The Edge Devices - Sonoff, ESP8266 and Tasmota

Sonoff, ESP8266 and Tasmota, how are these 3 components related? This can be viewed as a computer where Sonoff is the computer, ESP8266 is the CPU and Tasmota is the Operating System.

Sonoff is one of many companies in China which manufactures smart home WIFI connected devices such as switches, plugs and lights. Their devices are very popular among DIY smart home builders because they make it convenient to flash custom firmware. I have bought a few of such devices, Basic Switch, RF-Wifi Switch, Wall socket and Light Switch. This can be easily found on Aliexpress, Taobao and Banggood, Videos and articles on how to modify to custom firmware can be found on Youtube.

ESP8266 is one of the amazing makers modules that come out after Arduino. Espressif has make the ESP Microcontroller programmable using the Arduino IDE. The library has the entire TCP stack built in making it possible to be programmed as a mini web server, tcp/udp server/client. There a complete library available which make this task a lot easier.

Tasmota is an open source project created by arendst. The software that allowed Sonoff hardware and ESP8266 based modules to have unlimited interfacing capabilities using minimal programming effort. It has OTA capability, MQTT connectivity and a web interface to configure the module. Kudos to him to be able to squeeze so much functionalities into a 1 MBits flash, that is 128kb of flash.

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Using ESP-Link transparent bridge (ESP-01 and Arduino Pro Mini)

Recently stumbled across an interesting open source project ESP-Link . Its main purpose is to network-enable a non-network microcontroller (MCU) such as Arduino Uno, Pro mini or Nano using ESP8266. The author termed it as "Transparent Bridge". The ESP and MCU communicate via the serial link and there is a companion Arduino library EL-Client for the MCU to connect up the network using MQTT, REST, TCP and UDP. Setup I have put together an ESP-01 and an Arduino Pro Mini for this experiment. I have chosen a 3.3 version Pro mini so that I do not need to do any voltage level shifting between the I/O pins. In order to have a stable voltage source, the ESP8266 is powered by Pro Mini and the Pro Mini "RAW" pin is connected to a 5v USB power source. The RAW pin can take voltage up to 12V. The reset pin of Pro Mini is connected to GPIO 0 of ESP-01. This enables the ESP-01 to reset the Pro Mini. I have linked up an APDS 9960 sensor to it and periodically se...

Using ESP-Link transparent bridge (ATmega2560+ESP8266 board)

I have found this interesting board selling on Aliexpress website. It is an Arduino Mega 2650 with a built-in ESP8266 which allows the Mega to connect to wifi. This board has cut down a lot of wiring and bring out interesting possibilities. One of this is to connect up both the microcontrollers using ESP-link firmware. I have an earlier blog post that described how to wire up an ESP-01 and Arduino Pro Mini. One of the tricky parts in this setup is the sequence of flashing the ESP firmware. Flashing the onboard ESP8266 requires some setting changes to the dip switches. The following are the sequences which I get both the microcontrollers to talk to each other. Set the jumper 5,6,7 to ON and the rest OFF. This will set the ESP to update mode. I am using version 3.0.14 and flashed the ESP using the following parameters: esptool --port com26 --baud 230400 write_flash -fm dio -fs 4MB -ff 80m 0x0 boot_v1.6.bin 0x1000 user1.bin 0x3fc000 esp_init_data_defa...

DIY Sonoff RF Bridge

Tasmota recently supported the RF bridge by iTead which allowed for RF 433 remote devices to be controlled/controlling using Sonoff products. e.g A handphone can be used to control a remote RF device or an RF remote control can use to control a WIFI enabled device. By using Tasmota, I can control the device using MQTT. This idea fits exactly to my smart home plan. Here is the schematic: I cheated a bit by having ESP01 mounted on a breakout board. This breakout board converts all the external pins to 5v which simplified the wiring and I do not need to use a voltage level shifter. Moreover, the Arduino 3.3v power does not have enough current to power the ESP reliably and I have to power it via the 5V from Arduino Uno. Next, I used an Arduino Uno prototype shield with a tiny breadboard to hold all the components together. For the RF 433 transmitter/receiver, I am using the development kits when I purchased the all-in-one Arduino development kits. An antenna is added for m...

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