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  1. #1
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    Pic to Pic rf communication circuit

    Hi all,
    I am new to this forum. Please help me. I am designing PIC-PIC connection using rf link. I am using PIC18F4550. Could u all please comment on the circuit I have attached. I don't know whether the circuit is correct or need some addition. Thank you



    my rf circuit.jpg
    Pin 25-->Tx
    Pin 26-->Rx
    Pin 13&14-->20MHz
    Pin 11, 32-->Vcc
    Pin 12, 31-->GND

    •   Alt18th February 2011, 02:19

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  2. #2
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    Re: Pic to Pic rf communication circuit

    What, specifically, is your question and problem?

    Your circuit diagram is... confusing and ambiguous. First off, what kind of transmitter and receiver are you using? Are you using the USART? The information you have provided is not enough to help.
    Chewie RFC
    KJ6MSG



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    Re: Pic to Pic rf communication circuit

    I want to know whether the connections of my circuit is correct or not.
    Basically, I want to do this type of connection.

    PIC--TX .....RX--PIC

    I want to connect both PIC using rf link.

    I used NT-T10A (433MHz) as my transmitter and CWC-12(433MHz)



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    Re: Pic to Pic rf communication circuit

    Since the tx and rx are not on your schematic its impossible to make a comment.
    The only thing I can say is make sure your tx and rx have power connected and that if they need one there is a pull up resistor on the input/output.



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    Re: Pic to Pic rf communication circuit

    Post your detailed circuit.. that will usefull others to help you...
    Anyhow your connection method is (PIC--TX .....RX--PIC) correct. but make sure about your Transmitter & recvr connecction..
    Senthilkumar.



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    Re: Pic to Pic rf communication circuit

    I am sorry for the inconvenience before. Hereby, I attach the circuit for my transmitter and receiver. Could u all please help me take a look at it and give any comments. Thank you.Transmitter.jpgreceiver.jpg



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    Re: Pic to Pic rf communication circuit

    Your circuit seems right... (except other part of circuits???) (Why switch & led? ) But if you provide more details about your application that ll be better to all to give suggt to you... Do u need 2 way communication? (ie.r u using both pic's for transmitter & recvr?) Which ic in pic family u hv used?
    Senthilkumar.



    •   Alt21st February 2011, 09:52

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    Re: Pic to Pic rf communication circuit

    I want to receive data from a sensor to pic 1. Then transmit it to another pic which is pic 2. I use pic18f4550. I think I have to use 2 way communication in order to ask pic 1 to transmit and stop sending data. Then from pic 2, i will connect it to max 232 then pc to display the data in GUI.



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    Re: Pic to Pic rf communication circuit

    Your schematics seems fine.
    You can use "Full Duplex" communication between the two controllers and implement something like a handshake. Or, you can use "Half Duplex" communication and in this case one controller will always send the data and the other will always receive the data.

    I still can't get where your problem is, the code, the schematics, the PC GUI...etc.

    Write your code and whenever you get stuck, post your problem.



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    Re: Pic to Pic rf communication circuit

    You need to ensure the output of the receiver is meets TTL voltage levels. you also need to ensure the output pins of the PIC is able to drive your transmitter input.



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    Re: Pic to Pic rf communication circuit

    hi guys,
    i have a problem..i connect my pic 2 to max232. it says that my max232 has floating input pins. i did not want to use that pin. i only use T1 in and R2 in. I left T2 in and R2 in unconnected. how do i solve this problem. it may be simple but please help me. thank you.



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    Re: Pic to Pic rf communication circuit

    Tie the not used inputs to ground and, left the output not connected.


    1 members found this post helpful.

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    Re: Pic to Pic rf communication circuit

    have a look at Serial Communication for max232 , I don't know how you implement encoding and decoding of your Rf signal in software maybe but the most of the rf circuits on the net use Holtek encoder and decoder chips between micro and rf module



  14. #14
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    Re: Pic to Pic rf communication circuit

    Hello a newbie here.
    I'm currently doing the same project as the OP but using a different microcontroller (PIC18F4520). My question is if the TX pin (RC6) is being used for the transmission and the RX pin (RC7) is being used for the reception for both PIC, if the RS232 is connected to the PIC 2, then can the PIC 2 send the data receive to the computer for display on the Hyper Terminal? I quite confused here since if the USART for both PIC are being used with each other, then how the second PIC will communicate with the computer.

    Thanks in advance.



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    Re: Pic to Pic rf communication circuit

    Hey guys,
    I would like to ask all of u to give opinion on my tx and rx code. I don't know whether it is correct or not. Thank you.

    1. tx

    #include <18F4550.h>
    #fuses INTRC_IO, NOWDT, NOPUT, NOBROWNOUT, MCLR, NOLVP, NOPROTECT
    #use delay(clock=8000000)

    #use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS, STREAM=PIN_A1)

    void main()
    {
    while(1)
    {
    getc(PIN_A1);
    delay_ms(20);
    putc('T');
    delay_ms(20);


    output_high(PIN_A1);
    delay_ms(100);
    output_low(PIN_A1);
    delay_ms(100);
    }
    }


    2. rx

    #include <18F4550.h>
    #fuses INTRC_IO, NOWDT, NOPUT, NOBROWNOUT, MCLR, NOLVP, NOPROTECT
    #use delay(clock=8000000)

    #use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7,parity=N,bi ts=8,ERRORS,STREAM=COM_A)


    unsigned int8 data;
    int1 flag=0;

    #int_rda
    void rd_isr(void)
    {
    //disable_interrupts(INT_RDA); // Disable Serial Recieve Interrupt
    //disable_interrupts(GLOBAL); // Disable Global Interrupts

    data= fgetc(COM_A);

    if(data=='T')
    {
    flag=1;
    }

    //enable_interrupts(GLOBAL);
    //enable_interrupts(INT_RDA);
    }

    void main()
    {
    enable_interrupts(global);
    enable_interrupts(int_rda);

    while(true)
    {
    if(flag==1)
    {
    output_high(PIN_B6);
    delay_ms(100);
    output_low(PIN_B6);
    delay_ms(100);

    flag=0;
    }
    else
    {
    delay_ms(100);

    delay_ms(20);
    fputc('T',COM_A);
    delay_ms(20);

    delay_ms(100);
    }

    output_high(PIN_B2);
    delay_ms(100);
    output_low(PIN_B2);
    delay_ms(100);
    }
    }



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