Cat Napping

1. Introduction

Lychee the cat loves the sun and wants to know if your home has a good sunbathing spot. Are you up for the challenge?

2. Setting logging to false on start

📋 Variable data 📋

First, we want to make sure we know when our micro:bit is collecting data. To do this, let’s create a boolean variable and use it to track when the micro:bit is logging data. We’ll start with the logging variable set to false.

► In the ||variables:Variables|| category, click on Make a Variable... and make a variable named logging.

► From the ||variables:Variables|| category, grab the ||variables:set [logging] to [0]|| block and snap it into the empty ||basic:on start|| container.

► From the ||logic:Logic|| category, grab a ||logic:<false>|| argument and snap it in to replace the ||variables:[0]|| value in your ||variables:set [logging] to [0]|| statement.

let logging = false
logging = false

3. Toggle logging on A press

▶️ Starting and stopping ⏸️

Let’s give Lychee some control over when she wants to start and stop logging data on the micro:bit.

► From the ||input:Input|| category, grab a ||input:on button [A] pressed|| container and drag it into your workspace.

► From the ||variables:Variables|| category, grab a ||variables:set [logging] to [0]|| block and snap it inside of your ||input:on button [A] pressed|| container.

► From the ||logic:Logic|| category, grab a ||logic:<not []>|| argument and snap it in to replace the 0 argument.

► From the ||variables:Variables|| category, grab a ||variables:logging|| variable and snap it in to replace the empty ||logic:<>|| in the ||logic:not <>|| statement.

✋🛑 Take a moment to help Lychee answer the following question: What is happening every time she presses the A button?

let logging = false
input.onButtonPressed(Button.A, function () {
    logging = !(logging)
})

4. Visual logging indicators

👀 Visual indicators 👀

It would help to know when the micro:bit is logging data and when it isn’t. For this step, we will be building out a visual indicator using an if then / else statement.

► From the ||logic:Logic|| category, grab an ||logic:if <true> then / else|| statement and snap it in at the bottom of your ||input:on button [A] pressed|| container.

► From ||variables:Variables||, grab a ||variables:logging|| variable and snap it in to replace the ||logic:<true>|| condition in your ||logic:if then / else|| statement.

► Let’s display an image when the micro:bit is logging data. From the ||basic:Basic|| category, grab a ||basic:show icon []|| block and snap it into the empty top container of your ||logic:if then / else|| statement.

► Set it to show the “target” icon (it looks like an empty sun - scroll down to find it!). This will show whenever your micro:bit is collecting data.
💡 In the show icon dropdown menu options, you can hover to see what each design is called.

let logging = false
input.onButtonPressed(Button.A, function () {
    logging = !(logging)
    if (logging) {
        basic.showIcon(IconNames.Target)
    } else {
    }
})

4. Auditory logging indicators

Let’s now add an auditory indicator that your micro:bit is logging data!

► From the ||music:Music|| category, grab a ||music:play sound [giggle] [until done]|| block and snap it into the bottom of the top container of your ||logic:if then / else|| statement.

► Click on the giggle dropdown and select hello. Your block should now say ||music:play sound [hello] [until done]||.

► Let’s clear the board when the micro:bit is not logging data. From the ||basic:Basic|| category, grab a ||basic:clear screen|| block and snap it into the empty bottom container of your ||logic:if then / else|| statement.

let logging = false
input.onButtonPressed(Button.A, function () {
    logging = !(logging)
    if (logging) {
        basic.showIcon(IconNames.Target)
        music.playSoundEffect(music.builtinSoundEffect(soundExpression.hello), SoundExpressionPlayMode.UntilDone)
    } else {
        basic.clearScreen()
    }
})

5. Time interval for data logging

📈 A data point a minute 📈

Let’s set up the data logging for Lychee! In order to get Lychee a good amount of data without running out of memory, we should collect one data point for her every minute.

► From the ||loops:Loops|| category, grab a ||loops:every [500] ms|| container and add it to your workspace.

► Click on the the 500 dropdown and select 1 minute.
💡 1 minute is equivalent to 60000ms, which is what the number will automatically change to.

loops.everyInterval(60000, function () {
})

6. Setting up a logging variable

Now, let’s use an if then statement to track when the micro:bit is logging data.

► From the ||logic:Logic|| category, grab a ||logic:if <true> then|| statement and snap it into your ||loops:every [600000] ms|| container.

► From the ||variables:Variables|| category, drag out a ||variables:logging|| variable and snap it in to replace the ||logic:<true>|| argument in the ||logic:if <true> then|| statement.

let logging = false
loops.everyInterval(60000, function () {
    if (logging) {
    }
})

7. Setting up logging - Part 1

🏁 Ready…set…log! 🏁

Lychee loves her sun spots because they provide a nice, sunny and warm place to nap. So, we’ll need to measure the temperature and light in different places around the house.

► From the ||datalogger:Data Logger|| category, grab a ||datalogger:log data [column [""] value [0]] +|| block and snap it inside the ||logic:if [logging] then|| statement.

► Click on the "" after the word column and type in “temp“.

► From the ||input:Input|| category, select the ||input:temperature (°C)|| parameter and drag it in to replace the 0 after the word value.

let logging = false
loops.everyInterval(60000, function () {
    if (logging) {
        //@highlight
        datalogger.log(
            datalogger.createCV("temp", input.temperature())
        )
    }
})

8. Setting up logging - Part 2

► On the right of the ||input:temperature (°C)|| input that you just snapped in, there is a ➕ button. Click on it. You should now see a new row that says ||datalogger:column [""] value [0]||.

► Click on the empty "" after the word column and type in “light“.

► From the ||input:Input|| category, select the ||input:light level|| parameter and drag it in to replace the 0 parameter after the word value.

let logging = false
loops.everyInterval(60000, function () {
    if (logging) {
        //@highlight
        datalogger.log(
            datalogger.createCV("temp", input.temperature()),
            datalogger.createCV("light", input.lightLevel())
        )
    }
})

9. Time to log data!

🎉 Time to log data! 🎉

You did it! If you have a micro:bit V2 (the one with the shiny gold logo at the top), download this code and try it out!

► Find a sun spot in your house and press the A button to start logging data - your display should show an icon and play a sound to indicate that you are logging data.

► After some time (we recommend at least an hour), press the A button again to stop logging data - your display should clear to indicate that you are not logging data.

10. Reviewing your data

🕵️ Reviewing your data 🕵️

Now that you have logged some data, plug your micro:bit into a laptop or desktop computer. The micro:bit will appear like a USB drive called MICROBIT. Look in there and you’ll see a file called MY_DATA:

Double-click on MY_DATA to open it in a web browser and you’ll see a table with your data:

11. Lychee’s preferences

Does your home have a good sunbathing spot for Lychee? Compare the light and temperature levels you record for different areas around your house! The sunniest and warmest spots will likely be her favorite ☀️😻

datalogger