Archived:Retrieving accelerometer values in m

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M on Symbian is not maintained and may not run on current Symbian versions. All M articles have been archived.

Article Metadata

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Tested with

Devices(s): Nokia N95, Nokia 5800 XpressMusic

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Compatibility

Platform(s): S60 3rd Edition, S60 5th Edition

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Platform Security

Capabilities: )

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Article

Created: bogdan.galiceanu (24 May 2009)

Last edited: hamishwillee (09 May 2013)

Overview

This article shows how to retrieve accelerometer data in m.

Preconditions

Note: The accel module is only available in S60 3rd Edition and later.

Source code

use accel
 
 
//Get the data for the 3 axes
values = accel.get()
 
//Display it
print "X: " + values["x"]
print "Y: " + values["y"]
print "Z: " + values["z"]

Postconditions

The values from the accelerometer are displayed.

Practical use: detecting shakes

As more and more devices are equipped with an accelerometer sensor it is becoming a frequent practice to make applications that respond to the user shaking the phone. The following code examplifies how to implement such a feature.

It should be noted that, according to the m documentation, values returned by the get function vary from one device to another and are rather unstable. A great deal of tweaking should be done in order to ensure decent functionality.

use accel, math
 
 
while true do
	x = false;
	y = false;
	z = false;
	//Read the initial values
	values = accel.get();
	//Wait until one of the values changes by at least 140 points
	accel.new(140);
	//Acquire new values
	new_values = accel.get();
	//See which one changed
	if math.abs(new_values["x"] - values["x"]) >= 140 then x = true
	elsif math.abs(new_values["y"] - values["y"]) >= 140 then y = true
	elsif math.abs(new_values["z"] - values["z"]) >= 140 then z = true
	end;
	//Wait for the phone to return to the initial position (meaning approximately the same accelerometer values)
	//with a margin of error and within a reasonable time interval (2000 milliseconds, for example)
	accel.new(120, 2000);
	//Acquire new values
	new_values = accel.get();
	//Check if the necessary one changed and if so, print the message
	if x = true then delta = new_values["x"] - values["x"]
	elsif y = true then delta = new_values["y"] - values["y"]
	elsif z = true then delta = new_values["z"] - values["z"]
	end;
	try
		if math.abs(delta) <= 50 then print "Shake detected!" end;
	catch exc by
	end;
end