pxt-calliope/docs/lessons/charting/activity.md

charting activity

Measure the acceleration on the micro:bit in the "z" direction.

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Welcome! This activity will teach how to use the 1st micro:bit to chart the second micro:bit's acceleration in the "x" direction. Let's get started!

Let's measure acceleration (mg) and then send number. Acceleration is measured in milli-gravities, so a value of -1000 is equivalent to -1g or -9.81m/s^2. We will be able to get the acceleration value (g-force), in the specified "x" dimension. Send number will broadcast a number data packet to other micro:bits connected via radio.

radio.sendNumber(input.acceleration(Dimension.X));

We want to display the acceleration forever. In order to do so, we need a forever loop. A forever loop will repeat code in the background forever.

basic.forever(() => {
    radio.sendNumber(input.acceleration(Dimension.X));
});

We want to register code to run when a packet is received over radio. We can implement this code by adding on data received.

basic.forever(() => {
    radio.sendNumber(input.acceleration(Dimension.X))
})
radio.onDataReceived(() => {
    
})

Finally, we want to chart the acceleration. So we must first implement plot bar graph. Plot Bar Graph will display a vertical bar graph based on the value and high value. In order to transfer the receive the number from the 1st micro:bit, we must implement receive number to constantly display a vertical bar graph based on the value. Remember, the value will equal to the micro:bit's acceleration in the "x" direction.

basic.forever(() => {
    radio.sendNumber(input.acceleration(Dimension.X))
})
radio.onDataReceived(() => {
    led.plotBarGraph(radio.receiveNumber(), 1023)
})

• Connect the first micro:bit to your computer using your USB cable and run the charting script on it.
• Connect the second micro:bit to your computer using your USB cable and run the charting script on it.
• The first person and second person take turns tilting the micro:bit in the "x" direction while the other player charts the data on the micro:bit!