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

Challenge

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Welcome! The activity will teach you how to use the acceleration of the 1st micro:bit and to visualize the acceleration on the 2nd micro:bit. Let's get started!

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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));

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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));
});

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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(() => {
    
})

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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)
})

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Notice that moving the micro:bit the farthest direction in the x direction will be -1023 on the charting beneath the simulator. The second observation will be that the LEDs will be full brightness on the 2nd micro:bit. There is a single LED turned on with the 1st micro:bit. Additionally, the graphs will reflect 0 acceleation for the 1st micro:bit. In this scenario, if you are adjusting the acceleration in the simualator, you are also changing your chart that will be produced.

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NOTE: The colors of the charts reflect the color of the micro:bit simulator. In this instance, the micro:bits are blue and green. So the colors of the line graphs reflect the colors of the micro:bit

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After running this simulation several seconds by moving the micro:bit side to side in the x direction, you are ready to graph or chart the accceleration of the micro:bit. We want a printout of our acceleration on Excel. We will graph the fluctuating acceleration of the simulation experiment.

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Finally, you must open the Excel CSV file by clicking on the data.xls file that was downloaded to Downloads Folder.

Use the Recommended Charts command on the Insert tab to quickly create a chart that’s just right for your data.

• Select the data that you want to include in your chart.

• Click Insert > Recommended Charts.

• On the Recommended Charts tab, scroll through the list of chart types that Excel recommends for your data. Pick the scatter plot.

• Use the Chart Elements, Chart Styles, and Chart Filters buttons next to the upper-right corner of the chart to add chart elements like axis titles or data labels, to customize the look of your chart

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Have fun reviewing your simulation and analyze the acceleration by chart the Excel data using Excel.

• 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!
• Review and analyze the actual micro:bit device acceleration data on Excel
• Display acceleration with y or z using plot bar graph by changing acceleration from "x" to "y" or "z"