AT90S2323 Microcontroller 418MHz RF Transmitter 2 Channel
The transmitter is constituted by AT90S2323 microcontroller and TLP434 RF transmitter module at 418MHz. I have designe the transmitter for more battery economy and safe transmition of the data.
* The battery economy is made it by the use of powerdown mode of AVR. In this case the AVR goes to sleep with less than 1uA (microampere) current and wait for external interrupt on pin PB1 to awake from sleep and continue operating.
If you press the S2 key, the logic of this pin goes to ‘0′ (0V) and AVR awake frome the sleep mode (because PB1 is INT0) and check if pressed the S1 key. If not, the AVR take as pressed key the S2. If yes the AVR take as pressed key the S1.
If you press the S1 key the logic of this pin and PB1 (through 1N4148) goes to ‘0′ (0V). In this case the AVR take as pressed key the S1.
After, calculate the checksum and transmit 4 times the same 4 byte sequence to make sure that receiver takes the data and goes to sleep mode until next interrupt on PB1.
When the INT0 pin (PB1) of AVR goes to 0V, the transmitter TLP434A is working. If you stop press the switch S1 or S2, the TLP is stop working.
* The safe transmition of the data based to transmition of 4 bytes with serial form at 2400 bps (bits per seconds). 1st and 2nd byte are for recognition of valid remote control from receiver (like ID bytes), 3rd byte is command byte. The relays status dependet by the value of this byte. Finaly, the 4th byte is the checksum of the earlier 3 bytes.
example: if byte1=30h, byte2=35h and byte3=02h the 4th byte (chechsum) will be (byte1) XOR (byte2) XOR (byte3) = 30h XOR 35h XOR 03h = 06h.
This method use 4 bytes x 8 bit each = 32 bit length (without start and stop bits). That is mean 1 possibility at 4.294.967.295 to receive the receiver, the same 4 bytes from some other RF device.
This transmitter will work with all 2323 chips but better is AT90LS2323 with working voltage 2.7 – 6 volts.The microcontroller that I use is AT90S2323 with working voltage 4 – 6 volts. Its worked fine with 3v lithium battery.
