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  1. #1
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    interfacing i2c 3.3v device with a PIC of 5v

    Hello all

    my Microchip pic 16F877 uses 5V Vcc,

    and i need to interface it with my i2c ambient light sensor which use 3.3V Vcc.

    my questions are:

    1. Does the PIC and light sensor can commuincate or since they have differnte logic levels its not possible?

    2. what about the NXP PCA9512 levelshifter component ?
    can it do the job? does it work? do i need it?

    attached:

    NOA1302 light sensor.
    PIC16F877 Micro.
    NXP level shifter.


    Thanks,

    amico.

    attached

    •   Alt2nd March 2010, 13:53

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  2. #2
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    Re: interfacing i2c 3.3v device with a PIC of 5v

    Please check the logic levels in the datasheet and you'll see that it doesn't work. So you'll need levelshifter.
    Btw. there's a nice application note from NXP/Philips about that using FETs only:
    http://ics.nxp.com/support/documents...df/an97055.pdf



    •   Alt2nd March 2010, 14:16

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  3. #3
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    interfacing i2c 3.3v device with a PIC of 5v

    Thanks for the answer.

    can I trust the NXP PCA9512 level shifter to do the job?

    does anyone have any experience with this component or can recommend another level shifter for my application?

    Thanks.



    •   Alt2nd March 2010, 14:21

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  4. #4
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    Re: interfacing i2c 3.3v device with a PIC of 5v

    Hi! I've just had got that problem in my final degree project, and I've applied that solution:

    http://www.neoteo.com/adaptador-de-n...2c-3-3v-5v.neo

    I'm using a IRF510S as mosfets, but you can use other one. It's working, and I can see the bus pulses in a oscilloscope:



    Good luck! :)



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