TRMNL

The TRMNL integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] allows you to monitor your TRMNL e-paper (e-ink) displays in Home Assistant. TRMNL devices are low-power e-ink displays that show content such as calendars, weather, and custom dashboards at a glance.

With this integration, you can track the battery level of your TRMNL devices and automate your home around them. For example, you could get a notification when the battery is running low, or align the sleep schedule of your display with your own.

Supported devices

The following TRMNL hardware devices are supported:

• TRMNL (OG)
• TRMNL (X)

Prerequisites

To use this integration, you need a TRMNL developer license.

1. Open your TRMNL account settings.
2. Copy your API key. It starts with user_.

Configuration

To add the TRMNL hub to your Home Assistant instance, use this My button:

Supported functionality

The TRMNL integration provides the following entities for each TRMNL device on your account.

Sensors

• Battery: The current battery level of the device, in percent.
• Battery voltage: The current battery voltage of the device, in volts (V). This entity is disabled by default.
• Signal strength: The raw Wi-Fi received signal strength indicator (RSSI) of the device, in dBm. This entity is disabled by default.
• Wi-Fi strength: The Wi-Fi connection quality of the device, shown as a percentage derived from the RSSI value. This entity is disabled by default.

Switches

• Sleep mode: Enables or disables the sleep schedule on the device. When enabled, the device will sleep between the Sleep start time and Sleep end time.

Time

• Sleep start time: The time at which the device enters sleep mode.
• Sleep end time: The time at which the device wakes up from sleep mode.

Examples

Send a notification when the battery is low

This automation sends a notification to your phone when the battery level of your TRMNL device drops below 20%.

alias: "Notify when TRMNL battery is low"
description: >
  Send a notification when the TRMNL battery level
  drops below 20%.
triggers:
  - trigger: numeric_state
    entity_id: sensor.your_trmnl_battery
    below: 20
actions:
  - action: notify.mobile_app_your_phone
    data:
      title: "TRMNL battery low"
      message: "Your TRMNL battery is below 20%. Time to charge it."

Data updates

The integration pollsData polling is the process of querying a device or service at regular intervals to check for updates or retrieve data. By defining a custom polling interval, you can control how frequently your system checks for new data, which can help optimize performance and reduce unnecessary network traffic. [Learn more] the TRMNL API every hour to update the device and entity states, including sensor readings and the Sleep mode switch.

Known limitations

• The integration does not support sending custom content to the display. It only allows you to monitor the device status and control the sleep schedule.

Troubleshooting

Setup fails with an authentication error

Symptom: “Invalid authentication”

When adding the integration, the setup fails with an authentication error.

Description

This most commonly happens when the wrong API key is used. The integration requires your account API key (which starts with user_), not the device-level token that is shown in the individual device settings.

Resolution

1. Open your TRMNL account settings.
2. Copy the API key shown there. Make sure it starts with user_.
3. Re-enter this key in the integration setup.

Removing the integration

This integration follows standard integration removal. No extra steps are required.

To remove an integration instance from Home Assistant

1. Go to Settings > Devices & services and select the integration card.
2. From the list of devices, select the integration instance you want to remove.
3. Next to the entry, select the three dots menu. Then, select Delete.