GardeningBot

Yet another gardening bot based on ESP8266 NodeMCU v3

Requirements

• The gardening system should water a single plant.
• When watering, a telegram message should be sent (using WiFi) to notify this event. Additionally, the telegram message should report the soil mosture level before and after watering.
• The system should water the plant every X hours.
• The system should be powered by a cheap USB power bank and last at least a couple of weeks.
• The system should pump the water from a 5L water tank (placed 1 meter below the plant)

Hardware

• ESP8266 NodeMCU v3 ($3 on AliExpress)
  
• Water Pump QR30B DC 5V 2.3W 220L/H ($6 on AliExpress)
  
• PowerBank 2200mAh PURO BB22C1WHI (€6 on Ebay): no led when discharging, powered on even when current drain is few mA
  
• Capacitive Soil Moisture Sensor ($1.5 on AliExpress)
  
• 2 x 1A 1000V Diode 1N4007 ($0.60 x 100 pcs on AliExpress)
  
• 2 x BC337 BJT ($3 x 200 pcs on AliExpress)
  
• 40x60mm FR-4 2.54mm Double Side Prototype PCB (€1 on Ebay)
  
• 2 x Aluminum electrolytic capacitor 470uF (€4 x 120 pcs on Ebay)
  
• Multilayer Ceramic Capacitor 10pF + 100nF (€4 x 120 pcs on AliExpress)
  
• Water Tank 5L
  
• Kit DIY Micro Drip Irrigation System (€8 on Wish)
  
• Clear Airtight Lunch Box (€2)
  
• Jumper wires + resistors

Software

See source code WifiGardeningBot.ino

Result

System #1

System #2

Notes

• ESP8266 NodeMCU v3 has a lower power usage (~1.8mA) when in deep sleep mode compared to NodeMCU v1 and NodeMCU v2. On v1 and v2, you need to remove the power regulator to get a small power usage in deep sleep. With a ~1.8mA current drain, you get more than 2 weeks when using a 2200mAh power bank.
• Soil Moisture Sensors that measure resistance give totally unreliable readings just after 1-2 months. Avoid them. Capacitive soil sensors are better, but still sometimes unreliable. After many and long experiments, I have used capacitive sensors but only to get feedback (via telegram messages) about the soil moisture. The readings are NOT used by the system to decide whether it is the right time to activate the water pump. If you want to build a system that waters a plant based on the soil mosture level then you need to buy reliable (=professional) but expensive sensors.
• Finding (cheap) power banks that: (i) do not waste power (e.g., flashing LEDs) and (ii) keep working even with a very low current load is really hard.