Rtl_433 - how to get output to HA

Configuration
1

Hi All,
Did the hard bit - now can’t do the easy bit !

I got a energy monior (current cost) and I got a cheap SDR stick for my pi. Installed a load of stuff and after some pain installing the libraries and usb hub for power I can do this…

pi@custard-pi:~ $ sudo rtl_433 -q -R 43
Found Rafael Micro R820T tuner
Exact sample rate is: 250000.000414 Hz
Sample rate set to 250000.
Bit detection level set to 0 (Auto).
Tuner gain set to Auto.
Tuned to 433920000 Hz.
2016-10-31 16:13:31 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         444 W
        Power 2:         0 W
2016-10-31 16:13:37 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         446 W
        Power 2:         0 W

So I thought - happy days - all i need to do now is redirect output to a file and have HA read it.

I ca’t do that bit !

I was planning to grep / awk the output down to the wattage number (most recent) so in this case 446. and then overwrite a file continually with that number.

I thought just…

sudo rtl_433 -q -R 43 > /path/to/datafile

but that appends I thought > should overwrite. “>>” is append. Anyone help me with the secret sauce?

2

anyone able to help, probably more of a linux / bash question but if I get this working I can then get it hooked up to HA via a command line sensor I guess.

3

I have appdeamon installed and with that it would be simple to split out the file to anything you like and then use it in HA.
without that i have to little knowledge from Linux to be able to do such a thing.

4

Not sure I understand.

All I want to do is have the rtl_433 ouput the current power usage to a file (and overwrite). I’d then handle the reading of that file.

5

Did you try:

yourcommand > yourfile 2>&1

6

yes - thanks - that was my first instinct. It works but unfortunately the file keeps growing, the latest reading is appended to the bottom of the file.

7

How about:

sudo bash -c 'yourcommand > yourfile'

And do you have to sudo this? Better to give yourself permissions I think. Don’t know if that’s the culprit, but I expect it might be.

8

that’s right - I get “two”, just did it. No strange aliases AFAIK…

I guess the problem is that the application rtl_433 is continually churning out this log of values and the whole thing is getting added to my file rather than just the latest… bit frustrating

9

Just edited my last post, sorry about that.

10

sorry, i understood wrong.
i thought you knew how to make the file and didnt know how to get it to HA :wink:

what kind of application is this rtl_433?

11

ahhh, no - I’m at the first stage, getting the data onto the pi in a sensible form.

Here’s the app…

basically it reads a USB SDR stick and which is monitoring an electricity reader (current cost). I thought I’d done the tricky bit when I got the readings on my screen…

12

How about:

sudo bash -c 'yourcommand > yourfile'

And do you have to sudo this? Better to give yourself permissions I think. Don’t know if that’s the culprit, but I expect it might be.

13

yes tried that - got the same result - appended data to the file ( new reading every six seconds or so.

need sudo to run the command I think the privilege is required to get the readings, I don’t think that’s the problem though - maybe just the way the app writes out the data in a rolling fashion?

14

oh – so the program continues running. Well, this is the expected behavior then – it keeps stdout open, and you are redirecting it to a file, which is being appended to because the stream is still open.

You could:

  1. do what you’re doing now, writing to file A (or as @ReneTode just mentioned, instead of redirecting using >, look at the usage for rtl_433 which says you can just specify a filename, either way, same result)
  2. write another script which will loop forever, open file A, look for the last occurrence of your search string, append THAT to another file, file B, (which will be overwritten each time), delay, recur the loop
15

how about using

rtl_433 filename

instead off trying to save your screenoutput?

16

ok, I hear you - thanks for this - at least I’m not going nuts. I get it - It’s doing what it should, just not what I need.

Yes, i played with the output options of rtl_433 to try and find a way but no luck. Just specifying a filename actually seems to decode the radio singals on the fly - recording if you like - you end up with megabytes of undecoded radio signal data in a few seconds!

17

which options do give you this output?

18 
pi@custard-pi:~ $ sudo rtl_433 -q -R 43
Found Rafael Micro R820T tuner
Exact sample rate is: 250000.000414 Hz
Sample rate set to 250000.
Bit detection level set to 0 (Auto).
Tuner gain set to Auto.
Tuned to 433920000 Hz.
2016-10-31 16:13:31 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         444 W
        Power 2:         0 W
2016-10-31 16:13:37 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         446 W
        Power 2:         0 W

in the file I redirect to I just get…

2016-10-31 16:13:31 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         444 W
        Power 2:         0 W
2016-10-31 16:13:37 :   CurrentCost TX
        Device Id:       3709
        Power 0:         0 W
        Power 1:         446 W
        Power 2:         0 W

....... and on and on....
19

and when you use:

sudo rtl_433 -q -W -R 43

20

just tried with the -W option, appends to file as well unfortunately. I agree - it looked promising.