WithStrings SensorUtils Manual 1. Description SensorUtils is a utility
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1. WithStrings SensorUtils Manual 1 Description SensorUtils is a utility program built around the notion of a strip chart recorder Inputs to the recorder are sensors built into the Android device The recorder displays graphically the sensor readings on a strip chart like graph There are three channels on the recorder that can used for each sensor The strip chart graph can be saved as a screen shot and data collected can be saved to a file Figure 1 shows the layout of the user interface and available controls Q 3 Gl 14 45 Sensorutils Sensor BMA150 3 axis Accelerometer Selection Numeric Display ECE EEE Pens Up Down r a Strip chart Rate Width Chart Max 10s Controls Mag Interp Chart X10 Line Clear A 11933 MB free Messages Figure 1 SensorUtils User Interface recording turntable acceleration 33 333 rpm gt 25 ai E 17 04 SensorUtlis BMA150 3 axis Accelerometer 0 436 m s2 0 449 m s2 0 041 m s2 0 2504 sec Rate Width Mag Interp Max 105 X20 Lin Monitor Record Zero 0 000 0 220 Figure 2 Turntable test with orientation Arrows 2 Operation Launch the application SensorUtils will query your device for available sensors One sensor will be shown on the selection button Each time the button is clicked another sensor is shown The button will eventually return to the first sensor displayed Typical of physical measurements available include acceleration magne2. a multiple of 1 2 or 5 The range can be magnified up to 100 6 Interpolation Line Step The strip chart will normally draw a straight line between points although there is no data between points Using step mode will keep displaying the same value for a point until new data is captured See figure 5 for an example 7 Clear Clear chart The cleared chart will not be seen unless monitoring is active Clearing the chart has no effect on data recording to a file 8 Monitor Pauses capturing of data to the chart and file A new file is created every time the system is paused and recording restarted 9 Record Data is recorded to a file on the SD card in the following directory mnt sdcard Android data com withstrings sensorutils files Recording Stops when monitoring 1s deactivated a different sensor is selected or a phone event pushes SensorUtils to the background A new file is created when recording is restarted The data file has comma separated values CSV The file is named YYYY MM DD HH MM SS csv Figure 3 Data recording requires a writable SD card Data is removed when SensorUtils is uninstalled Up to four columns are recorded dt time between readings X Y and Z depending on the sensor and pen controls The zero value is subtracted from X Y and Z data Pens may be Lifted or lowered while recording but column headings are not changed and values will fill columns starting at the left In the case of t
3. channel The width magnification interpolation clear and zero buttons affect how data is displayed on the chart A screen shot can be captured by pressing on the chart area when the monitor button is deactivated The screen shot is saved to a jpeg file in the mnt sdcard Pictures directory The format for the file name is YYYY MM DD HH MM SS jpg File size is less than 100KB Figure 4 If the device is attached through a USB connection to a host computer the SD card will not be available for writing Screen capture requires that the SD card is writable Buttons 1 Sensor Selection Increments through available sensors that have been made available to the Android operating system This is manufacturer and model specific 2 Pens Pen up down allows recording for the channel either to the strip chart or file The pen can be lifted during recording Sensors that have only one output will only have one pen available 3 Rate Mask Maximum available data rate allowable by the Android device or masked rate Masked rate allows only one sample per period specified Other running applications may affect the data rate 4 Width Seconds of virtual paper on the chart Data will fall off the chart when the number of seconds specified by the width is reached The width does not affect data recored to a file 5 Mag The y axis on the graph is nominally set to the range queried from the selected sensor modified to a nice number
4. he X pen Lifted recording X Y and Z initially the Y values will be under the X column and Z values will be under the Y column 10 Zero When monitoring data pressing the zero button will subtract the latest readings at the time the button is pressed from subsequent readings This is useful for removing offsets File Edit View Insert Format Tools Data Window ae CETERE Arean F Liberation Sans MIE A A A Z alii Pa al E fi gt BMA150 3 axis Accelerometer 01 18 2014 at 02 46 22 PST 01 18 2014 at 02 46 22 PST ff BMALSO E Acceleromete 0292659998 0 2096250057 0 2678219974 0 3257749975 0 35495001 08 Data 0 04086104333 0 490332514 05911935544 05720546246 05720546246 05911035544 Q 5306699872 Q 4086104333 ar ae m a Figure 3 Strip chart screen shot AL h om i mim Bi Data 4 2530719042 4 1713498831 4 0215260983 0 9806650281 0 9534243345 1 AT17072549 Directory Location imnt sdcard Android data com withstrings sensorutils files O 721876469 0 1059630127 0 5598139763 B 3813697398 E 6401563287 1089630127 Be a ane a m d Z Data 02587862015 0 1089630127 0 1089630127 01498241495 01498241495 1498941 495 Directory mnt sdc ard Pictu res Figure 4 Screen shot of screen shot 35 nl e 17 07 Sensorutils CM3602 Proximity sensor X 9 000 cm dt 0 3617 sec Rate Width Mag In
5. terp Chart Max 10s X1 Line Clear 0 000 0 362 35 u 17 07 Sensorutils CM3602 Proximity sensor Rate Width Mag Interp Chart Max 10s X1 Step Clear 0 000 0 542 Figure 5 Interpolation Line Step 3 Characteristics Operating System Android Minimum API 9 Gingerbread Permissions WRITE EXTERNAL STORAGE Acquisition Rate Dependent on device SensorManager SENSOR DELAY USER Resolution Sensor Dependent Settings Sensor Selects sensors available on device Rate Max Acquisition Rate Mask 0 1 to 10 seconds one shot per interval Interpolation Line or Step File Format CSV the data is not interpolated Chart Horizontal Range 1 to 600 seconds Chart Vertical Magnification Sensor Range X1 to X100 Zero removes offset at time pressed in Monitor mode Clear clears chart in monitor mode Record Writes data to a file monitor mode Columns are based on Pen selection X Pen Y Pen Z Pen provides pen up or pen down like functions Identity sin u sin v 1 2 sin u v sin u tv Graphics Design N Dynamite 2014 Todd Merport
6. tic field orientation proximity light intensity and barometric pressure Figure 2 shows the orientation of the device in relationship to its sensor coordinate system Note that the data is returned by the device to the SensorUtils application asynchronously The device will return the data at the rate that it sees fit in order to let other applications perform properly SensorUtils may be interrupted by an incoming call or an user action if the SensorUtils application is off the screen any recording in progress in be saved and the application will release any requests for sensor data Users also need to consider that other applications make use of the sensors The effect of this is that the rate that SensorUtils receives updates decreases perhaps significantly Please read information the Android developer document Sensors Overview for more Display Areas 1 Numeric Readout This readout shows zeroed numeric sensor data There are four rows in the readout The first three rows have columns axis data and unit for each of the axes The forth row shows the time between the current and previous reading delta time dt 2 Strip chart Data is displayed graphically in a two dimensional graph Newest data is written on the right side of the display and pushed to the left as new data arrives Three virtual pens write on the graph in different colors The pen lift button can deactivate writing on the chart for its assigned
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