TWR-K60N512-KEIL Freescale Semiconductor, TWR-K60N512-KEIL Datasheet - Page 165

• Manufacturer Part Number: TWR-K60N512-KEIL
• Description: K60N512 Keil Tower Kit
• Manufacturer: Freescale Semiconductor
• Series: Kinetisr
• Type: MCUr

Specifications of TWR-K60N512-KEIL

• Rohs Compliant: YES
• Contents: 4 Boards, Documentation, DVD
• Peak Reflow Compatible (260 C): Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: Freescale Tower System, K60N512

Chapter 17 Touch Sense Input (TSI) Module
defines how many scans with the capacitance above the touch threshold are needed for a
touch to be considered valid. This value can be modified to suit the specific needs of
different applications and electrode sizes.
17.5 TSI hardware implementation
The critical external component for the TSI is the electrode. Electrodes are flat
conductive areas that can be etched into a PCB or drawn with conductive inks on plastic
or crystal. With the GPIO measurement method an external pullup resistor is needed. In
the case of the TSI, the electrode charge is driven by the current sources, therefore there
is no need for an external pull-up resistor. In certain applications where conducted
emissions or ESD is a concern, external protective components can be added. The idea is
to use only a transient voltage suppression (TVS) diode designed for ESD suppression
and a low value (100 - 470 Ω) resistor as protection for current that might flow into the
MCU.
Figure 17-7.
For further information on designing electrodes and in-depth considerations on hardware
and electrode design, search for application notes Designing Touch Sensing Electrodes
(document AN3863) at
www.freescale.com/touchsensing
Kinetis Quick Reference User Guide, Rev. 0, 11/2010
Freescale Semiconductor
165