Inductive Touch Sensing Keyboard Circuit

Figure shows an example for a 4-key Inductive Touch Sensing keyboard
with key controlled by the IO pins of the PIC® MCU.

The PIC® microcontroller is used to generate a squarewave signal and
to do all the necessary operations forproper detection of the key press event.

Then, RIN-CIN filter converts the square wave output ofthe PWM into
a quasi-triangular waveform.

To calculate the amplitude of the triangular signal, thestandard charging
time equation for an RC network willbe used

MCP2036
DescriptionThe MCP2036 Inductive Sensor Analog Front End(AFE)
combines all the necessary analog functions fora complete inductance
measurement system.The device includes :• High-frequency,
current-mode coil driver forexciting the sensor coil.• Synchronous detector
for converting AC sensevoltages into DC levels.• Output amplifier/filter to
improve resolution andlimit noise.• Virtual ground reference generator for
singlesupply operation.

Features
• Complete Inductance Measurement System:
- Low-Impedance Current Driver
- Sensor/Reference Coil Multiplexer
- High-Frequency Detector
• Operating Voltage: 2.7 to 5.5V
• Low-Power Standby Mode
• Gain and Frequency set by external passivecomponents

MCP2036 Datasheet pdf
http://ww1.microchip.com/downloads/en/DeviceDoc/22186A.pdf

Introduction to Inductive Touch Sensing Vedio

Introduction to mTouch Inductive Touch Sensing Part 1



Introduction to mTouch Inductive Touch Sensing Part 2