2Pi Microgravity Garden Blog 6 | Water Level Sensor and Bug Catcher inside Rocket !

6 Dec 2020

1 Meter of Pi Blog Posts ...

Blog #1: 2Pi Microgravity Garden Blog 1 | Getting Started | element14 | 1 Meter of Pi

Blog #2: 2Pi Microgravity Garden Blog 2 | Raspberry Pi s... | element14 | 1 Meter of Pi

Blog #3: 2Pi Microgravity Garden Blog 3 | Hello World wi... | element14 | 1 Meter of Pi

Blog #4: 2Pi Microgravity Garden Blog 4 | Software Envir... | element14 | 1 Meter of Pi

Blog #5: 2Pi Microgravity Garden Blog 5 | Connect to Arduino and how plants get pollinated inside rocket without wind???

Blog #6: 2Pi Microgravity Garden Blog 6 | Water Level Sensor and Bug Catcher inside Rocket !

Blog #7: 2Pi Microgravity Garden Blog 7 | AI Image Recognition with Raspberry Pi and Tensor Flow

Blog 6 Task List

Just like previous blogs, the first part is Engineering work and second part is farming

1. Engineering: Try Water Level Sensor

As plants get bigger, they absorb more water and nutrient at faster space. Thinking of astronauts, they want the watering system automated. So, I used a CQRobot Non-Contact Water sensor. I tried other water level sensor but it has some reliability problem meaning the water measurement started failing after 1-2 days. I think having the sensor electronic components close to water can cause a moisture problem. So, I've picked up a non-contact water sensor this time.

Hardware Wiring

Enviro has a GPIO breakout. This breakout includes 5V, 3.3V, I2C (SDA and SCL), GPIO4, and GND pins.

Python Code

I've used RPi.GPIO python package to configure one GPIO which is pin #4.

# External module imports
import RPi.GPIO as GPIO
import time

# Pin Definitons:
water_level_pin = 4 # Broadcom pin 17 (P1 pin 11)

# Pin Setup:
GPIO.setmode(GPIO.BCM) # Broadcom pin-numbering scheme
GPIO.setup(water_level_pin, GPIO.IN) # LED pin set as output

print("Here we go! Press CTRL+C to exit")
try:
    while 1:
        if GPIO.input(water_level_pin): # button is released
            print("water is there")
        else: # button is pressed:
            print("water is not there")
            time.sleep(0.075)
except KeyboardInterrupt: # If CTRL+C is pressed, exit cleanly:
    GPIO.cleanup() # cleanup all GPIO

Demo

If non-contact sensor can see the water thru the container, the LED becomes red and VSCode console on Raspberry Pi indicates that water is there! If not, water is not there.

I've also tried this on sarracenia (bug catcher plant) because this plant constantly requires water.

2. Plant Growth Progressions

This week, green onions. Green onions grow easier with soil because if we add more water than required to the green onions (water level above the roots), they go bad.

3. New Plant: Bag Catchers

Fruits and leafy plants attract bugs. I am not sure how bugs can survive in space rockets. But, it is not fun for astronauts with many bugs in tight area.

So, I've added sarracenia. This plant requires special care. The gardening tips are summarized in this page: https://green-scientist.com/2020/12/05/bug-catcher-sarracenia-catesbaei/