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Communication of TRW-24G RF modules with AT90S2313 microcontroller

Communication of TRW-24G RF modules with AT90S2313 microcontroller

This modules working at 2.4 GHz frequency with GFSK modulation, and the data-rate is 250Kbps and 1Mbps.
My circuit is constituted by 2x TRW-24G modules, 1x AT90S2313 microcontroller and 1x MAX202 TTL to RS232 voltage level converter. The RF modules work with +3.3V not with +5V. I connect this modules to STK500 development board and I set the VTG voltage to 3.3V from programmer’s software in AVRstudio. For serial communication I used the internal MAX202 of STK500 board, that is working at +5V power supply. There is no problem with that, but the AT90S2313 MUST be work at 3.3V or else you will burn the RF modules if you send +5V instead +3.3V (max. 3.6V).



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When you power-on this circuit, the AVR it will configure the IC1 as receiver and IC3 as transmitter. Then, the AVR it will check the DR1 pin of IC1 for incomming data. If DR1 pin of IC1 is LOW (logic ‘0’) the AVR it will send serial from IC3 the 5 byte address of the module that is want to send the data (AA,BB,CC,DD,EE hex address) and the Payload bytes wich is the data that it want to send (31,32,33,34 hex, are the same as 1,2,3,4 ASCII). When AVR push the CE1 pin of IC3 to LOW (‘0’) the IC3 transmitt the data with baud rate of 250kbps (i set the communication to 250Kbps not to 1Mbps). After some small delay, the AVR is going to read again the DR1 pin of IC1 for incomming data. In this step the DR1 pin of IC1 is going to logic ‘1’ because receiver’s buffer now have the 4 bytes (payload bytes) that we have transmit before with IC3. The LED1 it will flash for a moment to show that the receiver’s buffer have incomming data. Then, the AVR it will read this 4 bytes and send them serial via PD1 and MAX202 to PC with baud rate 9600bps/8/n/1. When AVR read all data from IC1, the LED1 it will turn-off.

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