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Thread: ARP : 38 Khz problem ....

  1. #1
    Administrator T-1000 vikas's Avatar
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    Default ARP : 38 Khz problem ....

    Hi

    What should be the best method for arp to generat 38 khz freq ( IR and sonar ) ...

    555 IC based : SImple frees precious CPU cycles can be easily extended

    uC based : Uses the uC ( extra processing ) but very accuarate

    4004 / 4081 gate based : Cant say much

    Also anyother method u know of ....

    Right now im thinging of putting in a 555 IC .... what do you say guys

  2. #2
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    Default

    555 with a variable potentiometer...
    if u put on a UC ,alot of pins get wasted doing nothing except generating pulses..

  3. #3

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    Hi
    A good robot has uC to control it. We don't need to fire sonar sensors all the time. few milliseconds per second is enough. only one pin is needed per sonar sensor. it is accurate. if we use 555 timer then we need to have CRO or frequency counter/meter to set it to exactly 38KHz. when we use a uC in robot, 555 timer ic is extra burden. we can use simplest uC like pic16f84. we can add lot of feature. after all nobody is going to build only sonar firing circuit or ir transmitter circuit. comments are welcome.

  4. #4
    Administrator T-1000 vikas's Avatar
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    Default Hi

    Well 555 based 38 Khz is not that difficult . Ill stick with it i think

    No io lines wasted
    No time critical assembly code
    Such code has difficulty in RTOS's

    also 38khz is too often used ... Sonar , IR Obstacle , IR comm etc .

    Adding 5 - 6 discrete components wont make the circuit complicated

  5. #5
    Senior Member Cyborg
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    Default

    well ya, 555 based 38Khz generator are pretty cool.....
    Sumandeep Banerjee
    M.Tech, IIT Kharagpur,
    B.Tech, IIT Kharagpur,
    http://www.robotix.in

  6. #6

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    I recommend using the PWM module of uC.. doesn't cause any load on uC.. accurate freq. and error free. The problem of using 555 is, its accuracy and the difficulty associated with its tuning and all.

    Regds

    happy_99

  7. #7

    Default

    555 is not accurate

    i think u won't be able to detect correctly 38khz in CRO

    if u use uC then it will be more accurate

    is there any need to be dutycycle=50%

  8. #8
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    Default

    i think using a 555 timer is not gud for this.....
    its difficult to get exact 38khz....
    using uc is a better idea....
    u avoid using big ckts,resistors,caps... etc and other components...
    so use a uc...
    if u thought u r the only mad person on the planet.......u got serious competition here

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