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pymysensors Build Status

Python API for talking to a MySensors gateway. Currently supports serial protocol v1.4, v1.5, v2.0 - v2.2. Not all features of v2.x are implemented yet.

  • Supports smartsleep with serial API v2.x.
  • Supports the MQTT client gateway with serial API v2.x.
  • Supports OTA updates, for both DualOptiboot and MYSBootloader bootloaders.
  • All gateway instances, serial, tcp (ethernet) or mqtt will run in separate threads.
  • As an alternative to running the gateway in its own thread, there are experimental implementations of all gateways using asyncio.


pymysensors requires Python 3.7+.


You can easily install it from PyPI:

pip3 install pymysensors


Currently the API is best used by implementing a callback handler

import mysensors.mysensors as mysensors

def event(message):
    """Callback for mysensors updates."""
    print('sensor_update ' + str(message.node_id))

GATEWAY = mysensors.SerialGateway('/dev/ttyACM0', event)

In the above example pymysensors will call "event" whenever a node in the Mysensors network has been updated. The message passed to the callback handler has the following data:

    gateway - the gateway instance
    node_id - the sensor node identifier
    child_id - the child sensor id
    type - the message type, for example "set" or "presentation" (int)
    ack - True is message was an ACK, false otherwise (0 or 1)
    sub_type - the message sub_type (int)
    payload - the payload of the message (string)

Note: The content of the sub_type differs according to the context. In presentation messages, the sub_type denotes S_TYPE data (such as S_INFO). In 'set' and 'req' messages the sub_type denotes V_TYPE data (such as V_TEXT).

Symbolic names for the Message types and sub_types are defined in the protocol version-specific files.

The data structure of a gateway and it's network is described below.

    sensors - a dict containing all nodes for the gateway; node is of type Sensor

Sensor - a sensor node
    children - a dict containing all child sensors for the node
    sensor_id - node id on the MySensors network
    type - 17 for node or 18 for repeater
    protocol_version - the mysensors protocol version used by the node

ChildSensor - a child sensor
    id - child id on the parent node
    type - data type, S_HUM, S_TEMP etc.
    description - the child description sent when presenting the child
    values - a dictionary of values (V_HUM, V_TEMP, etc.)

Getting the type and values of node 23, child sensor 4 would be performed as follows:

s_type = GATEWAY.sensors[23].children[4].type
values = GATEWAY.sensors[23].children[4].values

Similarly, printing all the sketch names of the found nodes could look like this:

for node in GATEWAY.sensors.values():

Getting a child object inside the event function could be:

    if GATEWAY.is_sensor(message.node_id, message.child_id):
        child = GATEWAY.sensors[message.node_id].children[message.child_id]
        print("Child not available yet.")

To update a node child sensor value and send it to the node, use the set_child_value method in the Gateway class:

# To set sensor 1 (int), child 1 (int), sub-type V_LIGHT (= 2) (int), with value 1.
GATEWAY.set_child_value(1, 1, 2, 1)


With persistence mode on, you can restart the gateway without having to restart each individual node in your sensor network. To enable persistence mode, the keyword argument persistence in the constructor should be True. A path to the config file can be specified as the keyword argument persistence_file. The file type (.pickle or .json) will set which persistence protocol to use, pickle or json. JSON files can be read using a normal text editor. Saving to the persistence file will be done on a schedule every 10 seconds if an update has been done since the last save. Make sure you start the persistence saving before starting the gateway.


Protocol version

Set the keyword argument protocol_version to set which version of the MySensors serial API to use. The default value is '1.4'. Set the protocol_version to the version you're using.

Serial gateway

The serial gateway also supports setting the baud rate, read timeout and reconnect timeout.

import mysensors.mysensors as mysensors

def event(message):
    """Callback for mysensors updates."""
    print("sensor_update " + str(message.node_id))

GATEWAY = mysensors.SerialGateway(
  '/dev/ttyACM0', baud=115200, timeout=1.0, reconnect_timeout=10.0,
  event_callback=event, persistence=True,
  persistence_file='some_folder/mysensors.pickle', protocol_version='2.2')
GATEWAY.start_persistence() # optional, remove this line if you don't need persistence.

There are two other gateway types supported besides the serial gateway: the tcp-ethernet gateway and the MQTT gateway.

TCP ethernet gateway

The ethernet gateway is initialized similar to the serial gateway. The ethernet gateway supports setting the tcp host port, receive timeout and reconnect timeout, besides the common settings and the host ip address.

GATEWAY = mysensors.TCPGateway(
  '', port=5003, timeout=1.0, reconnect_timeout=10.0,
  event_callback=event, persistence=True,
  persistence_file='some_folder/mysensors.pickle', protocol_version='1.4')

MQTT gateway

The MQTT gateway requires MySensors serial API v2.0 or greater and the MQTT client gateway example sketch loaded in the gateway device. The gateway also requires an MQTT broker and a python MQTT client interface to the broker. See for an example of how to implement this and initialize the MQTT gateway.

Over the air (OTA) firmware updates

Call Gateway method update_fw to set one or more nodes for OTA firmware update. The method takes three positional arguments and one keyword argument. The first argument should be the node id of the node to update. This can also be a list of many node ids. The next two arguments should be integers representing the firmware type and version. The keyword argument is optional and should be a path to a hex file with the new firmware.

GATEWAY.update_fw([1, 2], 1, 2, fw_path='/path/to/firmware.hex')

After the update_fw method has been called the node(s) will be requested to restart when pymysensors Gateway receives the next set message. After restart and during the MySensors begin method, the node will send a firmware config request. The pymysensors library will respond to the config request. If the node receives a proper firmware config response it will send a firmware request for a block of firmware. The pymysensors library will handle this and send a firmware response message. The latter request-response conversation will continue until all blocks of firmware are sent. If the CRC of the transmitted firmware match the CRC of the firmware config response, the node will restart and load the new firmware.

Gateway id

The gateway method get_gateway_id will try to return a unique id for the gateway. This will be the serial number of the usb device for serial gateways, the mac address of the connected gateway for tcp gateways or the publish topic prefix (in_prefix) for mqtt gateways.

Connection callbacks

It's possible to register two optional callbacks on the gateway that are called when the connection is made and when the connection is lost to the gateway device. Both callbacks should accept a gateway parameter, which is the gateway instance. The connection lost callback should also accept a second parameter for possible connection error exception argument. If connection was lost without error, eg when disconnecting, the error argument will be None.

NOTE: The MQTT gateway doesn't support these callbacks since the connection to the MQTT broker is handled outside of pymysensors.

def conn_made(gateway):
  """React when the connection is made to the gateway device."""

GATEWAY.on_conn_made = conn_made

def conn_lost(gateway, error):
  """React when the connection is lost to the gateway device."""

GATEWAY.on_conn_lost = conn_lost

Async gateway

The serial, TCP and MQTT gateways now also have versions that support asyncio. Use the AsyncSerialGateway class, AsyncTCPGateway class or AsyncMQTTGateway class to make a gateway that uses asyncio. The following public methods are coroutines in the async gateway:

  • get_gateway_id
  • start_persistence
  • start
  • stop
  • update_fw

See for an example of how to use this gateway.


Install the packages needed for development.

pip install -r requirements_dev.txt

Use the Makefile to run common development tasks.


Code formatting

We use black code formatter to automatically format the code.

black ./


See the release instructions.