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XBee serial communication

zigbee
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#1

Hi!

I have a ZigBee network for sensors controlled by an XBee S2C module with ZHA component.
I also have another XBee S2C device that controls a relay. In order to open or close the relay I must send arbitrary bytes to it from the XBee module over UART, i.e. 0x65 to open the relay and 0x6F to close it.
According to the XBee specs (https://www.digi.com/resources/documentation/digidocs/pdfs/90002002.pdf) I must issue an API command (0x10 Transmit Request frame) from the coordinator device (which is controlled by HA).

My problem is that I don’t know how to do it from HA, and even don’t know where start looking.

I guess it is not supported out-of-the-box and I probably need to write a custom module providing the service and probably customize zigpy or zha-quirks or whatever, but I need your advice on where to start, because I am not really familiar with all these stuff yet.

#2

How is the relay connected to the xbee and is the second xbee currently joined to the network?

#3

The relay is connected to the xbee with UART ( http://www.tinyosshop.com/index.php?route=product/product&product_id=595 , http://www.tinyosshop.com/datasheet/TOSR0X-T%20User%20Manual.pdf ).
Yes, it has joined the network already.

#4

Ok, I’m not certain that it’s possible to send arbitrary bytes through the xbee UART in API mode. It may be, but it’s not something I have researched. If it is, you will likely need to build a quirk and probably add the required functionality to zigpy_xbee.

Another option would be to use the DIO pins on the xbee directly, I’m doing that now and am in the process of PRing to zhaquriks https://github.com/dmulcahey/zha-device-handlers/pull/73 This would require you to change relays, I’ve driven 3.3v SSRs directly from the DIO pins without issue.

The other option would be to add a microcontroller and have the device join as a ZHA device. You could then have the microcontroller output the required bytes. This is a project where I am using that method. https://github.com/prairiesnpr/QuadGarageDoorController It’s actually controlling 4 relays, but instead of switching a digital output, you could transmit via the UART.

#5

Thank you!
I can see you are using remote_at_request. I believe I can use tx or tx_explicit to send UART data, without modification of zigpy_xbee.
Besides the quirks, do I need to change anything in HA itself to add a switch or service or sensor based on that quirk?

#6

No, HA will create the appropriate entities based on the endpoints. That quirk looks like this when joined.

SmartSelect_20190513-190931_Edge
SmartSelect_20190513-190931_Edge.jpg1074×1590 336 KB
just edit the replacement endpoint list to match your relay.

#7

Well, I’ve tried that and it works, I can send any data on my coordinator (API mode) and the end device (xbee transparent mode) just prints it to UART. Here is a quick and dirty code that tests the idea, when I flip a switch on or off, it prints ‘d’ or ‘n’: https://github.com/Shulyaka/zha-device-handlers/tree/xbee_dio2

Now, I am thinking on how to do it in a more generic way to be useful for others. Obviously, I don’t want to hardcode TOSR0X commands into xbee zhaquirk because xbee could be connected to a wide range of devices. I think of it as a device that has a service, and any module could call the service with arbitrary data. Any switches or sensors communicating to xbee could be built on top of that service.
This is where I got stuck. I don’t know how to write a zhaquirk that provides a service. Which device type should I use? Are there any other devices out there that require arbitrary data to be sent by HA?