The MySensors project combines devices like Arduino, ESP8266, Raspberry Pi, NRF24L01+ and RFM69 to build affordable sensor networks. This integration will automatically add all available devices to Home Assistant, after presentation is done. That is, you do not need to add anything to your configuration for the devices for them to be added. Go to the states section of the developer tools to find the devices that have been identified.


Integrate your Serial, Ethernet (LAN) or MQTT MySensors Gateway by adding the following to your configuration.yaml file:

# Example configuration.yaml entry
    - device: '/dev/ttyUSB0'

Configuration Variables

gateways map Required

A list of gateways to set up.

device string Required

The path to the serial gateway where it is connected to your Home Assistant host, or the address of the TCP Ethernet gateway, or mqtt to setup the MQTT gateway. Resolving DNS addresses is theoretically supported but not tested.

baud_rate integer (Optional, default: 115200)

Specifies the baud rate of the connected serial gateway.

persistence_file string (Optional)

The path to a file to save sensor information. The file extension determines the file type. Currently supported file types are ‘pickle’ and ‘json’.



tcp_port integer (Optional, default: 5003)

Specifies the port of the connected TCP Ethernet gateway.

topic_in_prefix string (Optional)

Set the prefix of the MQTT topic for messages coming from the MySensors gateway in to Home Assistant.

topic_out_prefix string (Optional)

Set the prefix of the MQTT topic for messages going from Home Assistant out to the MySensors gateway.

nodes map (Optional)

A mapping of node ids to node settings, e.g., custom name.

name string Required

The name the node will be renamed to. This node name becomes part of the entity_id. Default entity_id is [sketch_name]_[node_id]_[child_id] and when this name is set, the entity_id becomes [name]_[child_id].

persistence integer (Optional, default: true)

Enable or disable local persistence of sensor information. If this is disabled, then each sensor will need to send presentation messages after Home Assistant starts.

version string (Optional, default: 1.4)

Specifies the MySensors protocol version to use. Supports versions 1.4 to 2.3.

optimistic integer (Optional, default: false)

Enable or disable optimistic mode for actuators (switch/light). Set this to true if no state feedback from actuators is possible. Home Assistant will assume that the command succeeded and change state.

retain integer (Optional, default: true)

Enable or disable retain flag for published messages from Home Assistant when using the MQTT gateway.

Not all features of MySensors 2.x are supported by Home Assistant yet. As more features are added, they will be described here in the documentation. Go to the MySensors platform pages under "related components" to see what message types are currently supported.

If you are using an original Arduino as a serial gateway, the port will be named ttyACM*. The exact number can be determined with the command shown below.

ls /dev/ttyACM*

If you are using the MQTT gateway, you also need to have the MQTT component configured in Home Assistant. See below for a minimum MQTT configuration:

  client_id: home-assistant-1
The MQTT gateway requires MySensors version 2.0+ and only the MQTT client gateway is supported.

Extended configuration example

# Example configuration.yaml entry
    - device: '/dev/ttyUSB0'
      persistence_file: 'path/mysensors.json'
      baud_rate: 38400
          name: 'kitchen'
          name: 'living_room'
    - device: '/dev/ttyACM0'
      persistence_file: 'path/mysensors2.json'
      baud_rate: 115200
    - device: ''
      persistence_file: 'path/mysensors3.json'
      tcp_port: 5003
    - device: mqtt
      persistence_file: 'path/mysensors4.json'
      topic_in_prefix: 'mygateway1-out'
      topic_out_prefix: 'mygateway1-in'
  optimistic: false
  persistence: true
  retain: true
  version: '2.0'


Present a MySensors sensor or actuator, by following these steps:

  1. Connect the serial gateway to your computer or the Ethernet or MQTT gateway to your network.
  2. Configure the MySensors integration in configuration.yaml.
  3. Start Home Assistant.
  4. Write and upload your MySensors sketch to the sensor. Make sure you:
    • Send sketch name.
    • Present the sensor’s S_TYPE.
    • Send at least one initial value per V_TYPE. In version 2.x of MySensors, this has to be done in the loop function. See below for an example in 2.0 of how to make sure the initial value has been received by the controller.
  5. Start the sensor.
 * Documentation:
 * Support Forum:

#define MY_DEBUG
#define MY_RADIO_NRF24
#define MY_NODE_ID 1
#include <SPI.h>
#include <MySensors.h>
#include <Bounce2.h>

#define RELAY_PIN  5
#define BUTTON_PIN  3
#define CHILD_ID 1
#define RELAY_ON 1
#define RELAY_OFF 0

Bounce debouncer = Bounce();
bool state = false;
bool initialValueSent = false;

MyMessage msg(CHILD_ID, V_STATUS);

void setup()

  // Make sure relays are off when starting up
  digitalWrite(RELAY_PIN, RELAY_OFF);

void presentation()  {
  sendSketchInfo("Relay+button", "1.0");
  present(CHILD_ID, S_BINARY);

void loop()
  if (!initialValueSent) {
    Serial.println("Sending initial value");
    Serial.println("Requesting initial value from controller");
    request(CHILD_ID, V_STATUS);
    wait(2000, C_SET, V_STATUS);
  if (debouncer.update()) {
    if ( {
      state = !state;
      // Send new state and request ack back
      send(msg.set(state?RELAY_ON:RELAY_OFF), true);

void receive(const MyMessage &message) {
  if (message.isAck()) {
     Serial.println("This is an ack from gateway");

  if (message.type == V_STATUS) {
    if (!initialValueSent) {
      Serial.println("Receiving initial value from controller");
      initialValueSent = true;
    // Change relay state
    state = (bool)message.getInt();
    digitalWrite(RELAY_PIN, state?RELAY_ON:RELAY_OFF);


Sending a heartbeat, I_HEARTBEAT_RESPONSE, from the MySensors device to Home Assistant, using MySensors version 2.0 - 2.1, activates the SmartSleep functionality in Home Assistant. This means that messages are buffered and only sent to the device upon receiving a heartbeat from the device. State changes are stored so that only the last requested state change is sent to the device. Other types of messages are queued in a FIFO queue. SmartSleep is useful for battery powered actuators that are waiting for commands. See the MySensors library API for information on how to send heartbeats and sleep the device.

In MySensors version 2.2 the serial API changed from using I_HEARTBEAT_RESPONSE to signal SmartSleep, to using I_PRE_SLEEP_NOTIFICATION and I_POST_SLEEP_NOTIFICATION. Home Assistant has been upgraded to support the new message types and will activate SmartSleep when receiving a message of type I_PRE_SLEEP_NOTIFICATION, if using MySensors version 2.2.x or higher. If Home Assistant is configured to use MySensors version 2.0 - 2.1 the old SmartSleep behavior is retained.

Message validation

Messages sent to or from Home Assistant from or to a MySensors device will be validated according to the MySensors serial API. If a message doesn’t pass validation, it will be dropped and not be passed forward either to or from Home Assistant. Make sure you follow the serial API for your version of MySensors when writing your Arduino sketch.

The log should warn you of messages that failed validation or if a child value is missing that is required for a certain child type. Home Assistant will log failed validations of child values at warning level if e.g., one required value type for a platform has been received, but other required value types are missing.

Message validation was introduced in version 0.52 of Home Assistant.

Debug logging

If you experience dropped messages or that a device is not added to Home Assistant, please turn on debug logging for the mysensors integration and the mysensors package. This will help you see what is going on. Make sure you use these logging settings to collect a log sample if you report an issue about the mysensors integration in our GitHub issue tracker.

  default: info
    homeassistant.components.mysensors: debug
    mysensors: debug

Visit the library API of MySensors for more information.