Revive Your ESP32 with Deep Sleep and ESPHome

Table of Contents

1. Introduction
2. Flashing Firmware for ESP Home
   • Connecting Home Assistant with ESP Home
   • Common Configuration Pain Points
3. Best Practice: Using a Secrets File
   • Creating a Secrets File
   • Referencing Key Pairs in Firmware
4. Advanced Configuration: Deep Sleep Mode
   • Benefits and Challenges of Deep Sleep Mode
   • Waking up ESP Devices via MQTT
   • Preventing Deep Sleep Mode with Topic Payload
   • Clearing Retain Flag during Firmware Updates
   • Forcing Deep Sleep Mode as Fallback
5. Conclusion

Flashing Firmware for ESP Home

In this article, we will discuss the process of flashing firmware for ESP Home and its integration with Home Assistant. We will also address some common configuration pain points and provide solutions for a smoother setup. So let's get started!

Connecting Home Assistant with ESP Home

One of the first steps in working with ESP Home is to establish a connection between your iot controller and Home Assistant. This ensures that your devices are properly recognized and can be controlled through the Home Assistant interface. Once the connection is established, you will see a green indicator on the screen, indicating that your iot controller is connected and sending data.

Common Configuration Pain Points

During the initial setup, You may come across some configuration issues that commonly cause frustration. Two of these pain points are mdns and dns name resolution. Mdns is a Broadcast Type of traffic that needs to be allowed through if you are traversing different subnets. Enabling dns name resolution can help resolve connection issues and streamline the setup process. It is recommended to address these configuration points to avoid potential roadblocks later on.

Best Practice: Using a Secrets File

To ensure the security of your firmware and sensitive configuration points, it is best practice to avoid putting passwords directly into the firmware. Instead, we recommend breaking out passwords and other sensitive information into a secrets file. This file will be referenced by the firmware, keeping the sensitive data separate and secure. Let's take a look at how to set up a secrets file.

Creating a Secrets File

To Create a secrets file, navigate to the configuration folder of ESP Home and locate the ESP Home folder within it. Inside this folder, you will find the secrets file. If it does not exist, create the file and open it for editing. In the secrets file, you will insert key pairs for different configurations. For example, you can use the key name "wi-fi" and the corresponding password for your Wi-Fi network. Similarly, you can reference the API password and any other sensitive data in the same way, using Meaningful key names.

Referencing Key Pairs in Firmware

Once you have set up the secrets file with the necessary key pairs, you can reference these keys in your firmware. Instead of using clear text passwords or API keys directly in the firmware code, you will replace them with references to the secrets file. For example, to reference the Wi-Fi password, you would replace it with "secret!wi-fi". The firmware will then retrieve the actual password from the secrets file during runtime, ensuring that sensitive information is not exposed in the firmware code.

Advanced Configuration: Deep Sleep Mode

Now let's explore some advanced configuration options for ESP Home, starting with deep sleep mode. Deep sleep mode is a power-saving feature that allows the device to conserve energy by entering a low-power state when not actively performing tasks. This is particularly useful for battery-powered devices that only need to wake up periodically to send sensor data.

Benefits and Challenges of Deep Sleep Mode

Deep sleep mode offers several benefits, such as extended battery life and reduced power consumption. However, it also presents challenges when it comes to firmware updates or making code modifications. In deep sleep mode, the device wakes up for a brief period to send sensor data and quickly goes back to sleep, making it difficult to catch during this short wake-up period. To address this challenge, ESP Home provides a solution using MQTT.

Waking up ESP Devices via MQTT

With MQTT, you can wake up ESP devices from deep sleep mode by sending a specific message to their designated MQTT topic. When an ESP device wakes up, it connects to the MQTT broker and checks for a predefined payload in a specified topic. If it receives the designated payload, it prevents the device from going back to deep sleep mode and allows you to flash new firmware or make necessary code modifications.

Preventing Deep Sleep Mode with Topic Payload

To prevent an ESP device from entering deep sleep mode, you need to send an "on" payload to the designated MQTT topic. This payload, which is case-sensitive, signals to the device that it should remain active instead of going back to sleep. It is important to set the retain flag for this message to ensure it is retained by the MQTT broker. This way, the message remains available for the device to check even if it wakes up after a long period.

Clearing Retain Flag during Firmware Updates

During firmware updates, it is crucial to clear the retain flag for the payload message before the device reboots. This ensures that the device does not keep receiving the same message repeatedly. To clear the retain flag, you can send an empty payload with the retain flag set to null (dash r dash n). This action tells the device that it should not receive any specific payload and can go back to deep sleep mode after reboot.

Forcing Deep Sleep Mode as Fallback

As a fallback method, you can also force an ESP device into deep sleep mode by sending an "on" payload to the designated MQTT topic. This can be useful if you forget to disable the retain flag before rebooting the device. By sending the "on" payload, you instruct the device to immediately enter deep sleep mode, providing a fail-safe option to ensure the device is not caught in a loop.

Conclusion

In this article, we have covered the process of flashing firmware for ESP Home and explored advanced configuration options such as deep sleep mode. Implementing best practices like using a secrets file to store sensitive information helps enhance the security of your devices. Additionally, understanding the use of MQTT for waking up ESP devices from deep sleep mode can simplify firmware updates and code modifications. We hope this article has provided valuable insights and guidance for working with ESP Home.