NRF24 / RFM69????

  • Hi All,

    I'm a new-bee and just started my home automation with an RPI B and an el cheapo RF and TX module combined with some scripts I'm able to switch my lights on and off (using sun up/down with interval time and darkness/cloud sensor) I just bought some smoke detectors that are compatible with Domoticz but whatever I try I cant see them?? after some reading here and on other forums I guess that it is useful to build a Gateway / RFlink to send and receive data and connect temp/hum/sun/door/PIR sensors with the RPI.

    My question now is what should I choose?? NRF24 or RFM69 or an RFlink, and Why??

    Thanks for your input.

  • Hardware Contributor

    @Roloz - they all have its + and -.
    I use it like this:

    MySensors Nrf24: My default radio, cheap but might need some work sometimes to get it to work - DIY
    MySensors RFM69: More expensive radio and also DIY but I find it a bit more reliable. I use this mostly for long range like garden and outdoor.
    RFLink: I use this to switch my AC mains, because then I can buy switches (433mhz) which are approved to switch main power. This only because of safety.

    Note that RFLink isnt MySensors so you need a RFLInk gateway for that one.

  • Mod

    I'd add that RFM69 driver can adjust power output automatically and it makes it easier to install as you don't need to find the best power level in order to save battery and you can also report to controller che signal level if you need to know if it is strong enough; the downside is that they are strictly 3.3v so you need either an arduino pro mini 3.3v or raspberry to use them without a logic converter.

  • @sundberg84 My 433Mhz Rx with external antenna (17cm wire) has a limited range, it only sees signals from my KAKU remote within 15 cm (max), my Tx is working good, I can send the signals from the living-room to the addict (about 8mtr higher trough 2 concrete floors) and the garden. So switching on my AC Mains works good, but receiving signals from the doorbell and the smoke detectors doesn't work at all.
    Do you have any experience with receiving signals?? Do you use the RFLink or the RFM69 for this.
    And how many work do you have with the Nrf24, I thought of using it to get Temp/Hum and light info from every room and switch the lights and on sunny days to open or close the shutters (trough the same Nrf24), is this a good or bad idea?? (also want to use it to send info back if the signal is received)

    @gohan Oke thanks for your info, I forgot that the RFM69 is only 3,3V and you will need a converter. I'm planning to use all the modules with a power adapter so battery saving is no issue.

  • Mod

    You don't really need a converter, you can just use a pro mini 3.3v or an esp8266.

  • I hope/thought that an Arduino NANO has also 3,3V. (this because I ordered 3 of these Arduino's to use for starting with MySensors)

  • Mod

    I am not aware of a 3.3v version of Arduino NANO

  • @Roloz I guess you are refering to the 3.3v output on the Nano. There are two issues with this:

    • the Nano IO ports are still using 5v levels. Nrf24 is 5v/3.3v tolerant, but rfm69 is not, so you will need to use a converter.

    • if you are using one of the high power versions of the rfm69 and using the high power settings, the Nano might not be able to provide the necessary power.

    If rfm69 is your choice (it is mine) using a 3.3v mini pro really simplifies things.

  • @gohan
    I meant a 3,3V output, not a 3,3V working voltage. (Sorry I didn't mentioned that)

    Oke, why is the RFM69 your choice?
    Do you also use them for sensors (temp/hum/lux/smoke detector) or to switch AC Mains/Modules.

  • Mod

    I can tell my preliminary findings in comparing nrf24 and rfm69 in my house: nrf24 gateway uses the PA LNA with a long antenna and node uses a standard module all set to max power, the rfm69 433mhz performs better using less power

  • @gohan

    Thanks for your input, A good reason to go for the RFM69 module. I will try to change the Arduino nano for the mini pro and use them with the RFM69. 👍

  • @Roloz My first choice was nrf24. I found multiple problems with; even after all the power feed, etc issues had been solved, some sensors were still showing very unstable connections.

    I finally built a "nrf24 scanner" and found that I had problems of coverage. I tested many combinations of power settings between the gw and the sensors, but was unable to find one that worked for all sensors. If I pushed the power high, the sensors positioned further got good connection, but the closest ones became saturated and failed. With lower settings, the closest worked but the farthest didn't. My home is small and there aren't too many walls; probably the 2.4GHz band is just quite saturated.

    I finally decided to try the rfm69hw and found it more stable. I also migrated to the new development branch which supports automatic power setting and found this helped a whole lot. I had to lower the gw transmission power from the default 20dB to 0-5dB, which means that I should have been fine with non-hw modules, but the price difference is not that high and who knows some day I may need the additional range.

    Just one additional comment - If you are ever using the hw version at full power, keep in mind that the arduino 3.3v vout may not be able to provide the necessary power to the rfm69 module, so you might need to power it separately so it's fully reliable.

    I hope this helps.

  • @manutremo
    Thanks for your input, this is very helpful information for me.
    I will start with the RFM69 modules in stat of the Nrf24.

  • Mod

    @Roloz just be advised as rfm69 are a bit more of a hassle due to the need of the pcb since they are smd

  • Not necessarily - I 've been using the rfm69 boards welding wires directly to the board with no problem. Recently I started to use JST PH 2.0mm connectors with good results too.

  • Mod

    Soldering wires directly for me still stands in the "hassle" category 😌

  • Certainly not as easy as just inserting the pins - but certainly less than building a PCB.

    However in that case the adafruit and sparkfun versions come already soldered to a PCB with standard 2.54mm holes... significantly more expensive (3x-4x) and you still have to solder the pins anyways...

    Adafruit RFM69

    Sparkfun RFM69

    I'm unaware of other cheaper solutions but some chinese manufacturer may have already launched something...

  • Mod

    There are multiple pcb solutions for rfm69 on that you can still have for quite cheap.

  • Interesting site, thanks. I searched RFM69 and checked on some of the results. Only some of the results seem to be rfm69 modules (most are complete nodes, gateways...). The minimum purchase quantity seems to be 10units and with the delivery cost the cost is closely the same to that of the usual rfm69 modules. Some of them seem to come unassembled. However some might be interesting for some of my upcoming projects. Which one(s) would you recommend that includes rfm69 (+ power voltage limiter + level converter if possible) and is ready for connecting the wires with no soldering?

    The "hassles" I see with the rfm69 vs the nrf24L01 (apart from soldering if that's not your piece of cake) are:

    • The max power voltage is 3.6v (3.9 absolute maximum). That means that if you want to use i.e. Li-ion batteries (which are 4.2v fully charged), you need to limit the voltage so that it stays below 3.6v. I use a HT7350 or a MCP1700-3302E for that. The nrf24L01 doesn't need that unless you use a higher voltage source.

    • The RFM69 pins are not tolerant to 5v TTL levels as the nrf24L01 are. Again, if you are using a 5v arduino board, you'll need some levels converter.

    Overall, it's good to see that there are many options available, the user just needs to select the one that best fits the specific application.

  • Mod

    From openhardware you can download the Gerber files and have them printed from your favorite pcb factory. As you may have noticed the pcbs supporting rfm69 do usually have a pro mini 3.3v socket. For nrf24 you still can't use lipo batteries without a ldo voltage regulator. Personally I'd prefer the rfm69 as you can choose the frequency you prefer while the nrf24 are stuck to the heavily crowded 2.4Ghz

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