC to TLP-343 transmitter?


    Probably.

    http://www.serasidis.gr/circuits/RF_remote_control/RF_remote_control.htm
    used an avr directly connected to tlp434a for his project.

    www.laipac.com would not let me download datasheets.

    Alan Nishioka
     
    Alan Nishioka, Mar 29, 2006
    #6
  7. sommes

    Donald Guest

    sommes wrote:
    > Thank you Donald, Alan
    >
    > Thank you for your reply. I am going to list what I try to do.
    >
    > 1) Input 0 to 5V to Atmel AVR AT90S8535
    >

    Ok

    > 2) 10bit ADC conversion by 8535
    >

    OK

    > 3) Encode with HT-12E and transmit by TLP-343
    >

    Why ?

    Connect the TLP-343 to a port bit and create a 10 bit serial data stream.

    > 4) Recieve by RLP-343 and Decode with HT-12D
    >

    Again why the HT-12D ?

    Output of RLP-3433 into port bit of another 8535.

    > 5) Display infomation by 7 Segment display.
    >

    8535 can do this as well.

    > I would lik to ask.
    >
    > Q1) Can Atmel 8535 do the 10bit ADC and output data from RS-232(serial
    > output)?


    Yes

    >
    > Q2) Do I need encode HT-12E if serial data is achieved?
    >

    NO


    > Q3) Can I just input the serial data from ADC to TLP-343 transmitter?
    >
    >

    Yes

    Alan, nice link.

    To get ideas for transmit/receive encoded data, google for "manchaster
    coding".

    All this sounds like it will be a lot of work. ( well, for the first
    time it will be).

    There are a lot of projects out on the net to help you along.

    Good Luck

    donald
     
    Donald, Mar 29, 2006
    #7
  8. sommes

    sommes Guest

    Thank you Donald and Alan again.

    Can I ask you one more question?

    I am using HT-12E, becuase my industry partner told me the encoder is doing
    some kind of encoding which enable to get rid of noise and the reciever
    could recieve the encoded data correctly, therefore my partner suggest me to
    use HT-12E and using the 4 bits input from the chip to send 10bits with 3
    cycles(4 bit for one cycle).

    Please correct me if it was wrong.
     
    sommes, Mar 29, 2006
    #8
  9. sommes

    Donald Guest

    sommes wrote:
    > Thank you Donald and Alan again.
    >
    > Can I ask you one more question?
    >
    > I am using HT-12E, becuase my industry partner told me the encoder is doing
    > some kind of encoding which enable to get rid of noise and the reciever
    > could recieve the encoded data correctly, therefore my partner suggest me to
    > use HT-12E and using the 4 bits input from the chip to send 10bits with 3
    > cycles(4 bit for one cycle).
    >
    > Please correct me if it was wrong.
    >
    >

    I am sorry, but this does not make any sense.

    But, if thats what the client wants......

    donald

    PS: noise is what the "manchaster encoding" will help with.
     
    Donald, Mar 29, 2006
    #9
  10. sommes wrote:
    > I am using HT-12E, becuase my industry partner told me the encoder is doing
    > some kind of encoding which enable to get rid of noise and the reciever
    > could recieve the encoded data correctly


    The HT-12E encodes a 1 as a short pulse and a 0 as a long pulse. This
    allows clock recovery at the receiving end. But there is nothing
    special about this code that gives it better noise immunity. That
    would depend on what is built into the decoder.

    And any kind of coding/decoding could be done in the AVR.
    But you would also have to do any decoding for noise immuity on your
    own too.


    > therefore my partner suggest me to
    > use HT-12E and using the 4 bits input from the chip to send 10bits with 3
    > cycles(4 bit for one cycle).


    I still don't see how you will be able to tell where the beginning of
    an ADC data word is using this method. If you want to use the HT-12E,
    I still suggest sending 10 bits in parallel in a single packet.

    Alan Nishioka
     
    Alan Nishioka, Mar 29, 2006
    #10
  11. sommes

    Donald Guest

    Alan Nishioka wrote:

    > sommes wrote:
    >
    >>I am using HT-12E, becuase my industry partner told me the encoder is doing
    >>some kind of encoding which enable to get rid of noise and the reciever
    >>could recieve the encoded data correctly

    >
    >
    > The HT-12E encodes a 1 as a short pulse and a 0 as a long pulse. This
    > allows clock recovery at the receiving end. But there is nothing
    > special about this code that gives it better noise immunity. That
    > would depend on what is built into the decoder.
    >
    > And any kind of coding/decoding could be done in the AVR.
    > But you would also have to do any decoding for noise immuity on your
    > own too.
    >
    >
    >
    >>therefore my partner suggest me to
    >>use HT-12E and using the 4 bits input from the chip to send 10bits with 3
    >>cycles(4 bit for one cycle).

    >
    >
    > I still don't see how you will be able to tell where the beginning of
    > an ADC data word is using this method. If you want to use the HT-12E,
    > I still suggest sending 10 bits in parallel in a single packet.
    >
    > Alan Nishioka
    >


    Hello Alan,

    I think we agree that the HT-12E is not needed in this application.

    But, I am confused about "sending 10 bits in parallel in a single packet".

    Sending 10 bits in a Manchester Encoding scheme would give a
    self-clocking data stream.

    http://en.wikipedia.org/wiki/Manchester_encoding

    donald

    PS: Now its up to the OP to decide how much work he wants to do.
    I think the amount of work to get the HT-12E working is much more
    difficult.
    So I hope the OP is charging by the hour. ;-)
     
    Donald, Mar 29, 2006
    #11
  12. sommes wrote:
    > I am using HT-12E, becuase my industry partner told me the encoder is doing
    > some kind of encoding which enable to get rid of noise and the reciever
    > could recieve the encoded data correctly, therefore my partner suggest me to
    > use HT-12E and using the 4 bits input from the chip to send 10bits with 3
    > cycles(4 bit for one cycle).


    I finally read the HT12D datasheet to see what it does for noise
    immunity.
    The HT12E sends the same address/data four times in a row.
    The HT12D compares the four transmissions to see if they are all the
    same.

    Also, my suggestion of sending 10bits at a time won't work because it
    compares the address bits.

    I think it would be easier to use the AVR to do any encoding / decoding
    / noise immunity.

    Alan Nishioka
     
    Alan Nishioka, Mar 29, 2006
    #12
  13. Donald wrote:
    > I think we agree that the HT-12E is not needed in this application.


    Yes.


    > But, I am confused about "sending 10 bits in parallel in a single packet".


    The receiver needs to know where the MSB of the ADC data is. I was
    trying to use the address bits on the HT-12E to send more data (the
    whole 10bit word in one burst). I did not realize that the decoder
    treated these address bits specially, so this won't work.


    > > Sending 10 bits in a Manchester Encoding scheme would give a

    > self-clocking data stream.


    Yes, that would be good to get the bits across, but that doesn't tell
    you where the MSB is. I believe the project I referenced earlier just
    used RS232 signaling, which should work and give you the MSB too.


    > PS: Now its up to the OP to decide how much work he wants to do.
    > I think the amount of work to get the HT-12E working is much more
    > difficult.


    I agree.


    > So I hope the OP is charging by the hour. ;-)


    Perhaps we should be charging him! :)

    Alan Nishioka
     
    Alan Nishioka, Mar 29, 2006
    #13
  14. sommes

    Donald Guest

    Alan Nishioka wrote:
    >
    >
    > Perhaps we should be charging him! :)
    >
    > Alan Nishioka
    >


    :):):):)
     
    Donald, Mar 29, 2006
    #14
  15. sommes

    sommes Guest

    Thank you Alan and Donald again, I really learnt a lot from you guys...By
    the way.

    I will talk to my partner but it is little bit hard to change his mind. It
    is becuase he think

    1) Using HT-12E and HT-12D could get rid of noise, and data can send
    correctly

    2) I can output 10bits ADC serials data to1 of the 4 input from HT-12E to
    send the data easily, however it would be very slow to do in this way,
    therefore, my partner suggest me to use all 4 input from HT-12E to send at
    same time.

    What is the best solution to radio transmission 10bit ADC data from Atmel
    AT90S8535?

    Sorry for my bad knowledge of RF
     
    sommes, Mar 30, 2006
    #15
  16. sommes

    Tim Wescott Guest

    sommes wrote:

    > Thank you Alan and Donald again, I really learnt a lot from you guys...By
    > the way.
    >
    > I will talk to my partner but it is little bit hard to change his mind. It
    > is becuase he think
    >
    > 1) Using HT-12E and HT-12D could get rid of noise, and data can send
    > correctly
    >
    > 2) I can output 10bits ADC serials data to1 of the 4 input from HT-12E to
    > send the data easily, however it would be very slow to do in this way,
    > therefore, my partner suggest me to use all 4 input from HT-12E to send at
    > same time.
    >
    > What is the best solution to radio transmission 10bit ADC data from Atmel
    > AT90S8535?
    >
    > Sorry for my bad knowledge of RF
    >
    >

    Looking at the data sheet from Laipac for the transmitter and receiver,
    you _should_ be able to hook up asynchronous serial output from the
    micro to input pin of the transmitter, and see more or less the same
    signal on the receiver pin of the matching receiver. You'll have to
    take the 10 bit number and split it up -- the easiest thing to do might
    be to just send two bytes, wait a while, then send the next reading, etc.

    Better would be to send it with a checksum of some sort because with
    radio you're practically guaranteed bad data at some point. If I just
    wanted to send one channel of analog data I'd probably have a five-byte
    packet: an unambiguous header (0x55?), two data bytes, then a CRC16
    checksum. If you don't want to do CRC16 and don't mind a greater chance
    of error you could use CRC8, or even a sum-of-bytes, but a CRC would be
    significantly better.

    The next time you ask one of these questions you may get better response
    if you:

    * say what you're doing beyond just sending data
    * include pertinent details, like data rates and frequencies
    * tell us what you _do_ know
    * don't assume that we know what company's products you're using
    * don't assume we know everything about that company's products
    * don't assume that we want to go read their website

    Something like "I want to send data at 4800 baud on a 434MHz data link.
    I'm going to use an Laipac HT-whatever plus a TRX-whatever else, and I
    need to know how to make it all work."

    --

    Tim Wescott
    Wescott Design Services
    http://www.wescottdesign.com

    Posting from Google? See http://cfaj.freeshell.org/google/
     
    Tim Wescott, Mar 30, 2006
    #16
  17. sommes

    Ken Taylor Guest

    Tim Wescott wrote:
    > sommes wrote:
    >
    >> Thank you Alan and Donald again, I really learnt a lot from you guys...By
    >> the way.
    >>
    >> I will talk to my partner but it is little bit hard to change his
    >> mind. It
    >> is becuase he think
    >>
    >> 1) Using HT-12E and HT-12D could get rid of noise, and data can send
    >> correctly
    >>
    >> 2) I can output 10bits ADC serials data to1 of the 4 input from HT-12E to
    >> send the data easily, however it would be very slow to do in this way,
    >> therefore, my partner suggest me to use all 4 input from HT-12E to
    >> send at
    >> same time.
    >>
    >> What is the best solution to radio transmission 10bit ADC data from Atmel
    >> AT90S8535?
    >>
    >> Sorry for my bad knowledge of RF
    >>
    >>

    > Looking at the data sheet from Laipac for the transmitter and receiver,
    > you _should_ be able to hook up asynchronous serial output from the
    > micro to input pin of the transmitter, and see more or less the same
    > signal on the receiver pin of the matching receiver. You'll have to
    > take the 10 bit number and split it up -- the easiest thing to do might
    > be to just send two bytes, wait a while, then send the next reading, etc.
    >
    > Better would be to send it with a checksum of some sort because with
    > radio you're practically guaranteed bad data at some point. If I just
    > wanted to send one channel of analog data I'd probably have a five-byte
    > packet: an unambiguous header (0x55?), two data bytes, then a CRC16
    > checksum. If you don't want to do CRC16 and don't mind a greater chance
    > of error you could use CRC8, or even a sum-of-bytes, but a CRC would be
    > significantly better.
    >
    > The next time you ask one of these questions you may get better response
    > if you:
    >
    > * say what you're doing beyond just sending data
    > * include pertinent details, like data rates and frequencies
    > * tell us what you _do_ know
    > * don't assume that we know what company's products you're using
    > * don't assume we know everything about that company's products
    > * don't assume that we want to go read their website
    >
    > Something like "I want to send data at 4800 baud on a 434MHz data link.
    > I'm going to use an Laipac HT-whatever plus a TRX-whatever else, and I
    > need to know how to make it all work."
    >

    If noise is seriously considered a problem would it be worth trading off
    some throughput speed by using all four of the inputs for one-bit data,
    with two bits inverted and two bits non-inverted. Check at the receiver
    to derive a confidence bit.

    Ken
     
    Ken Taylor, Mar 30, 2006
    #17
  18. sommes

    Donald Guest

    sommes wrote:
    > Thank you Alan and Donald again, I really learnt a lot from you guys...By
    > the way.
    >
    > I will talk to my partner but it is little bit hard to change his mind. It
    > is becuase he think


    Some how I do not think thats the real problem.


    >
    > 1) Using HT-12E and HT-12D could get rid of noise, and data can send
    > correctly
    >

    Is it that, he thinks a tiny piece of cheap hardware is better than 4
    weeks of software development ?

    After the software is developed, there are no HT chips at all.


    > 2) I can output 10bits ADC serials data to1 of the 4 input from HT-12E to
    > send the data easily, however it would be very slow to do in this way,
    > therefore, my partner suggest me to use all 4 input from HT-12E to send at
    > same time.
    >

    Silly, but doable. Just takes time.


    > What is the best solution to radio transmission 10bit ADC data from Atmel
    > AT90S8535?
    >


    Its been stated several times already.

    One bit out to Tx, one bit in from Rx.

    > Sorry for my bad knowledge of RF
    >
    >


    This is has not been an RF problem, its a software problem.

    How much software ( in other words, how much will it cost ) do you eant
    to develop ?

    Show your partner these posts. Tell him it will be cheaper with the
    software method.

    donnald


    Let us know what you end up doing.
     
    Donald, Mar 30, 2006
    #18
  19. sommes

    Steve Guest

    On Thu, 30 Mar 2006 11:03:49 +1000, "sommes" <> wrote:

    >What is the best solution to radio transmission 10bit ADC data from Atmel
    >AT90S8535?


    I have done this with a PIC, not an Atmel chip, on the PIC serial
    interface you have the option of sending a 9 bit byte instead of the
    usual 8. So you can use that extra bit as a way to code whether the
    byte you are sending is the high or low byte of your 2 byte data
    sample. It's not as good as sending in frames and doing proper
    checksums, but it's a simple way to send 10-16 bit data over a radio
    link, you can check at the receiver that you are getting pairs of
    bytes, generate an error if not, discard some data and then
    resynchronise. I have no idea if the Atmel chip can also do this in
    it's hardware, maybe not, though if you write your own serial output
    code to drive a pin on the Atmel then you could implement this method.

    Steve
     
    Steve, Mar 30, 2006
    #19
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