PIC16F84 RF howto

[Matt(Pic progger)]

Hmmm, I think I may know what you want, do you mean.......

1:Send a radio signal to a base(s) to say "I am going to send and ultrasonic pulse"
2:Base(s) then listen, and time the period to get that pulse, and so knows the distance to the base?

I think the speed of sound is 340.29 M/s in air at sea level so you should be able to calulate this. BUT there is a small problem Radio modules can have a variable delay from TX to RX, I know because I code for them, alot, this can vary up to 10uS depending on modules etc.... so you will have to take this into account.

Anyway, this sounds an interesting idea, how can we help? (If I have go the right end of the stick!)

 

[TiagoSilva]

To the base ?! I thought you were using it just to avoid obstacles, and to process the signals right on the robot ..., i have a better way ... Have an RTC mixed with the microcontroller board and send the clock time with the transmition, but you must syncronise the time at the base receiver with the RTC on the robot ! You need to use an accurate RTC with sub-seconds capacity ... This way you don't need to worry with data loss or anything else because you know when it was broadcasted it's simpler and better ! Oh, since you are using to broadcast to the base try using some bluetooth modules as RF transcenders if you have time to learn how to use them of course ... they have 1Mbit data rate or so ... have a check, this is if your base is the computer ...

 

[dlconejos]

Thank you, very very much for your reply sirs. Actually, i would like to implement wireless sensor nodes using PIC16f877 place on each nodes. Each node will also have a TX/RX ultrasonic and RF. The sequence will follow [ i hope this is correct]:

1. A single node [ NODE A ] will be attached to the PC via RS232.
2. When the other nodes are placed along with NODE A, it will give a real time simulation to the PC, showing the localization of all the nodes present.

But i planned, not to have a predefined location of all the nodes such that these nodes can locate themselves using TDOA or TOA theory.

I have seen it at MIT using Cricket that is really working. But I like to implement it using PIC.

i hope you can help out...