Feature request: Support for Xiaomi/Yeelight BLE Candela

travs · May 21, 2022, 5:53am

Any hope of getting support for the Xiaomi/Yeelight Ambiance Candela? It’s a mesh BLE device that works with the Yeelight app. It’s a fairly cool mesh BLE light - would love to get it working w/ MQTT. I found a github repository where someone got it working with Python: GitHub - rytilahti/python-yeelightbt: Python library for Yeelight's bedside (btle) and candela lamps

Thanks!

1technophile · May 21, 2022, 12:55pm

Hello,

You could try first to command it directly with the service / characteristic / value like below:

If you find the good trio you should be able to control the light, we can integrate it after into OMG.

travs · May 22, 2022, 1:11am

That’s a great suggestion. Thank you. I’ll start there.

Follow up - is this the best way to start reverse engineering any BLE device?

1technophile · May 22, 2022, 3:12am

You can take the infos (service/char/value) from existing program like below:

github.com

rytilahti/python-yeelightbt/blob/2736245ebf4205f9e2962faa8c4007749d92064d/yeelightbt/lamp.py#L52

      
        
                            raise
                            _ex = ex
                            try_count -= 1
                            self.connect()
                            continue
                    raise _ex
            
            
    return _wrap
            
            

            
class Lamp:
                REGISTER_NOTIFY_HANDLE = 0x16
                MAIN_UUID =   "8e2f0cbd-1a66-4b53-ace6-b494e25f87bd"
                NOTIFY_UUID = "8f65073d-9f57-4aaa-afea-397d19d5bbeb"
                CONTROL_UUID = "aa7d3f34-2d4f-41e0-807f-52fbf8cf7443"
            
            
    def __init__(self, mac, status_cb=None, paired_cb=None,
                             keep_connection=False, wait_after_call=0):
                    self._mac = mac
                    self._is_on = False
                    self._brightness = None

And see if you succeed controlling

DigiH · May 22, 2022, 1:41pm

Also helpful for the various ON, OFF, INTENSITY, FLICKER command values

github.com

MikeWent/candelabrum/blob/master/candelabrum.py

#!/usr/bin/env python3

import argparse

import pygatt

# get arguments from command line
p = argparse.ArgumentParser()
p.add_argument("--mac", "-m", help="Bluetooth MAC address of Yeelight Candela", type=str, nargs="*", required=True)
g = p.add_mutually_exclusive_group()
g.add_argument("--intensity", "-i", help="Light intensity (0-100)", type=int, required=False)
g.add_argument("--pulse", "-p", help="Enable pulse (flickering) mode", action="store_true", required=False)
args = p.parse_args()

for mac in args.mac:
    # init bluetooth adapter
    print(f"connecting to {mac}")
    try:
        adapter = pygatt.GATTToolBackend()
        adapter.start()

This file has been truncated. show original

github.com

jonofe/candela_socket_server/blob/master/candela_server.py

# ---------------------- config section ---------------------------------

port = 65432					# TCP port to listen on 
mac = "xx:xx:xx:xx:xx:xx" 		# BLE MAC address of your Yelight Candela

# -----------------------------------------------------------------------


import socket
import selectors
import types
import pygatt
import sys
import time
import string
import logging
import binascii

#logging.basicConfig()
#logging.getLogger('pygatt').setLevel(logging.DEBUG)

This file has been truncated. show original

febalci · October 23, 2022, 3:58pm

I am fairly new to BLE and OMG, i started using it just to use it mainly for 2 yeelight candelas. What i achieved so far:

{
  "ble_write_address":"XX:XX:XX:XX:XX:XX",
  "ble_write_service":"0000fe87-0000-1000-8000-00805f9b34fb",
  "ble_write_char":"AA7D3F34-2D4F-41E0-807F-52FBF8CF7443",
  "ble_write_value":"434002",
  "value_type":"HEX",
  "ttl":1,
  "immediate":true }

Change “XX:XX:XX:XX:XX:XX” with your candela BLE address.
“ble_write_value”:“434002” Turns off the candela.
“ble_write_value”:“434001” Turns on the candela.
“ble_write_value”:“4342XX” Adjusts the brightness of the candela between “01-64” hex.

This is for pairing:

{
  "ble_write_address":"XX:XX:XX:XX:XX:XX",
  "ble_write_service":"0000fe87-0000-1000-8000-00805f9b34fb",
  "ble_write_char":"AA7D3F34-2D4F-41E0-807F-52FBF8CF7443",
  "ble_write_value":"4367XXXXXXXXXXXX",
  "value_type":"HEX",
  "ttl":1,
  "immediate":true }

Although i could not confirm if i made the pairing right since i do not know how to read incoming message from BLE devices, either success of failure is not confirmed. I also want to read the status but i do not know how to subscribe to candela NOTIFY_UUID with MQTT, nor could i find any document or sample here.

DigiH · October 24, 2022, 12:24pm

Thanks @febalci for sharing your details for the Yeelight candelas controls.

Pairing and subscribing to NOTIFY is not currently possible through OMG. Only the above WRITE command and the READ command are available, which connect to the device and get/set the service/characteristics available.

0x5e · November 2, 2022, 10:58am

Thanks @febalci for providing the information, my Yeelight BLE Candela is a small different with yours, my service is ‘FE87’.

I’m using hombridge-mqttthing to send mqtt message to OMG:

{
  "accessories": [{
    "accessory": "mqttthing",
    "type": "lightbulb-OnOff",
    "name": "Yeelight烛光氛围灯",
    "manufacturer": "Yeelight",
    "serialNumber": "XXXXXXXXXXXX",
    "model": "yeelight_ms",
    "url": "mqtt://localhost:1883",
    "username": "homebridge",
    "password": "",
    "topics": {
        "setOn": {
            "topic": "home/OpenMQTTGateway_ESP32_BLE/commands/MQTTtoBT/config",
            "apply": "return JSON.stringify({ ble_write_address: 'XX:XX:XX:XX:XX:XX', ble_write_service: 'FE87', ble_write_char: 'AA7D3F34-2D4F-41E0-807F-52FBF8CF7443', ble_write_value: message ? '434001' : '434002', value_type: 'HEX', ttl: 1, immediate: true })"
        },
        "setBrightness": {
            "topic": "home/OpenMQTTGateway_ESP32_BLE/commands/MQTTtoBT/config",
            "apply": "return JSON.stringify({ ble_write_address: 'XX:XX:XX:XX:XX:XX', ble_write_service: 'FE87', ble_write_char: 'AA7D3F34-2D4F-41E0-807F-52FBF8CF7443', ble_write_value: (parseInt('434200', 16) + message).toString(16), value_type: 'HEX', ttl: 1, immediate: true })"
        }
    }
  }]
}

It’s working with about 2 seconds latency, and the problem is, it’s not 100% success. Sometime will failed and OMG & Homebridge doesn’t know it is failed.

I tried change ttl to 5, not sure if it is useful.

And the latency, is there any solution to solve this? Can I make OMG to keep connection with the Yeelight Candela, but not with other sensors? Maybe keep connection can shorten the latency ?

febalci · November 3, 2022, 5:57pm

Hey @0x5e, glad that it worked out, in some way…

Actually mine is called the Yeelight Ambiance, but i think candela and the ambiance s the same product. So, mine also works with FE87 instead of “0000fe87-0000-1000-8000-00805f9b34fb”.

I am sending the mqtt message with MQTTExplorer for test purposes. The latency is not instant but about 1 second. I am not sure if it makes any difference but these devices work as “mac_type”: 0, so you can also add this in your “apply” message. I have no idea what ttl does since i am a total newbie on OMG.

I checked out BLE properties with LightBlue on IOS. The interestğng thing is whenever i connect to yl_candela with LightBlue, the connection drops every 30 secs or so. Then you have to connect it again. I honestly don’t know if all BLE acts this way or it is only candela. It might be because it is not paired; or it might be that candela rests its advertisement every 30 secs.

In fact, the command returns back a success ack:

{"id":"XX:XX:XX:XX:XX",
"service":"0xfe87",
"characteristic":"aa7d3f34-2d4f-41e0-807f-52fbf8cf7443",
"write":"434002",
"success":true}

If the command fails, it returns “false”.

As @DigiH stated in his message, there is no way to subscribe to NOTIFY; it normally provides all status like on/off and brightness value.

0x5e · November 4, 2022, 4:06am

Thanks @febalci , I’m new in OMG too. Where did you get the success ack, from mosquitto_pub? I’m curious why it can receive success ack, I’ve never seen any MQTT client can do this before. I didn’t see the ack from MQTTExplorer too.

To compare with, the Yeelight App can control almost without any latency. And no 30 secs drop issue.

febalci · November 4, 2022, 7:37am

Hey @0x5e, I am using MQTT Explorer; whenever i send a message to candela from “home/OpenMQTTGateway/commands/MQTTtoBT/config”, i check this out “home/OpenMQTTGateway/BTtoMQTT/XXXXXXXXX(candela)”.
Before sending any commands, the yl_candela message there is only RSSI etc. But when you send an on/off or brightness command the message in “home/OpenMQTTGateway/BTtoMQTT/XXXXXXXXX(candela)” changes to the sample i provided in my previous message. So it is technically not an ACK but a response from the candela.

Also, for the latency, if i send the message directly from IOS Lightblue (without MQTT etc, just direct bluetooth transfer command) the latency is close to 0 secs. That means, the route of message from MQTTExplorer to MQTT Server to OpenMQTTGateway to deserialize and send the command to candela, takes more than 1 second as far as i understand.

0x5e · November 4, 2022, 8:08am

Thanks! That really answers my questions which may not clearly written in the docs
I’ve seen the response now, however it will be overwritten after another advertisement…

Edit: my latency and low success rate maybe is the long distance, after moving the device, now it response in about 1 second an almost succeed every time.

And I removed the brightness, at many time, when I modify the brightness, HomeKit will publish a ‘On’ command in addition, which will override the brightness command and decrease the stability.

DigiH · November 4, 2022, 1:28pm

The tip at

Also might not some/all of the service/chars also be READable, to get the status when wanted instead of a notification? Maybe as an additional check to get the status when the immediate response message is not available?

Are you using HomeKit with Homebridge and which Plugin? All up to date?

I also used to have this behaviour, but it was fixed in a recent update.

0x5e · November 4, 2022, 2:34pm

Yeelight BLE Candela’s status seems not available to read or notify, tested on iOS Lightblue, get constant value “0x43ff00000…00000” forever.
I’m using HomeKit with Homebridge and “homebridge-mqttthing” plugin, set command works well in most times, get command not implemented so it only display the status from Homebridge’s accessory cache.

The brightness issue is not a big problem, just because using “homebridge-mqttthing” to read and write has some limitations so it’s not very easy to handle So it’s not the issue for OMG, it’s for plugin I think.

DigiH · November 4, 2022, 4:14pm

Well, it wasn’t that recent, and it was for the homebridge-openhab2-complete Homebridge plugin, which I am using, but this commit addressed and fixed the issue on this plugin side by allowing Homekit to only "sendOnOnlyWhenOff": "true"

with related issues, like

github.com/steilerDev/homebridge-openhab2-complete

Maximum brightness is unreachable depending on OH thing type

opened 10:02AM - 08 Oct 19 UTC

closed 08:16AM - 20 Jul 21 UTC

weakfl

wontfix/delayed

If using dimmers with the OH Zigbee binding (and probably other Zigbee based bin…dings), it is impossible to set a dimmer level of 100. The Zigbee binding will ignore `ON` commands if the dimmer state is already `ON`. This is probably due to the fact, that the binding either restores the last known dimmer level or uses the user defined `On Level` if it receives an `ON` command. In the current implementation, an `ON` command is send instead of `100` when adjusting the brightness level to maximum: https://github.com/steilerDev/homebridge-openhab2-complete/blob/1c24051804c40521b92a22c83a618750c5ecf8f5/accessory/characteristic/SetAndCommitLight.js#L89-L101 I was able to work around this issue by adding an additional state check to the relevant if clauses in lines 90 and 96: ```js if(binary && (brightness === 0 || brightness === 100) && !(service.getCharacteristic(this.Characteristic.On).value)) { // For some reaason when invoking Siri to turn on a light brightness is sometimes set to '0' ``` **However:** I don't know the code well enough to be certain that these changes won't impact other functionality or if there is a better way to solve this issue...

So might be a possible similar solution for the homebridge-mqttthing plugin.

0x5e · November 5, 2022, 4:17am

Wow, thanks for the information!