Project

General

Profile

RFM69 on Raspberry Pi

Added by mvdswaluw almost 4 years ago

Is there a command calculator for the RFM69? Like [[[http://tools.jeelabs.org/rfm12b.html]]] for the RFM12B.


Replies (17)

RE: RFM69 on Raspberry Pi - Added by jcw almost 4 years ago

I haven’t found one yet, unfortunately.

Setting one up is a fair amount of work, especially with the RFM69 which has even more registers than the RFM12.

So far, I’ve been leafing through the RFM69CW and SX1231H datasheets to figure out all the settings.
Many further tweaks are still possible, I expect.

RE: RFM69 on Raspberry Pi - Added by mvdswaluw almost 4 years ago

jcw wrote:
> Many further tweaks are still possible, I expect.

That’s why I asked ;-)

RE: RFM69 on Raspberry Pi - Added by arthurjw almost 4 years ago

I am having difficulty compiling the MQTT example. I get the following error message:

make
g++ -I../../../lib/arch-raspi -I../../../lib/driver rf69mqtt.cpp -lwiringPi -lwiringPiDev -lpthread -lmosquittopp -o rf69mqtt
In file included from rf69mqtt.cpp:28:0:
/usr/include/mosquittopp.h:45:23: fatal error: mosquitto.h: No such file or directory
compilation terminated.
: recipe for target ‘rf69mqtt’ failed
make: ***** [rf69mqtt] Error 1

I have followed the instructions and installed the developer files. I am not a Linux expert. Any ideas?

Also the pinout for the expansion header is incorrect. Pin 14 should be labelled Pin 16. My first try (on a PI 2 which has more pins) was displaced by a row and obviously didn’t work. No harm was done and it functions correctly on the correct pins!

RE: RFM69 on Raspberry Pi - Added by jcw almost 4 years ago

> Also the pinout for the expansion header is incorrect. Pin 14 should be labelled

Whoops. I’ve fixed the article diagram. The pins involved are: pins 15 through 26.

On a 40-pin header, it’s the middle 6 double rows. On a 26-pin header, it’s much easier, i.e. the far end.

> /usr/include/mosquittopp.h:45:23: fatal error: mosquitto.h: No such file or directory

Ah, wait - I used Odroid w/ Ubuntu, on Raspberry Pi w/ Rasbian you also need this:

sudo apt-get install libmosquitto0-dev

RE: RFM69 on Raspberry Pi - Added by arthurjw almost 4 years ago

Thanks. It compiles now.

RE: RFM69 on Raspberry Pi - Added by tht almost 4 years ago

Just wondering if it should not be possible to power the RFM69HW using the 3V3 pin. Sure current is a problem. But why not put a kinda big cap directly in front of the RFM69HW and use a series resistor to connect them to the 3V3 pin?

I’m probably missing something here… But wouldn’t a 66 ohm resistor limit the current to the cap to 50mA but slowly fill it up to about 3V3? As the RFM69HW’s duty cycle is quite low this should easily keep it up at >3.0V. Some energy may flow through the GPIO pins but some small resistors should solve this one too.

I never got the range I needed out of RFM12B modules, so I’m looking for as much “spare” range as possible when starting to build something new.

RE: RFM69 on Raspberry Pi - Added by JohnO almost 4 years ago

Good to see you back @tht.

RE: RFM69 on Raspberry Pi - Added by martynj almost 4 years ago

tht,

The trickle in/gulp out approach is feasible - the cap size needed to limit the transmitting drop to say 3.3v > 3.0v for maximum power and maximum packet length is not too huge.
Remember the power-off case though
the poor LDO feeding the 3.3v will end up with 0v on its input pin but the charged capacitor value on its output pin. Different LDO designs handle this case differently (and not often described in the spec sheet). This state can happen anyway with lots of decoupling capacitors on the output pin and a low energy store on the input side, but this is relatively brief waiting for some 0.1uF caps to discharge compared with the many uF required for your idea.

Since the range is determined by the entire loop S/N ratio budget, provided you have a ’quiet’ RF background that allows use the full sensitivity of the receiver section, pushing the Tx power up into the boost range may not be required. Note that an RFM69HW with just PA1 running is equivalent to the RFM69©W.
An early check of the background RF level when installed in the Raspi environment is worthwhile.

RE: RFM69 on Raspberry Pi - Added by tht almost 4 years ago

@JohnO:
Thanks – I was following jcw’s blog all the time but I’m kinda in a waiting state. Still unsure which route to take for a restart of my home-monitoring/automation system. Great ideas everywhere but also too many open ends for me to make a decision. I’m clearly not asking for a turn-key solution but the basic building blocks should be available.

@Martynj:
Yeah, the power-off case. I was thinking about this one too. An “ideal” diode would be great but too much of a hassle as a 5V pin is readily available. So adding a separate LDO would probably be a better/easier way.
Are you talking about the RF noise from the RPi itself? Adding some basic shielding should be possible. I’ll probably start doing some (basic) range tests with a RFM69W module on a RPi myself but it’s good to know that there’s a more powerful module available if needed. Still trying to reach the mailbox two floors below (thick walls, thick flooring and an elevator shaft – don’t ask…). Thanks for your feedback.

RE: RFM69 on Raspberry Pi - Added by jcw almost 4 years ago

A high-power variant of the RasPi RF sounds like a good idea for when range is an issue, but I’m not sure it really will help if only the central node switches to the H module.

RE: RFM69 on Raspberry Pi - Added by tht almost 4 years ago

jcw wrote:
> … I’m not sure it really will help if only the central node switches to the H module.

In my understanding it’s only the TX-part which is different. So the sending node actually has to be the H version. My ideas for a higher-level rf network protocol actually need two-way communication anyway. So if range is an issue, I’ll have to replace both nodes.

RE: RFM69 on Raspberry Pi - Added by jcw almost 4 years ago

It’s not much, but I have 4 prototype RasPi RF boards left to share. If you plan to do something with an RFM69 or RFM73 connected to a Raspberry Pi in the very near future and let me know by email along with a postal address, I can send you one of those PCBs.

RE: RFM69 on Raspberry Pi - Added by tht almost 4 years ago

jcw wrote:
> If you plan to do something with an RFM69 or RFM73 connected to a Raspberry Pi in the very near future and let me know by email along with a postal address, I can send you one of those PCBs.

Thank you for this offer. I’ve not yet decided which architecture or programming framework to use in the future but RFM69 and also RPi is kinda set. I’ll send you an email tomorrow.

Is there any reason NOT to buy the HW model? The store I buy these RF-modules from charges exactly the same for RFM69W and RFM69HW.

RE: RFM69 on Raspberry Pi - Added by JohnO almost 4 years ago

The W & HW have a 16 pad wafer versus 14 pad. Obviously only an issue if using the PCB from @jcw.

RE: RFM69 on Raspberry Pi - Added by jcw almost 4 years ago

Ah yes, good point - this PCB has a footprint for the CW model!

RE: RFM69 on Raspberry Pi - Added by tht almost 4 years ago

Great catch, thank you. I’ve just ordered some RFM69CW-868MHz modules.

RE: RFM69 on Raspberry Pi - Added by martynj almost 4 years ago

tht,

> Is there any reason NOT to buy the HW model?

Apart from the footprint issue, the 69HW has a slightly less sensitive receiver. Yes, the receiver silicon is identical, but the antenna circuitry is not.
Blasting out those extra db’s from the transmitter section on boost more than compensates for this effect.

From a power consumption standpoint, provided the loop budget is adequate without resorting to Tx > 13dBm nominal output, the 69©W has a slight edge.

    (1-17/17)