Using the mTouch™ Sensing Solution
©
2008 Microchip Technology Inc.
DS51748A-page 17
The upper portion of the Setup dialog allows the user to set individual values for the
Guardband and Trip Point for each sensor channel. Users may optionally set additional
reference points, labelled “Aux1” and “Aux2”. All four variables have a valid range of 0
to 65535. Each point has an additional “Visible” checkbox that determines if the value
is to be displayed on the bar graph.
The “Scale” area of the dialog is used to manually scale the bar graph. Values for the
lower limit (LL) and upper limit (UL) of the bar graph may be directly entered in the text
boxes provided; they may be set using the slider and/or bump arrow under the boxes.
As with the other set points, values for LL and UL are valid from 0 to 65,535 (provided,
of course, that UL is always greater than LL). The
Autoscale R1
button automatically
selects the minimum and maximum values to be displayed for the bar graph.
FIGURE 3-5:
SENSOR DISPLAY SETUP DIALOG BOX
3.2.2.3
SENSOR DATA CHARTING AND LOGGING
Within the Setup window, the
Chart R1
button enables data recording from any sensor
channel. Clicking on
Chart R1
opens an additional window (Figure 3-6) that displays a
plot of the channel’s conversion value versus time. Plotting of data begins immediately
when the
Chart R1
is pressed, and continues to plot as long as the
Run
checkbox in
the Plot window is selected; pressing the
Clear
button erases the plot and begins a new
plot in the same window.
The range of the touch sensor values on the chart are equal to the minimum and
maximum values set for the bar graph. Data for the plot window is sampled and
displayed at a minimum rate of 10 samples per second. The amount of data displayed
(and effectively, the scale of the time axis) is changed by changing the value in the
Num
Points
text box. By default, the number of data points is 500.
The
Log Data
checkbox enables automatic logging of the channel’s data to a text file
(
.txt
extension). The filename is the touch sensor channel name with the
.txt
extension. When the checkbox is selected, a dialog pop-up appears to confirm the file
name (generally,
<channel-name>.txt
) and working directory (
C:\Program
Files\ Microchip\mTouch2
). Data is logged to the file at the same rate as it is
plotted (5 samples per second).
Note 1:
The
Use Saved Values
option button must be set for these values to
be valid and used by the demo board. See
for further information.
2:
“Aux1” and “Aux2” are not available on the initial version of the mTouch
sensing solution.
