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Samsung IR transmission protocol & msp430

erdem simsek
Expert 2165 points
Other Parts Discussed in Thread: MSP430G2553

Hi everyone ,

I know that , this topic is not  completely  interested in here . But i wanna control samsung tv with msp430 (msp430g2553) . There are little data about how it occur. 

I found something :

elektrolab.wz.cz/.../samsung_protocol.pdf //file from Samsung

usgroup.eu/.../infrared-emitter // application

lirc.sourceforge.net/.../lircd.conf.samsung //command list

i  did my system according to these source . It does not work . I think , samsung does not use this for their smart tv. Because i check it with oscilloscope , 
then result :
 (channel 1)

4.1 ms high
1 ms low

1.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

0.3 ms high
0.9 ms low

1.3 ms high
0.9 ms low

ms = milisecond

as far as i know , samsung uses 39.2 kHz  , one start bit , one stop bit and 32 data bit

digital zero 0.56ms high - 0.56 ms low

digital one 0.56 ms high - 1.69 ms low

start bit 4.5 ms high - 4.5 ms low

why are there these difference  ? 

Thank you

  • 0
    Guru 46710 points

    What you recorded seems to me like original Samsung protocol - just inverted and with puse length skew to one side.  0.56+0.56ms = 1.12ms,  0.9+0.3ms = 1.2ms. 0.56+1.69=2.25, 1.3+0.9 = 2.2. Both are very close. Idea for such kind of pulse position RC protocols is not about matching exact baud frequency but about detection of short versus long pulse to discriminate between 0 and 1.

  • 0
    Guru 23000 points

    Maybe the example software and/or documentation on this page http://www.ti.com/tool/boost-ir can help you.

  • 0 in reply to Ilmars
    Expert 2165 points
    Thanks , i will try your idea . It is very logical
    Now , (digital zero ) 0.56ms high 0.56ms low -> 0.3ms high 0.9ms low
    (digital one) 0.56ms high 1.69ms low -> 1.3ms high 0.9ms low become like these
    What about the bit order
    Is it right ?
    Start bit (2) Manufactures Bit (12) Command Bit(8)
    Assume that manufactures number is 5 and command 17
    10 000000000101 00010001
  • 0 in reply to erdem simsek
    Guru 46710 points

    erdem simsek said:
    Now , (digital zero ) 0.56ms high 0.56ms low -> 0.3ms high 0.9ms low
    (digital one) 0.56ms high 1.69ms low -> 1.3ms high 0.9ms low become like these

    According to protocol - only low pulses are stretched, high pulses all are same duration.
    So you shall invert only pulses, not order of data encoding.

    You captured following:

    4.1 ms high
    1 ms low

    1.3 ms high
    0.9 ms low

    1.3 ms high
    0.9 ms low

    1.3 ms high
    0.9 ms low

    0.3 ms high
    0.9 ms low

    After inversion it shall translate to:

    x.x ms high
    4.1 ms low // start

    1 ms high
    1.3 ms low // 1

    0.9 ms high
    1.3 ms low // 1

    0.9 ms high
    1.3 ms low // 1

    0.9 ms high
    0.3 ms low // 0

    0.9 ms high
    [...]

  • 0 in reply to Ilmars
    Expert 2165 points

    Hi again me,

    I am comparing  samsung remote controller 's oscilloscope result and mine . Everything seem to be same . But i does not , I already tried 36kHz and 38 kHz . 

    Would you like to help me :) Where is the problem?

    The first picture is from Samsung Remote Controller  , the other's from mine

    Thank you for your helping

  • 0 in reply to erdem simsek
    Guru 46710 points
    Hi! Clearly visible that your wait duration differ.

    >I already tried 36kHz and 38 kHz .
    Don't try. Measure instead. - By connecting scope lo IR led of TV remote and yours.
  • 0 in reply to Ilmars
    Expert 2165 points
    Pwm output is already measured. I setted the wait duration according the samsung remote controller , it does not work (i don't know , ) Instead of it , I connected the P1.3 (button on msp430g2553 launchpad) . Now , i can use with button .
  • 0 in reply to erdem simsek
    Guru 46710 points
    >Pwm output is already measured.
    So why did you experiment using 36KHz and 38KHz then? - IF you measured IR modulation frequency of original remote. You just have to use same freq on your remote.

    >Now , i can use with button .
    So your TV receives commands now or what?
  • 0 in reply to Ilmars
    Expert 2165 points
    Yes , tv receives commands .
    I am sorry , while i was writing , my head was confused . It could not explain myself purely

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