ESP 8266 based water controller

Home automation series part 1

As summers are nearing, wanted to go on vacation, now that I have couple of plants that need to be watered when I am on the move.. thought its a good usecase to be automated.

One option is to have timer which can switch on a valve once in a day, however due to power interruption It might loose track unless I build a battery backup for the controller. Other option is to use Realtime clock module to refer and water the plants at specific timing.

Mean time I was checking on node red and IOT and why not build node red hub on Raspberry pi and have controller triggered by node red pipeline. Because its cool (unlike boring clock based implementation) I picked this up with wifi module that I already had (ESP 8266).

First I tried to use node mcu module based on ch340 ttl chip, however it seems getting this serial driver working on Mac or windows is a challenge. So I ordered a separate serial ttl module this module works without any additional drivers on mac or windows.

However node-mcu has many digital pins, given that I have both ESP01 (which has no additional digital output) thought why not use it for this project. After briefly checking on internet got the following tasks

• compile node-mcu firmare
• Using ttl chip program ESP01
• Prepare raspberry image with ssh
  
• Install node-red on raspberry and try out simple flow
• Read about mqtt and figure out a server to run on raspberry
  • Mosquitto seems to be good install service and configure service scripts to start on reboot
  • Test simple mqtt message and node-red flow
• Build the solenoid valve controller board
• Write and upload program to listen to mqtt topic and switch on the valve
  
  

ESP 8266 comes with firmware programmed to be controlled by AT commands. This is easy to get started with serial port, however needs microcontroller to use it in project. So node-mcu was appealing as one can program the esp chip and use micro controller in it. It used simple packed file system and executes init.lua on boot. There are many modules for controlling / interfacing with various modules. There are different versions of ESP modules available such as ESP-01 to 12 with different
spec.

to be continued …