Plant watering with moisture sensor and pump [Workshop]

Plant watering with moisture sensor and pump [Workshop]

1. Overview

This codelab is part of the Viam for educators program, and provides a suggested delivery plan and resources for instructors interested in delivering a hands-on workshop. Take these resources, and make it your own!

Workshop Overview

What You'll Teach

Watch the Demo Video

See a demonstration of the plant watering automation in this video.

Beginner-Friendly: Build an Automatic Plant Watering Robot

Watch the Workshop Recording

See a full-length recording of this workshop for reference.

Plant Watering Workshop | Viam for Educators

2. What participants will need

Review the list of required components (hardware, software), and determine which materials are provided or required for participants to bring on their own. Provide instructions to participants, giving them ample time to prepare and complete prerequisites.

Hardware and supplies requirements

Software and other device requirements

3. Pre-workshop setup for instructors

Learning Objectives

Review the suggested learning objectives, and adjust it according to your goals and audience.

Agenda

Review the suggested agenda, and adjust it according to your goals and audience.

Pre-workshop checklist ✅

Review these setup steps as you're planning the workshop to help prepare for it.

  1. Planning and Logistics

    • Verify equipment inventory: Decide which materials are provided or required for participants to bring on their own. Order any materials and supplies that are provided to participants.
    • Confirm workstation setup: Verify the workshop room layout supports hardware work, such as tables. Ensure participants have power outlets and internet access, as well as water and paper towels in case of a spill. Have spare supplies, such as Raspberry Pis, adapters/readers, and cables, in case of failures. For virtual workshops, confirm logistics for breakout sessions, providing support, and checkpoints.
    • Communicate prerequisites: Share a participant guide prior to the workshop with learning objectives and instructions for installing software and preparing laptops. Provide a checklist for participants to confirm readiness.
    • Establish support channels: Determine how participants can get support for real-time troubleshooting (e.g. Slack or Discord channel for virtual workshops, additional helpers in the room for on-site workshops)
    • Request Viam stickers: Don't forget to request Viam stickers for the workshop.

  2. Content Preparation

    • Prepare workshop teaching materials: Review the Delivery Plan, sample slide deck, and provided resources. Tailor these materials to suit your participants' needs. Decide whether to present them to the group or provide them for independent reference, such as through a web browser or printed handouts.
    • Determine extensibility: During the Hands-on Experiment portion of the delivery plan, there are many options to guide the workshop on a different learning path. Determine if this section will be self-guided exploration, a group exercise, or self-paced learning for participants to explore on their own after the workshop.
    • Prepare code and documentation: Review the provided code and add comments as necessary.
    • Review discussion topics: Review the suggested group discussion topics and adjust for your participants.
    • Review quiz questions: Review the suggested quiz questions and adjust for your participants. Determine if knowledge assessment will be completed throughout the workshop or afterwards.

  3. Dry Run and Testing

    • Test the workshop project: Run through the build following the prepared documentation to ensure it works as expected. Simulate common issues and prepare troubleshooting tips for these scenarios. If physical space is limited, consider sharing supplies.
    • Bring backups: In addition to the backup supplies mentioned earlier during planning.

4. Delivery Plan - overview

During the workshop, instructors can present a customizable slide deck tailored to specific workshop needs. Alternatively, learners can follow step-by-step instructions and checkpoints independently by referencing the pages linked in a web browser.

  1. Hardware Assembly
    • Set up your plant watering components
    • Set up your Raspberry Pi
  2. Software Setup
    • Configure your machine
    • Add your Raspberry Pi
  3. Hands-On Experiment
    • Test the moisture sensor
    • Test the pump
    • Configure a custom service

5. Delivery Plan - Hardware Assembly

Set up your plant watering device

Before programming the Pi to make the plant watering robot functional, you need to physically set up the plant watering robot by wiring the different components together. You will set up the robot to receive signals from the resistive soil moisture sensor and signal to the pump when it is time to pump water from the water's container to the plant's container.

Refer back to this full wiring diagram as you complete the steps to wire your hardware.

Connect your Raspberry Pi to the moisture sensor module:

For connecting the soil moisture sensor to the sensor module, + goes to +, and - to -.

Connect your Raspberry Pi to the relay module:

Last step in the wiring section is connecting the relay and Raspberry Pi to the pump. The wire connectors may be required to connect the jumper wires to the bare wires coming from the pump motor:

Submerge the pump in the cup of water, making sure the wire connectors hang outside the cup and don't touch the water. The legs of the moisture sensor can be placed in the other cup of soil or coffee grounds.

Set up your Raspberry Pi

The Raspberry Pi boots from a microSD card. You need to install Raspberry Pi OS on a microSD card that you will use with your Pi. For more details about alternative methods of setting up your Raspberry Pi, refer to the Viam docs.

Install Raspberry Pi OS

  1. Connect the microSD card to your computer.
  2. Download the Raspberry Pi Imager and launch it.
  3. Click CHOOSE DEVICE. Select your model of Pi, which is Raspberry Pi 4.
  4. Click CHOOSE OS. Select Raspberry Pi OS (64-bit) from the menu.
  5. Click CHOOSE STORAGE. From the list of devices, select the USB flash drive you intend to use in your Raspberry Pi.
  6. Configure your Raspberry Pi for remote access. Click Next. When prompted to apply OS customization settings, select EDIT SETTINGS.
  7. Check Set hostname and enter the name you would like to access the Pi by in that field, for example, planter.
  8. Select the checkbox for Set username and password and set a username that you will use to log into the Pi. If you skip this step, the default username will be pi (not recommended for security reasons). And specify a password.
  9. Connect your Pi to Wi-Fi so that you can run viam-server wirelessly. Check Configure wireless LAN and enter your wireless network credentials. SSID (short for Service Set Identifier) is your Wi-Fi network name, and password is the network password. Change the section Wireless LAN country to where your router is currently being operated.
  10. Select the SERVICES tab, check Enable SSH, and select Use password authentication.
  11. Save your updates, and confirm YES to apply OS customization settings. Confirm YES to erase data on the microSD card. You may also be prompted by your operating system to enter an administrator password. After granting permissions to the Imager, it will begin writing and then verifying the Linux installation to the microSD card.
  12. Remove the microSD card from your computer when the installation is complete.

Connect with SSH

  1. Place the microSD card into your Raspberry Pi and boot the Pi by plugging it in to an outlet. A red LED will turn on to indicate that the Pi is connected to power.
  2. Once the Pi is started, connect to it with SSH. From a command line terminal window, enter the following command. The text in <> should be replaced (including the < and > symbols themselves) with the user and hostname you configured when you set up your Pi.
ssh <USERNAME>@<HOSTNAME>.local
  1. If you are prompted "Are you sure you want to continue connecting?", type "yes" and hit enter. Then, enter the password for your username. You should be greeted by a login message and a command prompt.
  2. Update your Raspberry Pi to ensure all the latest packages are installed
sudo apt update
sudo apt upgrade

6. Delivery Plan - Software Setup

Configure your machine

  1. In the Viam app under the LOCATIONS tab, create a machine by typing in a name and clicking Add machine.
  2. Click View setup instructions.
  3. Install viam-server on the Raspberry Pi device that you want to use to communicate with and automate your plant watering. Select the Linux / Aarch64 platform for the Raspberry Pi to control the rover, and leave your installation method as viam-agent.
  4. Use the viam-agent to download and install viam-server on your Raspberry Pi. Follow the instructions to run the command provided in the setup instructions from the SSH prompt of your Raspberry Pi.

Add your Raspberry Pi

  1. In the Viam app, find the CONFIGURE tab. It's time to configure your hardware.
  2. Click the + icon in the left-hand menu and select Component.
  3. Select board, and find the raspberry-pi:rpi module. This adds the module for working with the Raspberry Pi 4's GPIO pins. Leave the default name board-1 for now.
  4. Notice adding this module adds the board hardware component called board-1.
  5. Click Save in the top right to save and apply your configuration changes.

7. Delivery Plan - Hands-on Experiment

Test the moisture sensor

  1. In the Viam app under the CONTROL tab, you can see the hardware component called board-1. That's your Raspberry Pi that you configured on the CONFIGURE tab.
  2. The module we added has a GetGPIO function to get the digital output of a pin. Enter 40 in the "Pin" field, select the "Read" mode, and click "Get" for the "State" section under "READ PIN". "Low" means there is enough moisture, "High" means the moisture level has fallen below the threshold.

Test the pump

  1. In the Viam app under the CONTROL tab, you can see the hardware component called board-1. That's your Raspberry Pi that you configured on the CONFIGURE tab.
  2. The module we added has a SetGPIO function to set the digital output of a pin. Enter 8 in the "Pin" field, select the "Write" mode, then select "High" and click "Set" for the "State" section under "WRITE PIN". "High" will turn on the pump motor, "Low" will turn it off.

Add the watering-controller service

  1. In the Viam app, find the CONFIGURE tab.
  2. Click the + icon in the left-hand menu and select Service.
  3. Select generic, and find the watering-controller:plant-watering module. This adds the module for automating the water pump based on the digital sensor feedback. Set the name to watering.
  4. Notice adding this module adds the watering-controller service called watering. From the Attributes section of the panel, add the following JSON configuration.
{
       "board_name": "board-1"
}
  1. Click Save in the top right to save and apply your configuration changes.

8. Additional resources and troubleshooting

Additional resources

Common pitfalls and troubleshooting guidance

  1. Safety
    • Be careful when working with water around powered electrical components.
  2. Security
    • Do not share your API credentials publicly.
  3. Flashing firmware
    • Make sure you are using a 5V 3A (25W) power supply.
    • Participants must remember the hostname and username they set while flashing their Raspberry Pi.
  4. Configuring machine and peripherals
    • If any problems occur while setting up the machine and peripherals in the Viam app, check under the LOGS tab to see what might be going wrong.

9. Post-Workshop Resources

Group discussion topics 🗣️

Quiz questions ❓

  1. Hardware Assembly
    • What is the purpose of setting a custom hostname during the Raspberry Pi OS configuration?
    • What hardware signals are used to indicate with the soil moisture is too low?
  2. Software Setup
    • Why is it important to connect your machine to the Viam app during setup?
  3. Hands-on Experiment
    • What is the primary role of viam-server in the system architecture of your plant watering setup?

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