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Parallax 433 MHz RF Transciever with PIC16F877 — Parallax Forums

Parallax 433 MHz RF Transciever with PIC16F877

SajiSaji Posts: 3
edited 2010-07-04 17:27 in Propeller 1
Heyz, i need some help in connecting the parallax 433 mhz rf tranciever with the pic16f877 microcontroller (circuit diagram & the ccs) in Port A or C, i've done connectin the LCD and the 4*4 keypad, and i'm supposed to send some digits been entered by the keypad to another rf transciever connected with the PC(visual basic software)....

semi-block diagram:
_________________________________________________
··············································································|
Microcontroller >>> RF Trnscvr· ~ ~ ~ RF Trnscvr >>> PC |
_________________________________________________|

the string is like:

··· *12345*0000*50*54321

Thank you
·

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-07-04 16:36
    We can't help you with the PIC programming. This is a support forum for the Parallax Propeller microcontroller. A question like this could be posted to the Sandbox forum here, but we still can't help you with the PIC stuff. The RF Transceivers can be connected to pretty much any microcontroller. You do need to operate the Transceiver at the same voltage as the microcontroller (3.3V or 5V).

    There is sample code for using the Transceivers with a Stamp. See the links on the Parallax webstore product page. If you're knowledgable about PIC programming, you should be able to translate the sample code.

    On the PC side, you'll need some kind of interface. Since there's a bidirectional data line and a direction line (transmit / receive), you'll need more than just a simple serial voltage interface or serial to USB adapter. You may be better off with a pair of xBee transceivers. Parallax has a USB adapter board available that can just be plugged into a PC for a wireless serial link and, on the PIC side, you'd just need 2 I/O pins, one for transmit data and the other for receive data. The xBee takes care of error detection and correction. For simplicity in establishing a point-to-point wireless connection, use the Series 1 xBees.

    Post Edited (Mike Green) : 7/4/2010 4:49:45 PM GMT
  • SajiSaji Posts: 3
    edited 2010-07-04 17:17
    thank you mike, so am i unable to connect the transciever directly with the PC using the serial port?

    also, in the pic16f877 there are individual pins for Tx and Rx, and on the transciever side there is only one pin used for both Tx and Rx (Tx=high, Rx=low), how i'm goin to cennect the pins?
  • Mike GreenMike Green Posts: 23,101
    edited 2010-07-04 17:27
    1) The PC's serial port uses RS232 voltages which can be anywhere from -15V to +15V. This would destroy the Transceiver. A MAX232 would convert these to 5V/0V if you run the Transceiver off 5V. The MAX3232 works for 3.3V. Neither one would do the signal routing needed for the T/R line and Data line. You'd need some external logic and you'd manage that using the RTS signal from the PC.

    2) On the PIC side, you'd have to have at least a dual open-collector/drain buffer controlled by a 3rd I/O pin that would control the T/R line of the Transceiver and the active direction of the buffer.

    3) Again, I think you'll have an easier time with the xBee. Parallax has already done the work on an adapter for USB that even provides power to the xBee. On the PIC side, the xBee should directly connect to the PIC's Tx and Rx pins, at least at a 3.3V supply voltage. You'd need some kind of level translator if you're running the PIC off 5V. Parallax does have an adapter board that will handle that.

    Post Edited (Mike Green) : 7/4/2010 5:35:14 PM GMT
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