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Topic: very impressed with RFM69HW module for wireless (Read 628 times) previous topic - next topic

arusr

Apr 19, 2014, 11:03 pm Last Edit: Apr 20, 2014, 02:15 pm by arusr Reason: 1
I did some experimenting with RFM69HW modules.  Very impressed with the distance!  Using two RFM69HW modules, I was able to get pretty good communications up to 4 houses away (your typical quarter acre suburban lot).  So the signal was going through my house to the outside, 4 houses away, and THROUGH another of my neighbor's house.  I didn't have any debug code in there to see if I can analyze the number of retries.

Using two nRF24L01 (one of the regular low power one for transmitting, one high power one for receiving, which may not be the best setup), I was able to get good communication up to the end of the house in the third bedroom.

Keep in mind also that I didn't do anything special with antennas.  I'm using a dupont wire, 20cm long.  The RFM69HW module I have is 915Mhz.  It's nice that it doesn't interfere with wifi, and wifi doesn't interfere with it.

robtillaart


how much in 4 houses away?

living in a flat or in a rural area we are talking quite different distances  ;)
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

arusr



how much in 4 houses away?

living in a flat or in a rural area we are talking quite different distances  ;)


At least 200ft, through a couple walls.

serg10

I'm sure you could get even more power with an antenna!

How are these to work with? are they easier than the nrf24?

arusr

#4
Apr 21, 2014, 02:34 am Last Edit: Apr 21, 2014, 02:38 am by arusr Reason: 1
The nRF24L01 comes with dupont wire friendly pins.  The RFM69 do not.  You have to do some soldering.

I've found that using 22 gauge wire and soldering them onto the RFM69 is the easiest way.  I've tried male pins with the 2.0mm pitch and matching female dupont cables, but the connections are shaky.  Best to just solder wires directly.

For my projects, I've decided to go with these RFM69 modules.  No interference from wifi.  Better wall penetration, goes six times farther.  The high gain (20dB) version of the RFM69 is cheaper than the high gain version of the nRF24L01.  I don't know much about antenna design, but a simple 22 gauge wire about five inches long does what I need.

I haven't gotten around to implementing what I want to do with them.  Need to figure out how to pass along a user defined struct.

robtillaart

Quote
I haven't gotten around to implementing what I want to do with them.  Need to figure out how to pass along a user defined struct.


you should address the struct as an array of bytes, so you can do

Code: [Select]
RFM69HW.write(&struct, sizeof(struct));

assuming the class has a write(byte array, len) function.
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

MarkH

Which library did you use for the RFM69HW?

I'm trying to use the RadioHead library but I keep getting a momentary connection and then it stops.

Any chance of sharing your code?

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