more RFM12 examples

Dave · Joined: 05 Feb 2005 Posts: 314 Location: McMinnville, OR

Here are three simple examples for getting started with the RFM12 transceivers.

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rileyesi · Joined: 19 Dec 2006 Posts: 398

Dave,

Where can you get this device in the USA?

Thanks,

Pete

Dave · Joined: 05 Feb 2005 Posts: 314 Location: McMinnville, OR

Pete,

For small orders you can try http://www.futurlec.com/Radio-433MHZ.shtml $8.90 for RFM12B. There shipping is a bit slow. Futurlec only carries the 433mhZ band and only the pin version (I prefer the surface mount module)

Or you can order direct from http://www.hoperf.com/rf_fsk/rfm12b.htm.
I paid $3 ea. a year or so ago for the 900mhz band modules. But shipping was $20 and slow. I ordered 10 so each cost $5 after shipping.

Also the RFM12BP has 500mW output. I have seen range of over a mile with these in the 900mhZ band. Legal in the USA but maybe not in other countries.

Dave

rileyesi · Joined: 19 Dec 2006 Posts: 398

Thanks.

bzijlstra · Posted: Tue Jun 29, 2010 6:58 pm Post subject: RFM12 and calculator...

Thanks for sharing. Looks very nice.

Here you can find a RFM12-calculator

www.technofun.org

Have fun
Ben Zijlstra

rileyesi · Joined: 19 Dec 2006 Posts: 398

Dave,

This is my first attempt at "making my own radio" and I want to be sure that I comply to all FCC rules. Can you point my feet in the right direction? I nosed around the FCC site, but was overwhelmed.

Again, Thanks.

Pete

Dave · Joined: 05 Feb 2005 Posts: 314 Location: McMinnville, OR

Pete,
Glad to help.
I googled "900mhz fcc rules". This link explains the rules regarding 900mhz band.

http://www.afar.net/tutorials/fcc-rules/

Dave

Dave · Joined: 05 Feb 2005 Posts: 314 Location: McMinnville, OR

I noticed something that was news to me in rfm12 chip data sheet today.

"Multiple byte write with Transmit Register Write Command:" thats the text and with that a timing diagram.

I don't know how I missed this before. I now send the rfm12 just one Tx command (B8 hex) and one chip select
for the whole message / packet. instead of for each byte. It's not much but it does shorten the Tx a little.

see attached code.
Dave

rileyesi · Joined: 19 Dec 2006 Posts: 398

Dave,

I shook the cob webs out of my head and found this:

http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf

It is titled, "Understanding the FCC Regulations for Low Powered, Non-Licensed Transmitters".

Thanks again for your help.

Regards,

Pete

Feruz · Joined: 23 Jul 2013 Posts: 2

Dave · Joined: 05 Feb 2005 Posts: 314 Location: McMinnville, OR

Feruz,

I could not find my original notes for this work so I made a quick hand cad drawing that I think will work.