NRF24 / RFM69????
-
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)
@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.
-
-
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
I meant a 3,3V output, not a 3,3V working voltage. (Sorry I didn't mentioned that)@manutremo
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.@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. -
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...
I'm unaware of other cheaper solutions but some chinese manufacturer may have already launched something...
-
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.
-
-
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
