Making Plots Using Excel

shaker response - 300Often, it's useful to plot data gathered by a microcontroller system.  Data might be temperature vs time, voltage vs current or any other information.  An X - Y plot can aid in understanding information.  Microsoft Excel can easily polt many types of data.

The first issue is getting the desired data from a microcontoller system.  The usual method is to capture a data stream in a terminal emulator and to save the data in a file.  A little forethought in microcontroller programing will make plotting easier.  A common format is CSV or comma-separated-values.  Each x-y pair is one a single line, separated by a comma and the line is terminated with a carriage return (chr$(13)) and a line feed (chr$(10)).  The captured data file will look something line this:




Files formatted like this are easily imported into Excel.

Start Excel and open the text file.  You'll see a screen something like this:

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Select the delimited option and the screen will change to this:

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Check comma as the delimiter and click next.  The data will be placed in two columns representing x and y values.

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Now that the hard part is done, select the data for the graph.

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Next, click INSERT on the menu bar and select SCATTER PLOT.

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The scatter menu shows several options - straight lines between points, curve-fit lines and markers or not.  Select the desired format.  Be sure to select the SCATTER option rather than the LINE option.

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A small version of the plot will be shown on the sheet.  Right-click in the body of the graph, select NOVE GRAPH and choose new sheet.

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The graph will be created full size in its own sheet.  Next, right-click in the axes to change scaling.  I like to choose fixed scaling to maximize plot area.  If several graphs are to be compared, it's best to fix the scaling the same on each for easy comparison.

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Finally, with a little editing is the final graph.

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The process is pretty simple.  There are a lot of options to be investigated to achieve the look you want.

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