RF Transmitters/Receivers Arrived
Those RF units I was talking about in the previous post arrived today. Since the transmitter and receiver are actually separate devices, I ordered two sets at different frequencies for the robot and computer to communicate. One set is 433MHz, the other set is 418MHz.
These things are very small, and after playing with them, they seem to be on par for $12 per transmitter and receiver pair–even though they have a maximum speed of 2400 bps. I hooked up the transmitter to an AVR microcontroller (ATTiny2313) that was sending A’s straight out of the UART port. I hooked up the receiver to max232 serial module which was connected to my computer through a serial->USB converter. When the transmitter isn’t transmitting, the receiver picks up junk data that is floating around. With the AVR sending A’s though, I could see a fresh, clean stream of A’s coming in with the transmitter and receiver about 10 inches apart. It simply worked out of the box. More distance between the transmitter and receiver required some sort of an antenna, so I just plucked a 5 or something inch wire with the transmitter, and the receiver picked up the A’s from all the way across my room (it probably could have picked up from even further).
Here are some pictures of the devices:
Transmitter hooked up to the AVR, and the receiver hooked up to the serial port:
Close up of the transmitter device:
Close up of the receiver device:
Both sets of transmitters and receivers, with a quarter to show relative sizes:
