MQTT Homie: trigger channel silent after reboot

Tags: #<Tag:0x00007f6174a2ce20> #<Tag:0x00007f6174a2cd08>

I’ve set up MQTT 2.4 bindings with Homie and an ESP8266 which has a single button to control some lights. I’ve linked the button to a switch item using the rawbutton-toggle-switch profile (via Paper UI). The first problem I experienced is that a single press triggered multiple events (which makes my lights go crazy):

2019-01-09 19:22:23.580 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered PRESSED
2019-01-09 19:22:23.585 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered PRESSED
2019-01-09 19:22:23.588 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered PRESSED
2019-01-09 19:22:23.592 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered PRESSED
2019-01-09 19:22:23.780 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered RELEASED
2019-01-09 19:22:23.784 [vent.ChannelTriggeredEvent] - mqtt:homie300:f4feb5ec:b361d0:button#button triggered RELEASED

When I subscribe to the channel via Mosquitto I only observe a single message (so ESP and transmission seem to work fine). I thought a restart of OpenHab may help. However, now I don’t see any such messages in the log and the item does not toggle. I can still see the messages in Mosquitto and also the device status is updated in OpenHab

2019-01-09 20:33:14.874 [hingStatusInfoChangedEvent] - 'mqtt:homie300:f4feb5ec:b361d0' changed from ONLINE (CONFIGURATION_PENDING) to ONLINE

QoS is at least once, which might explain the first problem but not the recent problem. Any ideas?

I think a rawbutton produces events as long as it is clicked.

Does it work without the profile?

What firmware do you use?
Is that button debounced?

Does it work without the profile?

As far as I understand a link always has a profile and in case of a button (channel itself is correctly auto-discovered as trigger channel of type system.rawbutton as documented the only profile Paper UI let’s me select is Raw Button Toggle. The docs explicitly mention the switching lights example as a use case for that profile.

What firmware do you use?

I use Homie for ESP8266 (Homie v3 patch). Essentially I follow this:

Is that button debounced?

No, but it’s not the issue as I can confirm by mqtt logs (i pressed the button twice):

$ mosquitto_sub -t '#' -F '@Y-@m-@dT@H:@M:@S@z \e[92m%t \e[96m%p\e[0m' -q 2
2019-01-10T22:01:30+0100 homie/b361d0/button/button PRESSED
2019-01-10T22:01:31+0100 homie/b361d0/button/button RELEASED
2019-01-10T22:01:35+0100 homie/b361d0/button/button PRESSED
2019-01-10T22:01:35+0100 homie/b361d0/button/button RELEASED

Might still be a good idea to add debounce, though.

Removing and recreating the Thing entirely solves the problem. Now, I have exactly one message per button press. But only until the next reboot. A reboot seems to consistently break the setup. Do I need to save something explicitly?

No. There seem to be a bug hidden somewhere. But without knowing your setup it’s hard to replicate.

I think the two issues (no toggle and too many toggles) are related. I can also reproduce the latter. Every time a Homie device goes offline and online again I get an additional log of a press (see above). I suspect that multiple handler run in parallel. And on boot no handler is started.

My setup is OpenHab 2.4.0 on Openhabian (Pi). I’ve created a single switch item and linked the button channel to the item. I’ve noticed in the logs, that on boot all links are recreated (not only mqtt):

2019-01-10 22:59:10.713 [temChannelLinkRemovedEvent] - Link 'Light => mqtt:homie300:f4feb5ec:b361d0:light#on' has been removed.
2019-01-10 22:59:10.716 [temChannelLinkRemovedEvent] - Link 'Light => mqtt:homie300:f4feb5ec:b361d0:button#button' has been removed.
2019-01-10 22:59:10.734 [temChannelLinkRemovedEvent] - Link 'Light => zwave:device:707546a4:node98:switch_binary' has been removed.
2019-01-10 22:59:10.740 [temChannelLinkRemovedEvent] - Link 'Light => mqtt:homie300:66080c3d:button#button' has been removed.
2019-01-10 23:00:37.647 [.ItemChannelLinkAddedEvent] - Link 'Light-mqtt:homie300:f4feb5ec:b361d0:light#on' has been added.
2019-01-10 23:00:37.655 [.ItemChannelLinkAddedEvent] - Link 'Light-zwave:device:707546a4:node98:switch_binary' has been added.
2019-01-10 23:00:37.660 [.ItemChannelLinkAddedEvent] - Link 'Light-mqtt:homie300:f4feb5ec:b361d0:button#button' has been added.
2019-01-10 23:00:37.664 [.ItemChannelLinkAddedEvent] - Link 'Light-mqtt:homie300:66080c3d:button#button' has been added.

Is this on purpose? Is there any other data that might be helpful?

I also tried the embedded mqtt broker. Same behavior.

I’ve also just noticed missing Homie messages after restarting. There is an issue in SmartHome that sounds a lot like the same thing:

I have the exact same error and it has nothing to do with a button. I have a sensor which is constantly sending messages. When i add the thing, it is working. But if i restart openhab the connection is gone.

I figured it out, it is a bug in the mqtt implementation. It is already fixed. In the current Snapshot version it is already working.
A workaround that was working for me: If you delete all retained messages from the broker (e.g. with mqtt explorer), the devices start working again until the next restart.