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Support Forum » 315Mhz Rx and Tx using two MCU

December 26, 2011
by ese
ese's Avatar

http://winavr.scienceprog.com/example-avr-projects/running-tx433-and-rx433-rf-modules-with-avr-microcontrollers.html

http://narobo.com/articles/rfmodules.html

I've been using these two examples.

Using NK uart_read() and uart_write(). MCU1 transmits and MCU2 receives. If I wire the TXD pin of MCU1 to the RXD pin of MCU2 data is transfered. When the Tx and Rx are used transfer data packets are not recognized, but the receiver software is getting into the interupt handler.

December 27, 2011
by ese
ese's Avatar

http://extremeelectronics.co.in/rf/rf-communication-between-microcontrollers-part-i/

So I'm looking at the above reference. I then transmit simple packets of the same character (12 Ox55 characters). Still, although something is activating the receiver interupt handler, no Ox55 characters are recognized. I decide to put one end of antenna in rx and one end of same wire in tx thinking I can't get any better reception than that (from the mind of babes). In so doing, since neither the rx or the tx antenna was long enough for the purpose I decide to put on an extention plugging into the breadboard. Now here is the thing! When the other end of the tx antenna was put into the breadboard the receiver interupt handler started to recognize Ox55's and other garbage characters.

December 27, 2011
by ese
ese's Avatar

I've hooked up the tx_MCU to a keyboard as per NK. When a character is input from the keyboard a tx_subroutine sends that character out with more than 100 uart_write() calls. The receiver MCU recognizes just a few ( less than 10 ): interupt driven or polled.

It is fun to know that action at a distance is happening.

The rx_MCU is constantly busy with uart_read() calls. Test code puts out these characters to my laptop via usb_serial cable and Python as per NK. The character of these characters (how's that) changes if the tx is switched off.

If the tx_MCU_software is put in a loop to constantly put out a character the rx_MCU_software puts out almost no garbage, but it doesn't capture all that comes from the tx.

December 27, 2011
by ese
ese's Avatar

The tx_MCU_software is put into a tight loop putting out a ' ' character until the char_waiting flag goes low indicating there is input from the keyboard. Then the incomming character is put out.

On the receiver side there is no garbage at all. Still there are only a few transmitted characters displayed, but they are all the right character.

December 28, 2011
by ese
ese's Avatar

Is this entrainment?

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