Hello all:
I've been working with PIC micros for a while, and am looking to get "untethered." I would like to transmit sensor data wirelessly over a distance of maybe around 20 meters, and possibly through (non-metallic) walls (and then maybe only 5 meters). The transmission would be one-way and relatively low duty cycle, at most several bytes (precoded) of sensor data once every few seconds. Since I don't need full-duplex, I could get away with simply an rf transmitter/receiver pair I think. Since PICs can handle RS-232 comms really easily, I was wondering if there are any inexpensive rf pairs that have built-in RS-232 comms support: Bacially, just write the data to be sent on the transmission side as if you were printing to the RS-232 port (the PIC Tx pin), and then on the receiving side just look for RS-232 data on the PIC Rx pin. Any fancy encoding required for the rf comms (like DC-free Manchester or whatever) would be transparent to the user, and coded/encoded by the transmit/receive modules. 1) Do such modules exist? I saw some describe in a Parallax Stamp app. note I think, but can't locate the modules in question. 2) Is the encoding/decoding overkill? Do I need DC-free codes for such low-duty cycle, low data rate channels? I thought that Manchester encoding was used when the clock needs to be embedded in the data; its not solely for the DC-free aspect. I am not experienced in this area, and when we covered it in school, I was sick that day..... Seems to me that getting the receiver "in synch" with the tramsmitter is much more important as far as reliable performance goes in the link I describe.
Any feedback suggestions links appreciated; I'll summarize my findings and report back.
Thanks very much, Bill T.