ESPurna

ESPurna ("spark" in Catalan) is a custom C firmware for ESP8266 based smart switches. It was originally developed with the ITead Sonoff in mind. This device has an ESP8266 on board with a 8Mbit flash memory chip, a mains to 3V3 transformer and a relay (GPIO12). It also features a button (GPIO0), an LED (GPIO13) and an unpopulated header you can use to reprogram it. You can read about this board and firmware in my blog.

Hardware support

Features

WebServer for configuration and simple relay toggle
Flashing firmware Over-The-Air (OTA)
Up to 3 configurable WIFI networks
MQTT support with configurable host and topic
Manual switch ON/OFF with button (single click the button)
AP mode backup (double click the button)
Visual status of the connection via the LED
Support for custom RF module
Support for automatic over-the-air updates through the NoFUSS Library
Support for current monitoring through then EmonLiteESP Library
Support for DHT22 sensors
Command line configuration

Flashing a Sonoff

This section only applies to the Sonoff, but pretty much every other ESP8266-based hardware will be similar.

The unpopulated header in the Sonoff has all the required pins. My board has a 5 pins header in-line with the button. They are (from the button outwards):

3V3
RX
TX
GND
GPIO14

Last one is not necessary. Mind it's a 3V3 device, if connected to 5V you will probably fry it. Button is connected to GPIO0 on the ESP8266 chip, so to enter flash mode you have to hold the button pressed while powering on the board, then you can realease it again.

Firmware

The project is ready to be build using PlatformIO. Please refer to their web page for instructions on how to install the builder.

PlatformIO will take care of some of the library dependencies, but not all the required libraries are available in the platform library manager. Some dependencies are thus checked out as submodules in GIT. So the normal initial checkout should be:

git clone git@bitbucket.org:xoseperez/espurna.git
git submodule init
git submodule update

On linux/max systems the libraries are soft linked to the code/lib folder and you are ready to go. Windows systems do not have this feature so you will have to copy them manually like this (ONLY WINDOWS):

cd espurna/code
copy vendor/embedis/src lib/Embedis
copy vendor/emonliteesp/code/lib/EmonLiteESP lib/EmonLiteESP
copy vendor/nofuss/client/lib/NoFUSSClient lib/NoFUSSClient
copy vendor/RemoteSwitch-arduino-library lib/RemoteSwitch

The Embedis library is the only one required in all cases. The other three are optional at the moment and will only be linked if you set ENABLE_NOFUSS, ENABLE_EMON or ENABLE_RF in the defaults.h file.

Once you have all the code, you can check if it's working by:

> platformio run -e node-debug

If it compiles you are ready to flash, wire your board like in the flashing section above and:

> platformio run --target upload -e node-debug
> platformio run --target uploadfs -e node-debug

Once you have flashed it you can flash it again over-the-air using the ota environment:

> platformio run --target upload -e node-debug-ota
> platformio run --target uploadfs -e node-debug-ota

When using OTA environment it defaults to the IP address of the device in SoftAP mode. If you want to flash it when connected to your home network best way is to supply the IP of the device:

> platformio run --target upload -e node-debug-ota --upload-port 192.168.1.151
> platformio run --target uploadfs -e node-debug-ota --upload-port 192.168.1.151

You can also use the automatic OTA update feature. Check the NoFUSS library for more info.

Library dependencies are automatically managed via PlatformIO Library Manager or included via submodules and linked from the "lib" folder.

Usage

On normal boot (i.e. button not pressed) it will execute the firmware. It configures the hardware (button, LED, relay), the SPIFFS memory access, the WIFI, the WebServer and MQTT connection.

Obviously the default values for WIFI network and MQTT will probably not match your requirements. The device will start in Soft AP creating a WIFI SSID named "SONOFF_XXXXXX", where XXXXXX are the last 3 bytes of the radio MAC. Connect with phone, PC, laptop, whatever to that network, password is "fibonacci". Once connected browse to 192.168.4.1 and you will be presented a configuration page where you will be able to define up to 3 possible WIFI networks and the MQTT configuration parameters.

It will then try to connect to the configure WIFI networks one after the other. If none of the 3 attempts succeed it will default to SoftAP mode again. Once connected it will try to connect the MQTT server. You can also switch to SoftAP mode by long clicking the on board button or reset the board double clicking the it.

The device will publish the relay state to the given topic and it will subscribe to the same topic for remote switching. Don't worry, it avoids infinite loops.

You can also use "{identifier}" as place holder in the topic. It will be translated to your device ID (same as the soft AP network it creates).

Troubleshooting

After flashing the firmware via serial do a hard reset of the device (unplug & plug). There is an issue with the ESP.reset() method. Check https://github.com/esp8266/Arduino/issues/1017 for more info.

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