How to remove noise/false output of A434 RF receiver- interfaced with AVR UART

Discussion in 'Embedded Systems and Microcontrollers' started by priyersi, Jun 19, 2013.

  1. priyersi

    Thread Starter New Member

    Feb 25, 2013
    7
    0
    Hi all,

    I am trying to interface A434 RF module with Atmega8 . I made two circuits one is the transmitter and other is receiver.Now the problem is that even if i turn off the transmitter there is some noise output at the receiver side. Because of this my uart gives interrupts (i am using interrupt on reception complete) always. I want to stop this interrupt on false data. Can any one suggest me a way ?

    Many thanks in advance
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,145
    1,791
    I suggest you look a bit deeper into the source of the interrupts. Most UARTS have multiple conditions that will generate an interrupt. Are all of them except Rx Buffer Full disabled. Next Rx Buffer Full interrupts will only occur if there is a character received at the correct baud rate with a START bit, some number of data bits, and one or two STOP bits. Most UARTS will detect false START bits and not transfer data from the Rx Shift Register to the Rx Buffer unless some fairly stringent conditions are met.

    If you suspect noise on the receiver input you can always ground the antenna input. This won't hurt the receiver and we live in an incredibly rich RF environment. The tools you need to establish the presence of noise that is sufficient to look like characters would cost more than most people earn in year, so I would look for alternative explanations.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    The receiver will output garbage when there is no signal.

    Your interrupt needs to keep clearing the incoming bytes and/or error codes, until it finally detects the correct incoming sequence of real data.
     
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