Shelly RGBW PM Flickering With Home Assistant Transition

Understanding the Flickering Issue with Shelly Plus RGBW PM

When integrating smart home devices, encountering technical glitches can be frustrating. One such issue arises with the Shelly Plus RGBW PM (SNDC-0D4P10WW) when used with Home Assistant. Specifically, users have reported that the light connected to the Shelly device flickers when switched on or off using a transition effect within Home Assistant. This problem doesn't occur when the light is toggled without a transition, indicating a potential conflict between the transition commands issued by Home Assistant and the Shelly device's firmware or hardware. This comprehensive exploration addresses the flickering problems encountered when using a Shelly Plus RGBW PM with Home Assistant, offering insights, troubleshooting techniques, and potential solutions. This article aims to provide a detailed understanding of the issue and guide users toward resolving it effectively.

The core issue is that the Shelly Plus RGBW PM unit appears to have difficulty handling transition commands sent from Home Assistant. Transitions in this context refer to the gradual change in brightness or color when turning a light on or off. Instead of a smooth fade, the light exhibits an undesirable flickering effect. However, it's crucial to note that once the light reaches its target brightness level, the flickering ceases, and the light operates normally. This behavior suggests that the problem is specifically related to the transition process rather than a general instability of the Shelly device or the LED strip itself. Furthermore, users have reported that when controlling the Shelly Plus RGBW PM directly through its native app, transitions work flawlessly, highlighting a discrepancy between how Home Assistant and the Shelly app communicate with the device.

To further isolate the problem, users have conducted several tests within Home Assistant. These tests include: (1) switching the light on or off with a transition, (2) using a scene to switch the light on or off with a transition, and (3) employing a script to control the light with a transition. In all scenarios, the flickering issue persisted, indicating that the problem is not specific to any particular method of controlling the light within Home Assistant. The consistency of this issue across different control methods suggests a fundamental incompatibility between the way Home Assistant implements transitions and how the Shelly device interprets or executes them. It is also important to consider that the issue has been observed across multiple Shelly Plus RGBW PM devices, ruling out the possibility of a hardware defect in a single unit. This widespread occurrence points towards a systemic problem related to either the Shelly firmware, the Home Assistant integration, or a combination of both.

Troubleshooting Steps and Observations

Several troubleshooting steps have been attempted to resolve the flickering issue. First, users have confirmed that the Shelly Plus RGBW PM devices are running the latest firmware version (1.7.1). Keeping the firmware up-to-date is crucial, as firmware updates often include bug fixes and performance improvements that could potentially address compatibility issues. However, in this case, updating to the latest firmware did not resolve the flickering problem, suggesting that the issue lies elsewhere. Additionally, users have verified that the LED strip is powered by a suitable 24V power supply unit with sufficient power. Insufficient power can sometimes cause flickering or other erratic behavior in LED lights, but this has been ruled out as a contributing factor in this scenario. The fact that the light operates normally once it reaches its target brightness further supports the conclusion that the power supply is adequate.

The problem seems to be isolated to the software or communication protocols used by Home Assistant to manage the Shelly device. Analyzing the configuration and communication between Home Assistant and the Shelly device could provide more clues. Reviewing the Home Assistant logs for any error messages or warnings related to the Shelly integration or the light control commands might reveal valuable information. Additionally, examining the device configuration within Home Assistant to ensure that the transition settings are correctly configured could help identify any misconfigurations. The Home Assistant integration relies on specific protocols to communicate with the Shelly device, and any disruption or misinterpretation of these protocols could lead to unexpected behavior. Therefore, a thorough examination of the communication chain between Home Assistant and the Shelly Plus RGBW PM is essential to pinpoint the root cause of the flickering issue.

It is crucial to delve deeper into how Home Assistant handles transitions and how these commands are translated into actions for the Shelly device. Understanding the underlying mechanisms involved in the transition process can shed light on potential areas of conflict. This might involve analyzing the source code of the Home Assistant Shelly integration or using network analysis tools to monitor the communication between Home Assistant and the Shelly device. By dissecting the transition process step by step, it may be possible to identify the specific point at which the flickering is introduced. Furthermore, comparing the transition commands sent by Home Assistant with those used by the Shelly app could reveal differences that explain why the flickering only occurs when using Home Assistant.

Home Assistant Configuration and Environment

The user experiencing the issue is running Home Assistant OS, which is a common and well-supported installation method. This eliminates the possibility of the problem being caused by a specific operating system or installation configuration. The version of Home Assistant Core being used is core-2025.11.1, and the issue persists even when using the latest version. This information is valuable because it rules out the possibility of the problem being a bug that has already been fixed in a more recent version of Home Assistant. The integration causing the issue is the official Shelly integration, which is the standard method for integrating Shelly devices with Home Assistant. This integration is documented on the Home Assistant website, providing a centralized resource for information and troubleshooting tips.

To further assist in diagnosing the problem, the user has provided a diagnostics file (config_entry-shelly-01K8XC5WPBKSBR31YWQB4B4BTG.json). This file contains configuration information about the Shelly device and its integration with Home Assistant. Analyzing this file may reveal specific settings or parameters that could be contributing to the flickering issue. For example, examining the color mode, brightness settings, or transition duration configured in the diagnostics file might provide clues about potential conflicts or misconfigurations. Additionally, the file may contain information about the device's firmware version, IP address, and other relevant details that could be helpful in troubleshooting. Security is a paramount concern in any smart home setup. Ensuring that all devices, including the Shelly Plus RGBW PM, are secured with strong passwords and that the network is protected from unauthorized access is essential. Regularly updating the firmware of all devices is also crucial to patch any security vulnerabilities that may be discovered.

The user has also indicated that there are no relevant error messages or warnings in the Home Assistant logs. This suggests that the problem is not being explicitly reported by Home Assistant, making it more challenging to diagnose. However, it is still possible that there are underlying issues that are not being captured in the logs. In such cases, it may be necessary to enable more verbose logging to capture additional information about the communication between Home Assistant and the Shelly device. This can be done by modifying the Home Assistant configuration file to increase the logging level for the Shelly integration. While increased logging can generate a large amount of data, it may provide valuable insights into the cause of the flickering issue.

Potential Solutions and Workarounds

Given the information available, several potential solutions and workarounds can be explored. One approach is to experiment with different transition settings in Home Assistant. For example, reducing the transition duration or using a different transition type might mitigate the flickering issue. It is possible that the Shelly device is having difficulty handling long or complex transitions, and simplifying the transition settings could improve its performance. Another approach is to investigate alternative methods of controlling the Shelly device within Home Assistant. For example, instead of using the built-in light control features, users could try sending direct commands to the Shelly device using MQTT or other communication protocols. This would bypass the standard Home Assistant integration and allow for more direct control over the device.

Another potential workaround is to use the Shelly app to set up default transition settings for the light. The Shelly app allows users to configure various parameters, including transition durations and brightness levels. By setting these parameters within the Shelly app, the device may be able to handle transitions more smoothly, even when controlled by Home Assistant. This approach would essentially offload the transition processing to the Shelly device itself, potentially reducing the load on Home Assistant and minimizing the risk of flickering. Additionally, users could try using a different type of LED strip with the Shelly Plus RGBW PM. It is possible that the flickering issue is related to the specific characteristics of the LED strip being used, and a different LED strip might be more compatible with the Shelly device.

Furthermore, it is important to report the issue to both the Home Assistant and Shelly development teams. By providing detailed information about the problem, including the steps taken to troubleshoot it, users can help the developers identify and fix the underlying cause. The Home Assistant community forum and the Shelly support website are both good places to report issues and seek assistance from other users and developers. Collaboration between users and developers is essential to ensure that smart home devices and integrations work seamlessly together.

Conclusion

The flickering issue with the Shelly Plus RGBW PM (SNDC-0D4P10WW) when using transitions in Home Assistant appears to stem from a communication or processing conflict between the two systems. While the exact cause remains elusive, the troubleshooting steps and potential solutions outlined above provide a starting point for users to address the problem. By experimenting with different settings, exploring alternative control methods, and reporting the issue to the relevant development teams, users can work towards resolving the flickering and achieving a seamless smart home experience. Remember to ensure your smart home devices' security with strong passwords and regular firmware updates.

For more information on integrating Shelly devices with Home Assistant, visit the official Home Assistant Shelly Integration Documentation.