Introduction: SINGLE TOUCH SWITCH MODULE

-by Maninder Bir Singh Gulshan and Bhawna Singh

Step 1: ​Touch Sensor

Description

The TTP223 Touch Key Module is based on a touch-sensing IC (TTP223) capacitive touch switch module. A capacitive touch sensor module based on the dedicated TTP223 touch sensor IC. The module provides a single integrated touch sensing area of 11 x 10.5mm with a sensor range of ~5mm.

An on-board LED will give a visual indication of when the sensor is triggered. When triggered the output of the module will switch from its idle low state to high (default operation). Solder jumpers allow for reconfiguring its mode of operation to be either active low or toggle output.

TTP223 Capacitive Touch Sensor Module. The TTP223 is a touchpad detector IC replicating a single tactile button.

The TTP223 is a touchpad detector IC replicating a single tactile button. This touch detection IC is designed for replacing traditional direct button key with diverse pad size.

Trigger-setting mode: (1 -> Short; 0 -> No Short)

AB=00: No-lock High TTL level output;

AB=01: Self-lock High TTL level output;

AB=10: No-lock Low TTL level output;

AB=11: Self-lock Low TTL level output;

Step 2: Features and Circuit Diagram

  • Simple to Use, Auto Calibration
  • Output Status Indicator LED
  • Output can configured be Active High or Low
  • Output Mode can be configured to Toggle or Momentary
  • Easy to replace mechanical key outputs
  • Output can be directly connected to Microcontroller's Input pins
  • Supports momentary or latching/toggle modes.
  • Supports Active High or Active Low output signal modes.
  • Dimensions: 15mm x 11mm.
  • Input Voltage: 2 Volt – 5.5 Volts DC.
  • The response time max ~ 60mS in fast mode, ~220mS at low power mode @VDD=3V.
  • Sensitivity can adjust by the capacitance (0~50pF).
  • Have two kinds of sampling length by pad option (SLRFTB pin).
  • Stable touching detection of the human body for replacing traditional direct switch key.
  • Provides Fast mode and Low Power mode selection by pad option (LPMB pin).
  • Provides direct toggle mode by pad option (TOG pin).
  • Open drain mode by bonding option, OPDO pin is open drain output, Q pin is CMOS output.
  • All output modes can be selected active high or active low by pad option (AHLB pin).
  • Have the maximum on time 100sec by pad option (MOTB pin).
  • Have external power-on reset pin (RST pin).
  • After power-on have about 0.5sec stable-time, during the time do not touch the keypad, and the function is disabled.
  • Auto calibration. Re-calibration period is about 4.0 sec when the key has not be touched.

Step 3: 5V Relay Module

Step 4: Components Required

TTP223 IC

The TTP223 is a touch pad detector IC which offers 1 touch key. The touching detection IC is designed for replacing traditional direct button key with diverse pad size. Low power consumption and wide operating voltage are the contact key features for DC or AC application

Step 5:

SMD Capacitor with 104 and 106 value

104 stands for 100nF and 106 stands for 10nF.

Step 6:

SMD resistor 121 value

121 stands for 120ohm

Step 7:

BC547 transistor

It is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current. A small current at its base controls a larger current at collector & emitter terminals.

BC547 is mainly used for amplification and switching purposes. It has a maximum current gain of 800. Its equivalent transistors are BC548 and BC549.

The transistor terminals require a fixed DC voltage to operate in the desired region of its characteristic curves. This is known as the biasing. For amplification applications, the transistor is biased such that it is partly on for all input conditions. The input signal at base is amplified and taken at the emitter. BC547 is used in common emitter configuration for amplifiers. The voltage divider is the commonly used biasing mode. For switching applications, transistor is biased so that it remains fully on if there is a signal at its base. In the absence of base signal, it gets completely off.

Step 8:

Diode IN4004

  • 0002-Mounting: Through hole
  • 1034-Housing: DO41
  • 1034-Max current: 1A
  • 1034-Breakthrough voltage: 400V
  • 1034-Diode Type: Rectifier diode

FEATURES

  • Low forward voltage drop
  • Low leakage current
  • High forward surge capability
  • Solder dip 275 °C max. 10 s
  • Compliant to RoHS Directive 2002/95/EC and in accordance to WEEE 2002/96/EC

Step 9:

6-pin Header and 2-Pin PCB Mount Terminal Block Connector

Step 10: PCB Design

This PCB module contains both touch sensor and 5V relay, so that this module alone can be used to switch any 5V volts AC appliance just by one touch on the touch pad, after the connection with any microcontroller.

Step 11: Ordering the PCBs

Now we have got the PCB design and it’s time to order the PCB’s. For that, you just have to go to JLCPCB.com, and click on “QUOTE NOW” button.

JLCPCB are also sponsor of this project. JLCPCB (ShenzhenJLC Electronics Co., Ltd.), is the largest PCB prototype enterprise in Chinaand a high-tech manufacturer specializing in quick PCB prototype and small-batch PCB production. You can order a minimum of 5 PCBs for just $2.

Step 12: Add Your Gerber File

To get the PCB manufactured, upload the gerber file you downloaded in the last step. Upload the.zip file or you can also drag and drop the gerber files.

Step 13:

After uploading the zip file, you’ll see a success message at the bottom if the file is successfully uploaded.You can review the PCB in the Gerber viewer to make sure everything is good. You can view both top and bottom of the PCB.

After making sure our PCB looks good, we can now place the order at a reasonable price. You can order 5 PCBs for just $2 but if it’s your first order then you can get 10 PCBs for $2.

To place the order, click on “SAVE TO CART” button.

My PCBs took 2 days to get manufactured and arrived within a week using DHL delivery option. PCBs were well packed and the quality was really good.