Datasheet

23
Easy24-33 v6 Development System
MikroElektronika
page
19.0. Touch Sense Keypad
The Easy24-33 v6 development system is provided with a set of touch sensitive buttons making the navigation touch sense keypad.
The touch sense buttons are arrow-like oriented left, right, up and down. There are also two additional push buttons marked as E and
C that can be assigned ENTER and CANCEL functions, respectively. Touch sense buttons are connected to push buttons having
the same names that are also connected to the microcontroller’s port PORTB. Their function is determined by the programmer while
writing program for the microcontroller.
The operation of the touch sense buttons is based on the sensor capacitance change. A touch sense button consists of a small copper
surface connected to the microcontroller pin. Around this button, there is a copper surface connected to the ground. These two isolated
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on the microcontroller pin to be changed as well. Touch sense buttons are connected to the microcontroller via its pins connected to
the built-in A/D converter. Some microcontrollers feature a special CTMU module (Charge Time Measurement Unit) used to measure
changes in capacitance. This module can also be used to measure exact time, relative capacitance changes as well as to generate
pulses independently from the oscillator.
Figure 19-2: Touch sense keypad and microcontroller connection schematic
)LJXUHTouch sense keypad
Have in mind when writing
program for the microcontroller
that touch sense keypad is
connected to port PORTB
The operation of the touch sense buttons is based on the capacitance change
127( Make sure that pull-up/pull-down resistors on pins RB0, RB1, RB2, RB3, RB12 and RB14 are disabled prior to using the
touch sense keypad.
It is surrounded by another
copper surface connected to the
ground
Copper surface is connected to
the RB12 microcontroller pin