Three RF transmitters?
MJHanagan
Posts: 189
Hi All - I have an application that will require three individual RF transmitters (something like the Linx Technologies CMD-KEY5-xxx keyfobs) all "talking" to a Propeller or Stamp micro. Each keyfob has 5 keys on it so when a key is pressed the fob transmitts its "ID/Address" and some number corresponsing to which key is pressed (presumably something like 1, 2, 3, 4 or 5). The Linx RF receiver (RXM-xxx-LR) demodulates the RF signal from the keyfob transmitter and sends out a "data" stream which can then be converted to an RS232 data stream using something like a "MAX232". Now presumably the CMOS data stream output from the receiver contains the fob address and the key data.
They also show how you can demodulate the receiver's output using a decoder wherein an output pin on the decoder corresponding to the key being pressed goes high. However, if I do it this way I would need three such decoders (one for each keyfob address) and then I would have to use 15 I/O pins on the Propeller/Stamp just for the RF signals where as if I can utilize the data stream from the receive then I should only have to utilize one I/O pin for the RF signals.
If so my question is as follows:
Do I need to feed the data stream from the RXM receiver through the MAX232 converter before I input it to the Propeller/Stamp or can these micros handle the CMOS output directly from the receiver? And is the Propeller/Stamp capable of "reading" the incoming stream of data and processing it reasonably fast?
They also show how you can demodulate the receiver's output using a decoder wherein an output pin on the decoder corresponding to the key being pressed goes high. However, if I do it this way I would need three such decoders (one for each keyfob address) and then I would have to use 15 I/O pins on the Propeller/Stamp just for the RF signals where as if I can utilize the data stream from the receive then I should only have to utilize one I/O pin for the RF signals.
If so my question is as follows:
Do I need to feed the data stream from the RXM receiver through the MAX232 converter before I input it to the Propeller/Stamp or can these micros handle the CMOS output directly from the receiver? And is the Propeller/Stamp capable of "reading" the incoming stream of data and processing it reasonably fast?
Comments
The Parallax 433MHz transceiver #27982 is built around the Linx TRM-433-LT, and it is perfectly possible to interface it directly to the Propeller using two I/O and a resistor, and the Propeller handles the signal rate with flying colors.
Edit: And you only need one transceiver to receive all the transmitters.
Thank you for the help!