I had a look at the Home Assistant logs and I think I have been blaming the wrong beast, my code seems to be innocent.

I use appdaemon to execute actions in/from Home Assistant. There I can see exactly when a "ghost"-update was received.

Matching those timestamps with timestamps from the Home Assistant log was spot on:

Appdaemon log:

2020-03-11 09:38:23.092076 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 09:39:48.834817 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 09:48:03.398937 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 09:49:19.742706 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:05:24.735442 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:06:58.973448 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:38:26.141511 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:39:42.890820 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:47:59.874830 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 10:49:16.437996 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 11:15:23.592502 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 11:16:40.138025 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 11:18:05.195990 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 11:19:39.443632 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:27:05.469657 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:28:22.691106 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:35:15.985303 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:36:33.073911 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:40:29.881660 INFO Living_Room_IR: ir_value: 551505585
2020-03-11 12:42:01.804079 INFO Living_Room_IR: ir_value: 551505585

Here is the corresponding part of the home assistant log:

{"log":"2020-03-11 09:38:22 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T08:38:22.931537407Z"}
{"log":"2020-03-11 09:39:48 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T08:39:48.650792534Z"}
{"log":"2020-03-11 09:48:03 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T08:48:03.210220912Z"}
{"log":"2020-03-11 09:49:19 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T08:49:19.579932619Z"}
{"log":"2020-03-11 10:05:24 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:05:24.564205929Z"}
{"log":"2020-03-11 10:06:58 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:06:58.804235809Z"}
{"log":"2020-03-11 10:38:25 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:38:25.95710773Z"}
{"log":"2020-03-11 10:39:42 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:39:42.703318764Z"}
{"log":"2020-03-11 10:47:59 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:47:59.694853604Z"}
{"log":"2020-03-11 10:49:16 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T09:49:16.294815751Z"}
{"log":"2020-03-11 11:15:23 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T10:15:23.452517606Z"}
{"log":"2020-03-11 11:16:39 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T10:16:39.957885612Z"}
{"log":"2020-03-11 11:18:05 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T10:18:05.045447402Z"}
{"log":"2020-03-11 11:19:39 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T10:19:39.270413469Z"}
{"log":"2020-03-11 12:27:05 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:27:05.326243334Z"}
{"log":"2020-03-11 12:28:22 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:28:22.519338238Z"}
{"log":"2020-03-11 12:35:15 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:35:15.805191381Z"}
{"log":"2020-03-11 12:36:32 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:36:32.903939567Z"}
{"log":"2020-03-11 12:40:29 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:40:29.720752968Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:42:01.635196016Z"}

So it seems that every time a Node update was triggered Home Assistant was told that there was a new value received from the IR-sensor.

Here is the whole log from Home Assistant:

{"log":"2020-03-11 12:42:00 DEBUG (MainThread) [mysensors.handler] n:0 c:255 t:3 s:9 p:11494641 TSF:MSG:RE
AD,3-3-0,s=0,c=1,t=1,pt=7,l=5,sg=0:38.4\n","stream":"stderr","time":"2020-03-11T11:42:00.295978262Z"}
{"log":"2020-03-11 12:42:00 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 0\n","stream":"stderr","time":"2020-03-11T11:42:00.311538101Z"}
{"log":"2020-03-11 12:42:00 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 0: value_type 1, value = 38.4\n","stream":"stderr","time":"2020-03-11T11:42:00
.415847867Z"}
{"log":"2020-03-11 12:42:00 DEBUG (MainThread) [mysensors.handler] n:0 c:255 t:3 s:9 p:11495280 TSF:MSG:RE
AD,3-3-0,s=2,c=1,t=37,pt=7,l=5,sg=0:45.0\n","stream":"stderr","time":"2020-03-11T11:42:00.93325235Z"}
{"log":"2020-03-11 12:42:00 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 2\n","stream":"stderr","time":"2020-03-11T11:42:00.950559479Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 2: value_type 37, value = 45.0\n","stream":"stderr","time":"2020-03-11T11:42:0
1.058505324Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [mysensors.handler] n:0 c:255 t:3 s:9 p:11495962 TSF:MSG:RE
AD,3-3-0,s=255,c=3,t=0,pt=1,l=1,sg=0:22\n","stream":"stderr","time":"2020-03-11T11:42:01.618936799Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.gateway] Node update: n
ode 3 child 255\n","stream":"stderr","time":"2020-03-11T11:42:01.635196016Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 0: value_type 1, value = 38.4\n","stream":"stderr","time":"2020-03-11T11:42:01
.738527926Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 1: value_type 0, value = 22.4\n","stream":"stderr","time":"2020-03-11T11:42:01
.743098362Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 3: value_type 50, value = 624502100\n","stream":"stderr","time":"2020-03-11T11
:42:01.747319859Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 3: value_type 33, value = 551505585\n","stream":"stderr","time":"2020-03-11T11
:42:01.748432047Z"}
{"log":"2020-03-11 12:42:01 DEBUG (MainThread) [homeassistant.components.mysensors.device] Entity update:
mysensors_wohnzimmer_main 3 2: value_type 37, value = 45.0\n","stream":"stderr","time":"2020-03-11T11:42:0
1.752559045Z"}
{"log":"2020-03-11 12:42:02 DEBUG (SyncWorker_3) [mysensors.persistence] Saving sensors to persistence fil
e /config/mysensorsserial.json\n","stream":"stderr","time":"2020-03-11T11:42:02.441267303Z"}

Does anybody have an idea how I can prevent these updates? Or should I continue this thread in the Home Assistant forum of mysensors?

Seems you where both right. A short drained the battery (which I didn't notice) and getting rid of the short and using a new set of rechargeables solved the problem.

Thank you very much!

@KevinT

Thank you for your feedback!

I have (or at least I think) a decoupling cap on the pcb (C2). And you are right, I should have added the schematics from the start.

I tried doing it on openhardware.io but now the pics of the pcb itself show an older version (the schematics are fine though, I'll add them here too).

I added pins for a HDC1080 temperature/humidity sensor, because that's what I'll probably end up adding anway.

1 interrupt should be all that I need, but if I need more I'll probably use this workaround. But thank you for letting me know about the micro, didn't even know that existed :)

@skywatch That's pretty sad to hear.... it's what got me into electronics/soldering. Are there any comparable projects that are seeing development?

@mfalkvidd

I am a bit embarrassed that I didn't post them straight away. I'll collect a bit of data during the night and send the logs tomorrow. Thanks!

@mfalkvidd

Good catch, I didn't do that. Before I saw your message I checked the wiring and I introduced a new bug apparently because now the MQTT-gateway doesn't start anymore either, so I'll have to rewire.

I'll write again after I did that. Thanks for the help!

@sundberg84 I did, thanks, I discovered ISRs. Thanks for the support.

@mfalkvidd

I am planning on using a booster, so that's very good to know, thanks!

@mfalkvidd @phildefer

I can confirm that the code compiles and runs on my rasbperry pi 4 model b. I am using a rfm69 radio and that seems to be working too. I couldn't test it yet though since I haven't wired any rfm69 nodes up yet.

So this was either a faulty module or bad soldering. I soldered a new module and now everything works as expected. Thanks for the help!

@electrik perfect, thank you both!

I think this was solved by soldering a wire to the reset pin of the rfm69 and pin 29 of the raspberry pi and reconfiguring the gateway with

--extra-cxxflags="-DMY_RFM69_RST_PIN=29"

Now the connection is instant (before it was about 10-20 seconds IF it worked at all.

But since this is my first gig with electronics it might just be that I had a bad connection and moving the wires around fixed it....

@ricmail85 sorry for the late reply. I soldered it to a free pin on the pi and reconfigured the gateway.

Use this as part of your configure

--extra-cxxflags="-DMY_RFM69_RST_PIN=29"

If you connected to pi pin 29.

@mfalkvidd

Oh, I completely misunderstood then! I thought mysgw would interpret the serial input and then make it accessible to the controller.

Thanks för clearing that up, I will give it a shot tomorrow.