AN76000 CY8CMBR2110 CapSense® Design Guide.pdf

AN76000 - CY8CMBR2110
CapSense® Design Guide
Doc. No. 001-76000 Rev. *E
Cypress Semiconductor
198 Champion Court
San Jose, CA 95134-1709
Phone (USA): 800.858.1810
Phone (Intl): 408.943.2600
www.cypress.com
Copyrights
Copyrights
© Cypress Semiconductor Corporation, 2012-2016. The information contained herein is subject to change without
notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any circuitry other than circuitry
embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress
products are not warranted nor intended to be used for medical, life support, life saving, critical control or safety
applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not
authorize its products for use as critical components in life-support systems where a malfunction or failure may
reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support
systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress
against all charges.
Trademarks
PSoC Designer™, Programmable System-on-Chip™, and SmartSense™ are trademarks and PSoC® and
CapSense® are registered trademarks of Cypress Semiconductor Corp. All other trademarks or registered
trademarks referenced herein are property of the respective corporations.
Source Code
Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is
protected by and subject to worldwide patent protection (United States and foreign), United States copyright laws and
international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license
to copy, use, modify, create derivative works of, and compile the Cypress Source Code and derivative works for the
sole purpose of creating custom software and or firmware in support of licensee product to be used only in
conjunction with a Cypress integrated circuit as specified in the applicable agreement. Any reproduction, modification,
translation, compilation, or representation of this Source Code except as specified above is prohibited without the
express written permission of Cypress.
Disclaimer
CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials
described herein. Cypress does not assume any liability arising out of the application or use of any product or circuit
described herein. Cypress does not authorize its products for use as critical components in life-support systems
where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of
Cypress’ product in a life-support systems application implies that the manufacturer assumes all risk of such use and
in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
AN76000 - CY8CMBR2110 CapSense® Design GuideDoc. No. 001-76000 Rev. *E
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Contents
1.
Introduction............................................................................................................................................................ 6
1.1
1.2
1.3
1.4
1.5
2.
CapSense Technology .......................................................................................................................................... 11
2.1
2.2
2.3
3.
Abstract ......................................................................................................................................................... 6
Cypress’s CapSense Documentation Ecosystem .......................................................................................... 6
CY8CMBR2110 CapSense Express Device Features .................................................................................. 8
Document Conventions ................................................................................................................................. 10
Acronyms....................................................................................................................................................... 10
CapSense Fundamentals .............................................................................................................................. 11
Capacitive Sensing Method ........................................................................................................................... 12
2.2.1 CapSense Sigma-Delta (CSD) ......................................................................................................... 12
SmartSense Auto-Tuning .............................................................................................................................. 14
2.3.1 Process Variation.............................................................................................................................. 14
2.3.2 Reduced Design Cycle Time ............................................................................................................ 14
CapSense Schematic Design ............................................................................................................................... 16
3.1
3.2
3.3
CapSense Controller Pins ............................................................................................................................. 16
3.1.1 CapSense Buttons (CSx) .................................................................................................................. 16
3.1.2 General-Purpose Outputs (GPOx) .................................................................................................... 16
3.1.3 Modulating Capacitor (CMOD) ......................................................................................................... 17
3.1.4 Buzzer Signal Outputs (BuzzerOut0, BuzzerOut1) ........................................................................... 17
3.1.5 Host-Controlled GPOs (HostControlGPO0, HostControlGPO1) ....................................................... 19
3.1.6 Attention/Sleep ................................................................................................................................. 19
CapSense Controller Configuration ............................................................................................................... 21
3.2.1 Button Auto Reset (ARST) ................................................................................................................ 21
3.2.2 Noise Immunity ................................................................................................................................. 21
3.2.3 Automatic Threshold ......................................................................................................................... 21
3.2.4 Toggle ON/OFF ................................................................................................................................ 22
3.2.5 Flanking Sensor Suppression (FSS)................................................................................................. 22
3.2.6 LED ON Time ................................................................................................................................... 23
3.2.7 LED Effect Parameters ..................................................................................................................... 23
3.2.8 Latch Status Read ............................................................................................................................ 28
3.2.9 Analog Voltage Support .................................................................................................................... 29
3.2.10 Sensitivity Control ............................................................................................................................. 30
3.2.11 Debounce Control ............................................................................................................................. 30
3.2.12 System Diagnostics .......................................................................................................................... 31
3.2.13 Button Scan Rate.............................................................................................................................. 32
3.2.14 I2C Communication ........................................................................................................................... 33
Design Toolbox.............................................................................................................................................. 34
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Contents
3.4
3.5
4.
Electrical and Mechanical Design Considerations ............................................................................................. 49
4.1
4.2
4.3
4.4
5.
5.3
System Design Recommendations................................................................................................................ 52
Calculating Average Power ........................................................................................................................... 52
5.2.1 Button Scan Rate (TR) ...................................................................................................................... 53
5.2.2 Scan Time (TS) ................................................................................................................................. 54
5.2.3 Average Current in NO TOUCH State (IAVE_NT)................................................................................. 55
5.2.4 Average Current in TOUCH State (IAVE_T)......................................................................................... 55
5.2.5 Percentage of Active Time (P) .......................................................................................................... 55
5.2.6 Average Use Current (IAVE_U) ............................................................................................................ 55
5.2.7 Average Current (IAVE) ...................................................................................................................... 56
5.2.8 Average Power (PAVE)....................................................................................................................... 56
5.2.9 Example Calculation ......................................................................................................................... 56
Sleep Modes.................................................................................................................................................. 57
5.3.1 Low-Power Sleep Mode .................................................................................................................... 57
5.3.2 Deep Sleep Mode ............................................................................................................................. 58
Resources .............................................................................................................................................................. 59
6.1
6.2
6.3
6.4
6.5
7.
Overlay Selection .......................................................................................................................................... 49
ESD Protection .............................................................................................................................................. 50
4.2.1 Prevent ............................................................................................................................................. 50
4.2.2 Redirect ............................................................................................................................................ 50
4.2.3 Clamp ............................................................................................................................................... 50
Electromagnetic Compatibility (EMC) Considerations ................................................................................... 51
4.3.1 Radiated Interference ....................................................................................................................... 51
4.3.2 Conducted Immunity and Emissions................................................................................................. 51
PCB Layout Guidelines ................................................................................................................................. 51
Low-Power Design Considerations ..................................................................................................................... 52
5.1
5.2
6.
3.3.1 General Layout Guidelines ............................................................................................................... 34
3.3.2 Layout Estimator ............................................................................................................................... 35
3.3.3 CP, Power Consumption and Response Time Calculator ................................................................. 36
3.3.4 Design Validation .............................................................................................................................. 38
Configuring the CY8CMBR2110 .................................................................................................................... 39
3.4.1 EZ-Click Customizer Tool ................................................................................................................. 41
3.4.2 Configuring the Device using a Host Processor ............................................................................... 42
3.4.3 Third-party Programmer ................................................................................................................... 48
CY8CMBR2110 Reset ................................................................................................................................... 48
3.5.1 Hardware Reset ................................................................................................................................ 48
3.5.2 Software Reset ................................................................................................................................. 48
Website ......................................................................................................................................................... 59
Datasheet ...................................................................................................................................................... 59
Design Toolbox.............................................................................................................................................. 59
EZ-Click™ Customizer Tool .......................................................................................................................... 59
Design Support .............................................................................................................................................. 59
Appendix ................................................................................................................................................................ 60
7.1
Schematic Example ....................................................................................................................................... 60
7.1.1 Schematic 1: Ten Buttons with Ten GPOs ....................................................................................... 60
7.1.2 Schematic 2: Eight Buttons with Analog Voltage Output .................................................................. 62
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Contents
7.2
APIs for CY8CMBR2110 Configuration ......................................................................................................... 64
7.2.1 High-Level APIs ................................................................................................................................ 64
7.2.2 Low-Level APIs ................................................................................................................................. 81
Glossary.......................................................................................................................................................................... 82
Revision History ............................................................................................................................................................. 88
Document Revision History ..................................................................................................................................... 88
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1. Introduction
1.1 Abstract
This document describes how to implement capacitive sensing functionality using Cypress’s CapSense® Express
CY8CMBR2110 device. The following topics are covered in this guide:
 Features of the CY8CMBR2110
 CapSense principles of operation
 Configuration options of the CY8CMBR2110 device
 Using the Design Toolbox with the CY8CMBR2110
 System electrical and mechanical design considerations for the CY8CMBR2110
 Low-power design considerations for the CY8CMBR2110
 Additional resources and support for designing CapSense into your system
1.2 Cypress’s CapSense Documentation Ecosystem
Figure 1-1 and Table 1-1 summarize the CapSense documentation ecosystem. These resources allow the
implementers to quickly access the information they need to complete a CapSense product design. Figure 1-1 shows
a typical product design cycle with capacitive sensing; this document covers the topics highlighted in green. Table 1-1
offers links to supporting documents for each of the numbered tasks in Figure 1-1.
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Introduction
Figure 1-1. Typical CapSense Product Design Flow
1. Understand CapSense technology
= Topics covered in this document
2. Specify system requirements and
characteristics
*
†
= Applicable to MBR family of devices only
= Applicable to programmable devices only
3. Select CapSense device based on
required functionality
Design for CapSense
4. Mechanical
Design
5. Schematic
capture and
PCB layout
6. PSoC Designer project
creation†
7. Firmware
development†
8. CapSense tuning†
10. CapSense
Configuration*
†
9. Programming PSoC
11. Preproduction build (prototype)
12. Test and evaluate system functionality and
CapSense performance
Meets
specifications?
No
Yes
13. Production
Table 1-1. Cypress Documents That Support Numbered Design Tasks of Figure 1-1
Numbered Design Task of
Figure 1-1
Supporting Cypress CapSense Documentation
1
Getting Started with CapSense
2
CY8CMBR2110 Device Datasheet
3
Getting Started with CapSense
4
This document
5
This document
6
Not applicable for CY8CMBR2110
7
Not applicable for CY8CMBR2110
8
Not applicable for CY8CMBR2110
9
Not applicable for CY8CMBR2110
10
This document
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Introduction
1.3 CY8CMBR2110 CapSense Express Device Features
Cypress’s low-power CapSense controller can easily add capacitive touch sensing to your user interface. The
device’s features include:
 Register configurable CapSense Controller

Does not require firmware or device programming

Ten button solution configurable through I2C protocol

Ten general purpose outputs (GPOs)

GPOs are linked to CapSense buttons

GPOs support direct LED drive
 SmartSense™ Auto-Tuning

CapSense algorithm that continuously compensates for system, manufacturing, and environmental changes

Dynamically sets CapSense parameters

Eliminates the need for manual system tuning

Wide parasitic capcitiance(CP) range (5-40 pF)
 Advanced features

Flanking Sensor Suppression (FSS)
o

Distinguishes between signals from closely spaced buttons
User-configurable LED effects
o
On system power-on
o
On button touch
o
LED ON Time after button release
o
Standby mode LED Brightness

Buzzer signal output

Analog voltage output
o
Using external resistor bridge

Attention line interrupt to host to indicate any CapSense button status change

CapSense performance data through I2C interface
o
Simplifies production line testing and system debug
 Noise immunity

Specifically designed for superior noise immunity to external radiated and conducted noise

Low radiated noise emission
 System diagnostics

Button shorts

Improper value of modulating capacitor (CMOD)

Parasitic capacitance (CP) value out of range
 EZ-Click™ Customizer Tool

Simple graphical configuration

Dynamically configures all features

Configurations can be saved and reused later
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8
Introduction
 I2C interface

No clock stretching

Supports up to 100-kHz speed
 Wide operating voltage range

1.71—5.5 V

Ideal for both regulated and unregulated battery applications
 Low power consumption

Average current consumption of 23 µA[1] per button

Deep sleep current: 100 nA
 Industrial temperature range: –40 °C to +85 °C
 32-pin QFN package (5 mm x 5 mm x 0.6 mm)
1
Four buttons used, 180 button touches per hour, average button touch time = 1000 ms, buzzer disabled, Button Touch LED
Effects disabled, 10 pF < (CP of all buttons) < 20 pF, Button Scan Rate = 541 ms, power consumption optimized, Noise Immunity
level "Normal", CSx sensitivity "Medium".
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9
Introduction
1.4 Document Conventions
Convention
Usage
Courier New
Displays file locations, user-entered text, and source code:
C:\ ...cd\icc\
Italics
Displays file names and reference documentation:
Read about the sourcefile.hex file in the PSoC Designer User Guide.
[Bracketed, Bold]
Displays keyboard commands in procedures:
[Enter] or [Ctrl] [C]
File > Open
Represents menu paths:
File > Open > New Project
Bold
Displays commands, menu paths, and icon names in procedures:
Click the File icon and then click Open.
Times New Roman
Displays an equation:
2+2=4
Text in gray boxes
Describes Cautions or unique functionality of the product.
1.5 Acronyms
Acronym
Description
AC
Alternating current
ARST
Auto Reset
CF
Finger capacitance
CP
Parasitic capacitance
CS
CapSense
CSD
CapSense Sigma Delta
EMC
Electromagnetic Compatibility
ESD
Electrostatic Discharge
FSS
Flanking Sensor Suppression
GPO
General-Purpose Output
MSB
Most significant bit
LCD
Liquid Crystal Display
LED
Light-Emitting Diode
LSB
Least significant bit
PCB
Printed Circuit Board
POR
Power on Reset
POST
Power on Self-Test
RF
Radio Frequency
SNR
Signal to Noise Ratio
SMPS
Switched Mode Power Supply
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2. CapSense Technology
2.1 CapSense Fundamentals
CapSense is a touch sensing technology that works by measuring the capacitance of each sensor input pin on the
CapSense controller. The total capacitance on each of the sensor pins can be modeled as equivalent lumped
capacitors with values of CX,1 through CX,n as shown in Figure 2-1. Circuitry internal to the CY8CMBR2110 device
converts the magnitude of each CX into a digital code that is stored for post-processing. A modulating capacitor,
CMOD, is used by the CapSense controller’s internal circuitry. CMOD will be discussed in more detail in Capacitive
Sensing Method.
Figure 2-1. CapSense Implementation in a CY8CMBR2110 Device
CY8CMBR2110
Sensor
Capacitors
CMOD
CX,1
CX,2
CX,n
Each sensor input pin is connected to a sensor pad by traces, vias, or both, as necessary. A nonconductive overlay is
required to cover each sensor pad and constitutes the product’s touch interface. When a finger comes into contact
with the overlay, the conductivity and mass of the body effectively introduces a grounded conductive plane parallel to
the sensor pad. This action is represented in Figure 2-2. This arrangement constitutes a parallel plate capacitor,
whose capacitance is given by the following equation:
 =
0  

Equation 1
Where:
CF = The capacitance affected by a finger in contact with the overlay over a sensor
ε0 = Free space permittivity
εr = Dielectric constant (relative permittivity) of overlay
A = Area of finger and sensor pad overlap
D = Overlay thickness
AN76000 - CY8CMBR2110 CapSense® Design GuideDoc. No. 001-76000 Rev. *E
11
CapSense Technology
Figure 2-2. Section of Typical CapSense PCB with the Sensor Being Activated by a Finger
In addition to the parallel plate capacitance, a finger in contact with the overlay causes electric field fringing between
itself and other conductors in the immediate vicinity. Typically, the effect of these fringing fields is minor, and it can
usually be ignored.
Even without a finger touching the overlay, the sensor input pin has some parasitic capacitance (CP). CP results from
the combination of the CapSense controller internal parasitic and electric field coupling among the sensor pad,
traces, and vias, and other conductors in the system, such as ground plane, other traces, any metal in the product’s
chassis or enclosure, and so on. The CapSense controller measures the total capacitance (C X) connected to a
sensor pin.
When a finger is not touching a sensor, use this equation:
 = 
Equation 2
With a finger on the sensor, CX equals the sum of CP and CF:
 =  + 
Equation 3
In general, CP is an order of magnitude greater than CF. CP usually ranges from 10—20 pF, but in extreme cases it
can be as high as 40 pF. CF usually ranges from 0.1—0.4 pF.
2.2 Capacitive Sensing Method
CY8CMBR2110 device supports the CapSense Sigma Delta (CSD) with SmartSense Auto-Tuning for converting
sensor capacitance (CX) into digital counts. The CSD method is described in the following sections.
2.2.1 CapSense Sigma-Delta (CSD)
The CSD method in the CY8CMBR2110 device incorporates C X into a switched capacitor circuit, as shown in Figure
2-3. CX is alternatively connected to Gnd and the AMUX bus by the non-overlapping switches Sw1 and Sw2. Sw1
and Sw2 are driven by the Precharge Clock to bleed a current, isensor from the AMUX bus. The magnitude of isensor is
directly proportional to the magnitude of CX. The sigma-delta converter samples the AMUX bus voltage and
generates a modulating bit stream that controls the constant current source, IDAC. The IDAC charges AMUX such
that the average AMUX bus voltage is maintained at Vref. The sensor bleeds off isensor from CMOD, which, in
combination with Rbus, forms a low-pass filter that attenuates precharge switching transients at the sigma-delta
converter input.
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CapSense Technology
Figure 2-3. CSD Block Diagram
CY8CMBR2110
Gnd
Precharge
Clock
IDAC
Sw1
Vref
Gnd
Sw2
Rbus
Cx
isensor
AMUX
Bus
High-Z
input
Sigma-Delta
Converter
Cmod
= External Connection
In order to maintain the AMUX bus voltage at Vref, the sigma-delta converter matches IDAC to isensor by controlling
the bit stream duty cycle. The sigma-delta converter stores the bit stream over the duration of a sensor scan, and the
accumulated result is a digital output, raw count, which is directly proportional to C X. This raw count is interpreted by
high-level algorithms to resolve the sensor state. Figure 2-4 plots the CSD raw counts from a number of consecutive
scans during which the sensor is touched and then released by a finger. As explained in CapSense Fundamentals,
the finger touch causes CX to increase by CF, which in turn causes raw counts to increase proportionally. By
comparing the shift in steady state raw count level to a predetermined threshold, the high-level algorithms can
determine whether the sensor is in an ON (Touch) or OFF (No Touch) state. To learn more about Raw Counts,
Finger Threshold, and Signal-to-Noise Ratio (SNR), refer to Getting Started with CapSense.
Figure 2-4. CSD Raw Counts During a Finger Touch
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CapSense Technology
2.3 SmartSense Auto-Tuning
Tuning the touch-sensing user interface is critical for proper system operation and a pleasant user experience.
Unfortunately, tuning is time-consuming because it is an iterative process. In a typical development cycle, the
interface is tuned in the initial design phase, during system integration, and before production ramp. SmartSense
Auto-Tuning was developed to simplify the user interface development cycle. It is a CapSense algorithm that
continuously compensates for system, manufacturing, and environmental changes. It is easy to use and reduces
design cycle time by eliminating manual tuning during the prototype and manufacturing stages. SmartSense AutoTuning tunes each CapSense button automatically at power up and maintains optimum button performance during
runtime. SmartSense Auto-Tuning adapts for manufacturing variation in PCBs and overlays and automatically tunes
out noise from sources such as LCD inverters, AC lines, and switch-mode power supplies.
2.3.1 Process Variation
The CY8CMBR2110 device’s SmartSense Auto-Tuning is designed to work with CP values in the range of 5—40 pF.
The sensitivity parameter for each button is set automatically, based on its characteristics. This parameter improves
yield in mass production because every button maintains a consistent response regardless of C P variation between
the buttons. CP can vary due to PCB layout and trace length, PCB manufacturing process variation, or vendor-tovendor PCB variation within a multi-sourced supply chain. The sensitivity of a button depends on CP; higher CP
values decrease sensitivity, resulting in decreased finger touch signal amplitude. A change in CP can result in a
button becoming too sensitive, not sensitive enough, or non-operational. When this happens, you must retune the
system and, in some cases, re-qualify the user interface subsystem. SmartSense Auto-Tuning resolves these issues.
SmartSense Auto-Tuning makes platform designs possible. For example, consider the capacitive touch sensing
multimedia keys on a laptop computer. The parasitic capacitance of the CapSense buttons can vary in different
models of the same platform design depending on the size of the laptop and the keyboard layout. In this example, a
wide-screen laptop model would have larger spaces between the buttons than a standard-screen model. Therefore, a
wide-screen model would have longer traces between each button and the CapSense controller, which would result
in higher CP values. Though the buttons’ functionality is identical for all of the laptop models, the buttons must be
tuned for each model. SmartSense Auto-Tuning lets you do platform designs using the recommended practices
shown in the PCB Layout in Getting Started with CapSense.
Figure 2-5. Design of Laptop Multimedia Keys for a 21-Inch Model
Figure 2-6. Design of Laptop Multimedia Keys for a 15-Inch Model with Identical Functionality and Button Size
2.3.2 Reduced Design Cycle Time
When you design a capacitive button interface, the most time-consuming tasks are firmware development, layout,
and button tuning. With a typical touch-sensing controller, the buttons must be retuned when the design is ported to
different models or when there are changes to the mechanical dimensions of the PCB or the button PCB layout. A
design with SmartSense Auto-Tuning meets these challenges because it does not require firmware development,
manual tuning, or retuning. In addition, SmartSense Auto-Tuning speeds up a typical design cycle. Figure 2-7
compares the design cycles of a typical touch-sensing controller and a SmartSense Auto-Tuning-based design.
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14
CapSense Technology
Figure 2-7. Typical Capacitive User Interface Design Cycle Comparison
Typical capacitive user interface Design Cycle
Feasibility
Study
Mechanical Design
Schematics
Design
Retuning for any
changes
Production Fine
Tuning
PCB Layout
Design
System
Integration
Design
Validation
Review
Firmware
Development
Tuning process
CapSense® Express with SmartSense™ Auto-Tuning based
capacitive user interface Design Cycle
Feasibility
Study
Schematics
Design
PCB Layout
Design
Review
Mechanical Design
System
Integration
Production
AN76000 - CY8CMBR2110 CapSense® Design GuideDoc. No. 001-76000 Rev. *E
Design
Validation
Device
Configuration
Production
15
3. CapSense Schematic Design
Cypress’s CY8CMBR2110 device is configured using hardware and the EZ-Click Customizer Tool via the I2C
interface. This section gives an overview of the CapSense controller pins and registers and how to configure them.
3.1 CapSense Controller Pins
26
25
28
27
CY8CMBR2110
QFN
15
16
13
14
24
23
22
21
20
19
18
17
CS 7
CS 8
CS 9
GPO 9
GPO 8
GPO 7
GPO 6
XRES
HostControlGPO1
BuzzerOut1
Atttention\Sleep
GPO 5
9
( Top View )
10
11
12
1
2
3
4
5
6
7
8
I2C SDA
BuzzerOut0
HostControlGPO0
VSS
CS 1
CS 0
GPO 0
GPO 1
GPO 2
GPO 3
GPO 4
I2C SCL
30
29
32
31
VSS
CMOD
CS 2
CS 3
VDD
CS 4
CS 5
CS 6
Figure 3-1. CY8CMBR2110 Pin Diagram
3.1.1 CapSense Buttons (CSx)
The CY8CMBR2110 controller has ten capacitive sense inputs, CS0—CS9. Each capacitive button requires a
connection to one of the capacitive sense inputs. You must ground all unused CapSense (CSx) input pins.
3.1.2 General-Purpose Outputs (GPOx)
There are ten active low outputs on the CY8CMBR2110 controller, GPO0—GPO9. Each output is driven by its
corresponding capacitive sensing input, CSx. You can use GPOs to directly drive LEDs or to replace mechanical
switches. GPOs are in strong drive[2] mode. All unused GPO pins must be floated.
2
When a pin is in strong drive mode, it is pulled up to VDD when the output is HIGH and pulled down to Ground when the output is
LOW.
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CapSense Schematic Design
3.1.3 Modulating Capacitor (CMOD)
Connect a 2.2 nF (±10%) capacitor to the CMOD pin.
3.1.4 Buzzer Signal Outputs (BuzzerOut0, BuzzerOut1)
The buzzer signal outputs are used to give audio feedback when a CapSense button is touched. This is helpful in
designs where audio sensors are used. Use piezoelectric buzzers for buzzer signal outputs.
The buzzer signal outputs are strong drive outputs. The outputs are driven commonly by all of the CSx buttons. If a
buzzer is not used, BuzzerOut0 and BuzzerOut1 can be used as Host-Controlled GPOs. Table 3-2 shows the various
buzzer settings.
The buzzer signal outputs can have two configurations:
1.
2.
AC 1-pin Buzzer: A buzzer is connected to the BuzzerOut0 pin of the device as shown in Figure 3-2. A
square wave with a specified frequency and duty cycle is driven on this pin. The BuzzerOut1 pin can be left
floating, or it can be used as a host-controlled GPO.
AC 2-pin Buzzer: A buzzer is connected to the BuzzerOut0 and BuzzerOut1 pins of the device as shown in
Figure 3-3. Two out-of-phase square waves with a specified frequency and duty cycle are driven on these
pins.
Figure 3-2. AC 1-pin Buzzer Configuration
VDD
Buzzer
BuzzerOut1
CY8CMBR2110
BuzzerOut0
Figure 3-3. AC 2-pin Buzzer Configuration
Buzzer
BuzzerOut0
CY8CMBR2110
BuzzerOut1
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CapSense Schematic Design
The buzzer signal frequency is configurable. Table 3-1 lists the various frequencies and the corresponding output
duty cycle.
Table 3-1. Buzzer Signal Output frequency and duty cycle
Buzzer Signal Output
Frequency (kHz)
Duty Cycle
1.00
50%
1.14
57.14%
1.33
50%
1.60
60%
2.00
50%
2.67
66.7%
4.00
50%
Buzzer ON time has a range of (1 to 127) x Button Scan Rate Constant. To learn more about this constant, refer
Button Scan Rate. The buzzer signal output is driven for the configured time and does not depend on the button
touch time. The output goes to the idle state after the Buzzer ON time elapses, even if the button remains touched as
shown in Figure 3-4. The idle state of the buzzer pin can be configured to either V DD or Ground. The buzzer signal
output restarts immediately if a button is touched before the Buzzer ON time elapses as shown in Figure 3-5.
When you enable Buzzer Signal Output, the Buz_Op_Duration register (in the Device Configuration mode) should
have a minimum value of 1. To learn more about this register, refer to the CY8CMBR2110 Datasheet Appendix.
Figure 3-4. Buzzer Time-out
CS0 kept touched
CS0
Buzzer ON Time
Buzzer
Output
Figure 3-5. Buzzer Signal Output Restart
CS0
Touched
CS1
Touched
CS0
CS1
Buzzer
Output
Buzzer ON Time
Buzzer output
restarted
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3.1.5 Host-Controlled GPOs (HostControlGPO0, HostControlGPO1)
The Host Controlled GPOs’ logic states can be controlled by the host. These outputs are in strong drive mode.
If a buzzer is not used in your design, the BuzzerOut0 and BuzzerOut1 pins also can be used as host-controlled
GPOs. If an AC 1-pin buzzer is used, the BuzzerOut1 pin can be used as a host-controlled GPO.
The host can control these GPOs in the Operating mode, Production Line Test mode, and Debug Data mode.
Host-Controlled GPOs are in the LOW state at power-on and have to be configured after reset. The configuration
settings cannot be saved to flash memory, unlike other feature configuration settings.
HostControlGPO1 has a positive going pulse of 16 ms during power-on. To eliminate this pulse, use an external RC
network (± 5% tolerance) on the XRES pin as shown in Figure 3-6. This keeps the device in XRES reset during every
power-on. When the device comes out of XRES reset after 16 ms, normal operation occurs.
Table 3-2. Buzzer and Host-Controlled GPOs
Buzzer
Configuration
BuzzerOut0 pin
BuzzerOut1 pin
Maximum Available Host
Controlled GPOs
No buzzer
Floating / Host-Controlled GPO3
Floating / Host-Controlled GPO2
4
AC 1-pin
Buzzer pin 0
Floating / Host-Controlled GPO2
3
AC 2-pin
Buzzer pin 0
Buzzer pin 1
2
Figure 3-6. XRES Pin Configuration to Avoid HostControlGPO1 Pulse During Power-On
1 µF
VDD
XRES
3.2 kΩ
CY8CMBR2110
3.1.6 Attention/Sleep
Attention/Sleep is a bidirectional line in Open Drain Low drive mode that can be controlled by both the host and the
device. Attention/Sleep is used to read CapSense data from the device and to enter and exit Low-Power Sleep and
Deep Sleep modes.
3.1.6.1 Read Device Data
Two steps are required for the host to read data from the device.
1.
The host pulls the Attention/Sleep line low.
2.
The host initiates I2C communication with the device.
When the Attention/Sleep line is pulled high, the device is in Low-Power Sleep or Deep Sleep mode (if the Deep
Sleep bit in Host_Mode register is set). The device can NACK I2C communication at this time. Keep the
Attention/Sleep line pulled HIGH to conserve power.
To read the device data, the host can pull the Attention/Sleep line low at any time. When the Attention/Sleep line is
low, the device can NACK I2C communication, but very infrequently.
If any CapSense button is touched, the device pulls the Attention/Sleep line low to interrupt the host, as shown in
Figure 3-7. The host then can read the CapSense data using I2C communication with the device. If more than one
button is touched simultaneously, the Attention/Sleep line is pulled low for the duration, as shown in Figure 3-8. The
Attention/Sleep line goes high when the button is released.
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CapSense Schematic Design
The host should have both a falling edge and a rising edge triggered interrupt for the Attention/Sleep line, so it can
recognize both a button touch and a button release. If a rising edge triggered interrupt is not available, the host
should continuously poll the button status after the Attention/Sleep line goes low. Polling should be done at the Button
Scan Rate constant.
Figure 3-7. Attention/Sleep Line Status with CS0 and CS1 Touched Separately
Touch
CS1
Release
CS1
Touch
CS0
Release
CS0
CS0
CS1
Attention/Sleep
Line
Figure 3-8. Attention/Sleep Line Status with CS0 and CS1 Touched Simultaneously
Touch
CS0
Touch Release
CS1
CS1
Release
CS0
CS0
CS1
Attention/Sleep
Line
3.1.6.2 Sleep Modes
There are two possible sleep mode configurations
1.
Pull the Attention/Sleep line to VDD to enable Low Power Sleep Mode.
2.
Pull the Attention/Sleep line to VDD and set the Deep Sleep bit in Host_Mode register (in Operating Mode) to
enable Deep Sleep Mode.
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CapSense Schematic Design
3.2 CapSense Controller Configuration
3.2.1 Button Auto Reset (ARST)
Button Auto Reset determines the maximum time a button is considered to be ON when CSx is continuously touched.
The button is turned OFF after the ARST period. This feature prevents a button from getting stuck if a metal object is
placed too close to it. The ARST period can be configured to either 5 seconds or 20 seconds. The Button Auto Reset
is shown in Figure 3-9.
Figure 3-9. Button Auto Reset
Button is touched for more
than the Auto Reset period
Auto Reset period
CS0
GPO0
GPO0 not driven as CS0
is considered to be OFF
After the CSx is turned off because of Button Auto Reset and after the button is released, do not touch the button for
a time equal to the Button Scan Rate.
3.2.2 Noise Immunity
This setting determines the device’s immunity to external radiated and conducted noise such as audio frequency
noise from power amplifiers, radio frequency noise from wireless transmitters, ESD, and power line surges.
In a system without major noise concerns, select “Normal” Noise Immunity. For a system in a high-noise
environment, select “High” Noise Immunity. Power consumption and response time increase when Noise Immunity is
“High”. If you require the same response time with “High” Noise Immunity, reduce the button debounce value. For
more information, refer to Debounce Control.
3.2.3 Automatic Threshold
As explained in CapSense Sigma-Delta (CSD), the sensor ON or OFF state is determined by comparing the shift in
raw counts to a predetermined threshold, called the Finger Threshold. Finger Threshold is configurable and decides
the other thresholds for the device. To learn more about the Finger Threshold, refer to Getting Started with
CapSense.
You can configure the Finger Threshold for each button individually or use the Automatic Threshold feature. The
Automatic Threshold sets the various thresholds dynamically for each button, depending on the noise in the
environment. For a variable noise environment, use Automatic Threshold. If you need to manually adjust the finger
threshold, disable Automatic Threshold and set the finger threshold to the desired level.
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CapSense Schematic Design
3.2.4 Toggle ON/OFF
When Toggle ON/OFF is enabled, the state of GPOx changes on every rising edge of CSx. Toggle ON/OFF
configuration is shown in Figure 3-10.
You can enable the toggle ON/OFF feature on each CapSense button individually.
Figure 3-10. Example of Toggle ON/OFF Feature
CS0
GPO0
3.2.5 Flanking Sensor Suppression (FSS)
FSS distinguishes between signals from closely spaced buttons, eliminating false touches. It ensures that the system
recognizes only the first button touched. FSS allows only one CSx to be in the TOUCH state at a time. If a finger
contacts multiple CSx buttons, only the first one to sense a TOUCH state will turn ON.
FSS also is useful when nearby buttons can produce opposite effects such as an interface with two buttons for
brightness control (UP or DOWN).
FSS can be enabled for each button individually. FSS configuration is shown in Figure 3-11 and Figure 3-12.
In applications such as washing machine panels, buttons can be separated into two groups: one with FSS enabled
and one with FSS disabled. This allows you to distinguish between closely spaced buttons at one end of the design,
while accommodating multi-touch functionality at the other end.
Figure 3-11. FSS When Only One Button is Touched
CS0
CS1
CS2
CS3
No button is ON prior to the touch
CS0
CS1
CS2
CS3
CS1 is reported as ON upon touch
Figure 3-12. FSS When Multiple Buttons are Touched With One Button ON Previously
CS1 is touched; reported ON
CS2 is also touched along with CS1;
only CS1 is reported ON
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CapSense Schematic Design
3.2.6 LED ON Time
LED ON Time specifies the duration for which GPOx is driven low after CSx is released as shown in Figure 3-13.
LED ON Time can range from 0—5100 ms, with a resolution of 20 ms.
Figure 3-13. LED ON Time
CS0
GPO0
LED ON Time
LED ON Time varies from device to device. Accuracy is ±10% at a range of -40 °C to +85 °C.
If a Button Auto Reset (ARST) is triggered for CSx, LED ON Time is not applied on GPOx. LED ON Time is disabled
if Toggle ON/OFF is enabled.
LED ON Time applies only to one GPOx at a time, meaning the LED ON Time counter resets every time a CSx
transitions to a NO TOUCH state. Figure 3-14 illustrates how LED ON Time operates when multiple buttons are
touched. CS1 resets the LED ON Time counter, causing GPO0 to turn OFF prematurely.
Figure 3-14. LED ON Timing for Multiple Buttons
CS0
CS1
GPO0
GPO1
Start LED ON Time
Counter
LED ON Time
Reset LED ON
Time Counter
Restart LED ON
Time Counter
3.2.7 LED Effect Parameters
Power-On LED Effects and Button Touch LED Effects use the following parameters:
 Low-brightness: Minimum LED intensity
 Low-brightness time: The time period the LED remains in a low-brightness state
 Ramp-up time: The time period the LED transitions from low-brightness to high-brightness
 High-brightness: Maximum LED intensity
 High-brightness time: The time period the LED remains in a high-brightness state
 Ramp-down time: The time period the LED transitions from high-brightness to low-brightness
 Repeat rate: The number of times the effects are repeated
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CapSense Schematic Design
GPOs are configured in groups to have the same parameters. The different groups are:
 {GPO1, GPO2, GPO3}
 {GPO4, GPO5, GPO6}
 {GPO7, GPO8, GPO9}
GPO0’s parameters can be configured separately. This functionality is useful in designs where the CS0 button has a
special function such as the power button.
The brightness levels can range from 0—100%. The time range is 0—1600 ms. High-brightness should be kept
higher than low-brightness.
3.2.7.1 Power-On LED Effects
If this feature is enabled, all LEDs connected to GPOs show dimming and fading effects for an initial time, at system
power-on. You can configure these effects and the effect time. During this time, all CapSense buttons are disabled.
The device responds to any button touch only after the effects are complete.
The effects are seen after the device initialization time from power-on. This time is less than 350 ms if Noise Immunity
is “Normal” and less than 1000 ms if Noise Immunity is “High”.
After power-on, system diagnostics, including a power-on self-test, are performed. If any CapSense button fails, the
effects are not seen on the corresponding GPO. To learn more about this test, see System Diagnostics.
During Power-On LED Effects, the device ACKs I2C communication, but all write commands are ignored. The host
can only read Operating Mode data.
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CapSense Schematic Design
Power-On LED Effects can be configured to occur concurrently or sequentially on all the GPOs as shown in
Figure 3-15 and Figure 3-16.
Figure 3-15. Example Power-On LED Effects (Concurrent)[3]
Effects
completed
Power on
90%
Ra
m
pU
p
Ra
m
pU
p
wn
10%
Do
n
ow
0%
Normal
Operation
p
m
Ra
pD
m
Ra
GPOx LED
Brightness
90%
10%
10%
<= (350 ms/ 500
ms
1000 ms)
200
ms
500
ms
200
ms
500
ms
200
ms
500
ms
0%
200
ms
<= (3150 ms / 3800 ms)
Figure 3-16. Example Power-On LED Effects (Sequential) with Two-Button Design[4]
Effects
completed
Power on
10%
10%
0%
0%
100
ms
100%
n
ow
Ra
mp
Up
300 100 300
ms ms ms
D
mp
Ra
<= 350ms/
1000 ms
GPO1 LED
Brightness
Normal
Operation
n
ow
GPO0 LED
Brightness
D
mp
Ra
Ra
mp
Up
100%
10%
10%
0%
0%
300 100 300
ms ms ms
100
ms
<= 1950 ms / 2600 ms
3
4
Ramp up time = 500 ms; High-brightness = 90%; High-brightness time = 200 ms; Ramp down time = 500 ms;
Low-brightness = 10%; Low-brightness time = 200 ms; Repeat rate = 1
Ramp up time = 300 ms; High-brightness = 100%; High-brightness time = 100 ms; Ramp down time = 300 ms;
Low-brightness = 10%; Low-brightness time = 100 ms; Repeat rate = 0
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CapSense Schematic Design
3.2.7.2 Button Touch LED Effects
When this feature is enabled if a button is touched, the associated LEDs connected to GPOs show dimming and
fading effects. You can configure these effects and the effect time.
Button-Controlled LED Effects can be breathing effect enabled or disabled. Both are shown in Figure 3-17.
Breathing Effect Enabled: With the breathing effect enabled, LED intensity changes from Standby Mode LED
Brightness to low-brightness immediately when a button is touched. The LED then ramps up to high-brightness and
stays at that level for high-brightness time. The LED then ramps down to low-brightness and stays at that level for
low-brightness time. This effect repeats as long as the button is touched. When the button is released, the breathing
effect cycle continues until it is complete. The breathing effects cycle may repeat depending on the repeat rate.
Breathing Effect Disabled: With the breathing effect disabled, the LED intensity changes from Standby Mode LED
Brightness to low-brightness immediately when a button is touched. The LED then ramps up to high-brightness and
stays at that level as long as the button is touched. When the button is released, the LED maintains high-brightness
for high-brightness time then ramps down to low-brightness and stays at that level for low-brightness time. This effect
may repeat depending on the repeat rate.
If the Button Touch LED Effects are ongoing on a GPOx and the corresponding CSx is touched again, then the
pattern restarts on GPOx.
If the Toggle ON/OFF feature is enabled, the LEDs toggle between Standby Mode LED Brightness and highbrightness on successive button touches as shown in Figure 3-18.
When Button Touch LED Effects are enabled, the LED ON Time is automatically disabled. When the device goes into
Deep Sleep, ongoing Button Touch LED Effects are immediately disabled.
Figure 3-17. Button Touch LED Effects[5]
Button
Touched
Button
Released
Button
High
Brightness
n
ow
Ra
mp
Up
D
mp
Ra
Intensity with
Breathing effect
enabled
Low Brightness
TRU
TH
TRD
TL
n
ow
Ra
mp
Up
High Hold
Time
D
mp
Ra
High Brightness
Intensity with
Breathing effect
disabled
Repeats for N times as specified by Repeat Rate
Low Brightness
Repeats for N times as specified by Repeat Rate
TRU
5
TH TRD
TL
TRU = Ramp Up Time
TRD = Ramp Down Time
TH = High-Brightness
TL = Low-Brightness
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CapSense Schematic Design
Figure 3-18. Button Touch LED Effects with Toggle ON/OFF Enabled
Button
Released
Button
Touched
Button
Touched
Button
Released
Button
Ra
mp
Up
n
ow
Intensity
D
mp
Ra
High Brightness
Standby Mode
LED Brightness
Standby Mode
LED Brightness
TRD
TRU
3.2.7.3 Last Button LED Effect
You can configure Button Touch LED Effects to be interrupted on one GPO if any other button in touched. The effects
reset on the first GPO and start on the GPO associated with the last button touched as shown in Figure 3-19. This
feature is disabled by default.
If Toggle ON/OFF is also enabled for some buttons, the Last Button LED Effect is disabled for those buttons. If
Flanking Sensor Suppression (FSS) is enabled, and two buttons are touched simultaneously, Last Button LED Effect
does not apply, as the second button touched does not turn ON.
Figure 3-19. Button Touch LED Effects (Breathing Enabled) with Last Button LED Effect Enabled
CS0
Touched
CS1
Touched
CS0
Released
CS1
Released
CS0
CS1
pD
Ram
n
ow
GPO0 LED
Brightness
Ram
pU
p
High
Brightness
Low Brightness
TRU
TH TRD
TL
pD
Ram
n
ow
GPO1 LED
Brightness
Ram
pU
p
High
Brightness
Low Brightness
TRU
TH TRD
TL
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Repeats for N times as
specified by Repeat Rate
27
CapSense Schematic Design
3.2.7.4 Standby Mode LED Brightness
When the CapSense button CSx is OFF, you can configure the LED associated with the corresponding GPOx to
have a Standby Mode LED Brightness for LED backlighting. This configuration improves the look-and-feel of the
design.
Standby Mode LED Brightness can be configured to be 0%, 20%, 30%, or 50%. Standby Mode LED Brightness
should be the same as low-brightness.
The LEDs associated with GPOx remain on Standby Mode LED Brightness after the conclusion of Power-On LED
Effects or Button Touch LED Effects, when the CSx is OFF.
Standby Mode LED Brightness increases the power consumption of the device because the device does not go into
Low-Power Sleep mode. When the device goes into Deep Sleep mode, Standby Mode LED Brightness is disabled.
3.2.8 Latch Status Read
When a CapSense button CSx is touched, the device generates an interrupt to the host by pulling the Attention/Sleep
line low. Then, the host processor can read the device Register Map through I2C communication to learn the
CapSense button status. To learn more refer to Attention/Sleep. To learn more about I2C communication, refer to the
CY8CMBR2110 Datasheet.
When the device interrupts the host, the host may not be able to service the interrupt immediately. As a result, the
host could miss the button touch. To avoid missing any button touches, the host needs to read both the button status
(CS) and the latch status (LS) for the proper information about any button touch. CS is stored in
Button_Current_Stat0 and Button_Current_Stat1 registers in Operating Mode. LS is stored in Button_Latch_Stat0
and Button_Latch_Stat1 registers in Operating Mode. For register map details, refer to the CY8CMBR2110
Datasheet Appendix.
The Button Status bit is set on a button touch and cleared on button release. The Latch Status bit is set on a button
touch. This bit is automatically cleared when the host reads the Button status.
Table 3-3 lists the various cases for a button touch and its acknowledgment. These cases are shown in Figure 3-20
and Figure 3-21.
Table 3-3. Latch Status Read
Button Status
(CS)
Latch Status
(LS)
0
0
CSx is not touched during the current I2C read
Host has already acknowledged any previous CSx touch in the last I2C read
0
1
CSx was touched before the current I2C read
This CSx touch was missed by the host
1
0
CSx was touched and acknowledged by the host during the previous I 2C read
This CSx is still touched during current I2C read
1
1
CSx is touched during the current I2C read
Interpretation
Figure 3-20. Latch Status Read Case 1
CS = 0
LS = 0
CS = 0
LS = 1
Button
Status
Latch
Status
I2C Read
I2C Read
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CapSense Schematic Design
Figure 3-21. Latch Status Read Case 2
CS = 0
LS = 0
CS = 1
LS = 1
CS = 1
LS = 0
I2C Read
I2C Read
I2C Read
Button
Status
Latch
Status
3.2.9 Analog Voltage Support
A general external resistive network with a host processor, such as the one shown in Figure 3-22, can configure the
host to perform different functions based on the voltage level seen at the input pin. You can vary this voltage level
using a combination of resistors and switches between VDD and ground.
Figure 3-22. A General External Resistive Network
VDD
R1
Key 1
R4
R3
R2
Host Processor
VDD
Key 2
R5
R8
R7
R6
The analog voltage support feature of CY8CMBR2110 gives you the option to control these switches using
CapSense buttons. Each switch can be replaced with one GPOx. When a CSx button is touched, the corresponding
GPOx goes low; therefore, the switch is closed (shorted to ground). When the button is released, the corresponding
switch is left open. This is shown in Figure 3-23.
If this feature is enabled, the GPOs cannot be used simultaneously in the external resistive network and for the LED
drive. If only one button needs to be ON for analog voltage support, enable FSS with this feature. Usually, the GPO
pins are in strong drive mode, however, when this feature is enabled, the GPOs are in Open Drain Low drive mode.
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CapSense Schematic Design
Figure 3-23. Analog Voltage Support from CY8CMBR2110
VDD
R1
Key 1
R4
GPO4
R2
R3
GPO3
GPO2
GPO1
VDD
Host Processor
Key 2
R5
R8
GPO8
R7
GPO7
R6
GPO6
GPO5
3.2.10 Sensitivity Control
The sensitivity of each CapSense button can be set individually. Sensitivity determines the minimum CF required to
turn ON a button. The following factors affect the button’s sensitivity:
1. Overlay thickness: The thicker the overlay, the higher the sensitivity requirement.
2. System noise: As system noise increases, sensitivity needs to be lower, to avoid false button triggers.
3. Form factor of the design: A relatively large button size is required to support a low sensitivity (Higher C F).
For small-button diameters, the sensitivity needs to be high.
4. Power Consumption: Power consumption increases for high sensitivity buttons. For low power consumption
needs, the sensitivity needs to be low.
The different sensitivity settings available are “High”, “Medium”, and “Low”.
3.2.11 Debounce Control
The Debounce feature avoids false button triggering from noise spikes or system glitches, by specifying the minimum
time a button has to be touched for a valid touch input.
The debounce time can vary depending on the button’s function. For example, the power button should have a long
debounce time to avoid inadvertently switching the system ON/OFF. Shorter debounce times speed up the device’s
response to a button touch.
The debounce value for the CS0 button can be set separately from the CS1—CS9 buttons. This functionality is useful
in designs where the CS0 button has a special function such as the power button. The debounce can range from 1—
255.
The device’s Response Time depends on the button debounce. Table 3-4 lists some examples of device Response
Time for different debounce values6.To calculate the Response Time for any debounce value, refer to Response
Time.
Table 3-4. Example Response Times for Debounce Values
Debounce Value
6
Response Time for Consecutive
Button Touch (ms)
1
70
4
105
7
140
10
175
100
1225
200
2380
255
3010
8-buttons, Noise Immunity level "Normal", Response Time optimized design
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CapSense Schematic Design
3.2.12 System Diagnostics
A built-in power-on self-test (POST) mechanism performs five tests at power-on reset (POR), which can be useful in
production testing. If any button fails, a 5-ms pulse is sent out on the corresponding GPO within 350 ms if Noise
Immunity is “Normal” and 1000 ms if Noise Immunity is “High”.
Figure 3-24. Example Showing CS0, CS1 Passing the POST and CS2, CS3 Failing
GPO0
(High)
GPO1
(High)
GPO2
5ms pulse
GPO3
5ms pulse
To find out the result of the System Diagnostics, use the EZ-Click Customizer Tool. To learn more about the tool,
refer to the EZ-Click Customizer Tool User Guide.
If you need to read the entire device’s data, you can change the device’s Register Map mode to “Production Line
Test” mode and read the data through the I2C lines. To learn more about changing Register Map modes, refer to the
CY8CMBR2110 Datasheet Register Map Modes. To learn more about device data, refer to I2C Communication.
Because you can read the GPOs’ status using I2C, you do not need to create an interface between the GPOs and the
host controller pins.
The following tests are performed on all of the buttons.
3.2.12.1 Button Shorted to Ground
If any button is found to be shorted to ground, it is disabled.
Figure 3-25. Button Shorted to Ground
Button
CY8CMBR2110
shorting
3.2.12.2 Button Shorted to VDD
If any button is found to be shorted to VDD, it is disabled.
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CapSense Schematic Design
Figure 3-26. Button Shorted to VDD
VDD
shorting
Button
CY8CMBR2110
3.2.12.3 Button-to-Button Short
If two or more buttons are found to be shorted to each other, all of these buttons are disabled.
Figure 3-27. Button-to-Button Short
Button
shorting
CY8CMBR2110
Button
3.2.12.4 Improper Value of CMOD
Recommended value of CMOD is 2.2 nF, ±10%.
If the value of CMOD is found to be less than 1 nF or greater than 4 nF, all of the buttons are disabled.
3.2.12.5 Button CP > 40 pF
If any button’s CP is greater than 40 pF, that button is disabled.
3.2.13 Button Scan Rate
The button scan rate specifies the time between successive button scans by the device. Use the following equation to
calculate the rate:
Button Scan Rate = Button Scan Rate constant + Button Scan Rate offset
Equation 4
The Button Scan Rate is configurable from 25—561 ms.
The Button Scan Rate constant depends on the number of buttons and the Noise Immunity level selected. For a
higher number of buttons, the constant is higher. Similarly, for “High” Noise Immunity, the constant is higher.
If you use a maximum of five buttons, the Button Scan Rate constant depends on how you optimize your design:
Response Time Optimization: The time between consecutive button scans is shorter. As more scans occur in a
fixed time, the device responds more quickly to a button touch. However, power consumption increases.
Power Consumption Optimization: The time between consecutive button scans is longer. As fewer scans occur in
a fixed time, the device takes longer to respond to a button touch. As a result, power consumption decreases.
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You can configure the Button Scan Rate offset using the EZ-Click Customizer Tool. The Button Scan Rate constant is
given in Table 3-5.
Table 3-5. Button Scan Rate Constant
Button Scan Rate Constant
Button Count
Response Time-Optimization
Power Consumption Optimization
Noise Immunity
“Normal”
Noise Immunity
“High”
Noise Immunity
“Normal”
Noise Immunity
“High”
≤5
25
35
35
55
>5
35
55
35
55
As an example, consider a design with four buttons and the following parameters:
 CP between 10—20 pF for all buttons
 Sensitivity is high for all buttons
 Noise Immunity is “Normal”
 Debounce for each button is set to 10
 Average button touches per hour = 200
 Average touch time = 1000 ms
 Buzzer and Button Touch LED Effects are disabled
 Button Scan Rate offset = 0.
 The current consumption per button is:

Response Time Optimized = 0.3075 mA

Power Consumption Optimized = 0.2204 mA
The response times for first button touch as well as consecutive button touches are:

Response Time Optimized = 125 ms

Power Consumption Optimized = 175 ms
Note that the response time optimized design consumes a lot more power and responds more quickly to a button
touch when compared to the power consumption optimized design. To find the response time for your design, refer to
the Design Toolbox.
Button scan rate varies from device to device, and it is ±10% accurate at a temperature range of -40 °C to +85 °C.
3.2.14 I2C Communication
I2C is the interface used to communicate between the CY8CMBR2110 (I2C slave) and the host (I2C master).
To learn more about the protocol and the communication procedure, refer to the CY8CMBR2110 Datasheet I2C
Communication section.
For proper I2C communication between the host and the device, follow these guidelines:
 The host processor should pull the Attention/Sleep line low before initiating any I2C communication or the device
might NACK the host.
 The host processor should not initiate or continue an I2C communication with the device unless:

The host needs to configure the device.

The device interrupts the host.

The host needs to read and verify the device register map contents.
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 To reduce power consumption, avoid prolonged I2C communication with the device.
 The host should wait for 350 ms if Noise Immunity is “Normal” or 1000 ms if Noise Immunity is “High” after device
power-on before initiating any I2C communication. Otherwise, the device NACKs any such communication.
 The host should wait for a minimum of 60 ms after any I2C transaction before initiating a new transaction.
 The host should wait for 350 ms if Noise Immunity is “Normal” or 1000 ms if Noise Immunity is “High” after “Save
to Flash” or “Software reset” commands are issued before initiating any I2C communication.
 The device should be in Operating Mode in runtime.
 The host should not initiate a new START condition for the device without initiating a STOP condition for the
previous I2C communication. This is also called Repeat Start condition.
 The host should maintain a minimum of 60 ms between consecutive I2C transactions.

If the host initiates another I2C transaction before this time, it will receive the same data as in the previous
transaction.

If the host writes to the same register as the one in the previous transaction within this time, the old data is
lost.

If the host writes to a different register than the one in the previous transaction within this time, the register
keeps this data. The data from the previous transaction is not lost.
3.3 Design Toolbox
The Design Toolbox helps you to design a CY8CMBR2110 CapSense solution. It offers basic information about the
board layout and feature settings and recommends whether the design is fit for mass production.
3.3.1 General Layout Guidelines
Figure 3-28 summarizes the layout guidelines for the CY8CMBR2110. These guidelines are discussed in Electrical
and Mechanical Design Considerations. For a thorough treatment of this material, see Getting Started with
CapSense.
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Figure 3-28. Design Layout Recommendations
3.3.2 Layout Estimator
The Layout Estimator provides the minimum button size and maximum trace length recommendation based on the
intended end-system requirements and industrial design. The inputs include the overlay material, overlay thickness,
trace capacitance of circuit board material, and CapSense button sensitivity. See Figure 3-29, Table B, to learn the
dielectric constants for different overlay materials and the trace capacitance per unit length for different PCBs. Table
A calculates the minimum button diameter and maximum trace length for the design, based on three system noise
conditions. “Low”, “Medium”, and “High” noise conditions are relative figures of merit to help you with button
development. Noise conditions can vary from button to button based on the end-system environment. If the noise
conditions are unknown, use medium as the starting point. The actual noise seen at each button will be determined
during Design Validation .
Use the outputs of this sheet to guide the button board layout process, and then check the design prior to prototyping
with the CP, Power Consumption and Response Time Calculator sheet, as detailed in CP, Power Consumption and
Response Time Calculator.
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Figure 3-29. Layout Estimator
Inputs
 Overlay thickness
 Overlay dielectric constant
 Capacitance of trace per inch of board
 CSx sensitivity
Outputs
 Recommended minimum button diameter and maximum trace length for different noise conditions
 Button-to-ground clearance
The diameter of each button can vary based on the variation in noise in each button.
3.3.3 CP, Power Consumption and Response Time Calculator
After the board layout has been completed, the Power Consumption and Response Time Calculator shown in
Figure 3-30 checks the design before building the button board prototype. To verify the CP value of each button,
insert the button diameters and trace lengths into Table A. After you enter the information, the toolbox confirms
whether each button is within the specified CP range of 5—40 pF.
The power calculator in Table B is used to optimize power consumption. Power consumption is a function of the
button scan rate, noise immunity level, and the percentage of active time. Active time is calculated by multiplying the
average number of button touches per hour by the maximum of the following three values: Button touch time, Buzzer
ON time or Button Touch LED Effects. This is converted into the percentage of active time, and the power
consumption is calculated accordingly. Ensure that you do not keep all the following input cells empty (or zero) at the
same time:
1.
Average number of button touches per hour
2.
Average button touch time
3.
Average Buzzer ON time
4.
Average Button Touch LED Effects time
Table C outputs the button response time based on the inputs in Tables A and B. The debounce value affects the
button response time.
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Figure 3-30. CP, Power Consumption and Response Time Calculator
Inputs
 Button diameter and trace length of CS0—CS9 as designed in layout
 Sensitivity of CS0—CS9
 Button Scan Rate offset
 Design optimization
 Noise immunity level
 CS0 Debounce
 CS1—CS9 Debounce
 Average number of button touch per hour
 Average button touch time
 Average Buzzer ON time
 Average Button Touch LED Effects time
 Standby Mode LED Brightness
 Current consumption calculation factor
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Outputs
 CP for each button (confirms whether the CP values are within the specified range of 5—40 pF)
 Current consumption per button
 Button response time
3.3.4 Design Validation
After you have built and tested the prototype board, use the EZ-Click Customizer Tool to capture the raw count, noise
count, and CP for all buttons (See EZ-Click User Guide). You can use this information and the design validation sheet
to validate the design, as detailed in Design Validation .
Table A shows the various design parameter values, taken from the previous sheets, so you do not need to enter any
data in this sheet. This sheet provides a pass/fail grade for the prototype board. If your design fails, you can redesign
your system by entering new values in Table A, and you will receive further recommendations and results. If your
design passes, leave blank the “New value” column in Table A.
Table B shows the button sensitivity values, taken from the C P, Power Consumption and Response Time Calculator
Sheet. If your design fails, you can redesign your button sensitivity by entering the new values. If your design passes,
you can leave blank the “New value” column in Table B.
Figure 3-31. Design Validation
To use the EZ-Click Customizer Tool to enter data into Table D, follow these steps:
1.
Power-on the device and connect it to your computer using the USB-I2C Bridge (CY3240-I2USB Bridge). Refer
to AN2397 – CapSense Data Viewing Tools for (USB-I2C Bridge) (CY3240-I2USB Bridge) details.
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2.
Open the EZ-Click Customizer Tool and create a new project. Select Cypress device CY8CMBR2110. Select the
port you are using from the Port selection window and click Connect.
3.
Go to Device Config tab and select the number of buttons in your design. Assign the CapSense pins to the
corresponding buttons if required. Set the finger threshold or select Automatic Threshold.
4.
Go to CapSense output tab and select Button Specific Output view.
5.
Select the button whose CapSense output you want to see. Select the “Raw Count vs Baseline” graph.
6.
Observe the raw count graph and note the average Raw Counts for 300 samples. Also note the Button C P.
7.
Calculate Noise Counts based on the following equation:
Noise Counts = Maximum Raw Counts - Minimum Raw Counts (for 300 samples)
8.
Enter this data in Table D to find the current consumption values and determine if your design is ready for mass
production.
Inputs
 Raw Counts
 Noise Counts
 Button CP
 If the design fails, note the following:

New overlay thickness, overlay material permittivity, button diameter for each individual button, and trace
capacitance

CSx sensitivity
Outputs
 Current consumption per button
 Design change recommendations. The Design Toolbox makes recommendations based on the actual values
from the design if the button size or trace lengths are outside of best design practices.
If the button board does not pass, the Design Toolbox will offer recommendations to guide you to a passing outcome.
You can change four areas to remedy a failing design: button size, trace length, overlay material, and overlay
thickness. Changing the button size or trace length requires a board spin, while changing the overlay material,
thickness, or both, may result in a passing design. The best solution depends on where your design is in the
development cycle as well as your end-system requirements.
3.4 Configuring the CY8CMBR2110
CY8CMBR2110 can be configured using one of the following methods:
1. EZ-Click Customizer Tool
2. Configuring the Device using a Host Processor
3. Third-party Programmer
The general procedure to configure the CY8CMBR2110 device is listed in steps. These procedures are common for
all the configuration methods. The EZ-Click Customizer Tool takes care of this procedure automatically but the host
processor must follow these procedures:
1.
Change the device mode to LED Configuration mode.
2.
Wait 55 ms.
3.
Write to all of the configuration registers in the LED Configuration mode.
4.
Wait 55 ms.
5.
Change the device mode to Device Configuration mode.
6.
Wait 55 ms.
7.
Write to all of the configuration registers in the Device Configuration mode.
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8.
Calculate the checksum and enter it in the “Checksum_MSB” (0x1E) and “Checksum_LSB” (0x1F) registers (in
the Device Configuration mode).
Checksum: The checksum is the sum of the values of the registers (0x01—0x1F) in the LED Configuration
mode and the registers (0x01—0x1D) in the Device Configuration mode. The checksum also includes the
values of any reserved register bits. The host should not write to these bits and should add 0 for any such
bit, when calculating the checksum.
Checksum_Flash_xxx registers (in Operating mode) indicate the checksum stored in the flash.
Checksum_RAM_xxx registers (in Operating mode) indicate the checksum calculated by the device for the
current configuration and stored in the RAM.
9.
Wait 55 ms.
10. Read the “Checksum matched” bit in the Host_Mode register (in Device Configuration mode), and verify that it is
set to 1. If this bit is not set, restart at step one and reconfigure the device. The host should keep a backup of the
configuration data if this is needed.
“Checksum matched” bit: The CY8CMBR2110 calculates the checksum and compares that with the
Checksum register value entered by the host. If both the values match, the “Checksum matched” bit in the
Host_Mode register is set to 1. If the values do not match, it indicates a possible I2C write error, and this bit
is cleared to 0. The host can read the Checksum_RAM_xxx register (in Operating mode) to get the device
calculated checksum.
11. If the “Checksum matched” bit is set to 1, then set the “Save to Flash” bit in the Host_mode register.
Save to Flash: On a “save to flash”, the following sequence is executed:
(i)
The device copies the 64-byte data (in LED Configuration mode and Device Configuration
mode) to the flash.
(ii) A software reset is done.
(iii) After the software reset, the device mode is Operating mode.
Any configuration changes are not applicable unless you save to flash. A “save to flash” is useful when the
device has to be configured only once for all future operations. During a save to flash, the device’s power
supply must be stable, with VDD fluctuations limited to ±5%.
12. After a “save to flash”, wait for (TSAVE_FLASH + Device initialization) time. TSAVE_FLASH is mentioned in the Flash
Write Time Specifications in the CY8CMBR2110 Datasheet. The device initialization time is 350 ms if the Noise
Immunity is “Normal” or 1000 ms if the Noise Immunity is “High”.
13. Read the “Factory defaults loaded” bit in Device_Stat register (in Operating mode).
Factory Defaults Loaded: On every reset, the device loads the RAM with the flash content and verifies the
RAM checksum with the flash checksum to ensure there is no flash corruption. If the checksum differs, then
the device identifies it as a flash corruption, loads the factory defaults value in the RAM, and sets the
“Factory defaults loaded” bit. This resets any register values previously changed by the host. Factory default
values for each register are given in the Register Map.
If the factory defaults are loaded, the I2C address of the device also changes from the current address, set
by the host, to the default address, 37h. The host must use the default I2C address on the I2C bus to
communicate with the CY8CMBR2110 after factory defaults are loaded.
14. If the “Factory defaults loaded” bit is set, then the flash is corrupted, and the host needs to reconfigure the device
from step one. If this bit is clear, device configuration is successful.
Note The details of different modes and registers referred to in these steps are available in the CY8CMBR2110
Datasheet.
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3.4.1 EZ-Click Customizer Tool
The EZ-Click Customizer Tool is a simple and intuitive graphical user interface used to configure the device. It takes
all the required parameters and configures the device using an I 2C interface.
Figure 3-32: EZ-Click Customizer Tool
The EZ-Click Customizer Tool displays real-time CapSense data from the device. You can see both button-specific
and parameter-specific data, including CapSense button status, CP, Raw Counts, Finger threshold, and SNR. The
tool can be used for production line testing because it displays System Diagnostics results and CapSense button
SNR, and indicates whether the SNR meets your requirements. For more information on this tool, refer to the EZClick User Guide.
You can save the configuration and use it on a different sample. You can also use the tool to generate a configuration
file, including the required I2C instructions, and use it to configure the device. To do this, open the configuration file in
Bridge Control Panel (refer to AN2397 - CapSense Data Viewing Tools to learn more about Bridge Control Panel)
and send the commands to the device over the USB-I2C Bridge (CY3240-I2USB Bridge). Figure 3-33 shows an
example configuration file.
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Figure 3-33. Example Configuration File Generated by the EZ-Click Customizer Tool
3.4.2 Configuring the Device using a Host Processor
To configure the CY8CMBR2110 device using a Host processor, there is a comprehensive list of APIs and these
APIs are to be called from the Host processor in a specific order. These APIs use I2C communication to configure the
device features, read CapSense data, drive host control GPOs, perform production line tests, configure power
consumption settings, and so on. You can download the source code from http://www.cypress.com/?rID=74590.
The advantages of using a Host processor to configure the CY8CMBR2110 device are as follows:


In-system configuration - no need to take the device (chip) out of the board
Run time configuration - modifying the features dynamically by a host processor
The APIs are primarily divided as high-level APIs and low-level APIs. High-level APIs are hardware (platform)
independent and work on any host processor. The low-level APIs are developed for the CY8C29466-24PXI device,
and it is hardware (platform) dependent. If you have a different host processor in your application, you need to modify
the low-level API firmware.
3.4.2.1 High-Level APIs
High-level APIs can be used to enable or disable Button Touch LED Brightness, set Finger Threshold parameters,
configure scan rate, change I2C address, and many other functions.
High-level APIs contain code to read or write the appropriate register of the CY8CMBR2110 and calculate the
checksum of the configurations. They call low-level APIs that are host processor specific and implement the physical
I2C communication between the host processor and the device.
The high-level API header file (High_Level_API.h) contains function prototypes for all of the high-level APIs. This
header file needs to be included in the required .C file when configuring the CY8CMBR2110 device. High-level APIs
use the macros defined in High_Level_API.h for internal configuration. You must not change the macros.
For example:
#define I2C_CFG_REG
(0x01)
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3.4.2.2 Low-Level APIs
Low-level APIs are used in the host processor to enable physical I 2C communication with the device. The low-level
APIs provided here use the PSoC I2CHW User Module to perform read and write operations. You may need to
modify the low-level API code depending on how you implement I2C protocol.
The low-level API header file (Low_Level_API.h) contains function prototypes for the low-level APIs and macros used
by the low-level APIs. The macros are mainly used for I2C communication and the software delay routine. These
macros are defined for the CY8C29466-24PXI device. You need to change the definitions to work with your host I2C
implementation.
For example, if the CY8CMBR2110 device NACKs, the I2CHW User Module in CY8C29466-24PXI (PSoC1) returns
0x00. Therefore, the macro I2C_NACK is defined as 0x00. If you are using a different host processor that returns a
different value when it NACKs, you need to modify I2C_NACK to match.
The software delay API is required to provide a delay equal to the Button Scan Rate. This delay is required after
every write instruction. If you wish to implement this delay using a hardware resource (timer), you can disable the
software delay routine by clearing the corresponding macro as described in Table 3-7.
Macros that do not depend on the host controller are listed in Table 3-6. Macros that you may need to change based
on the host controller you are using are listed in Table 3-7.
Table 3-6: Macros Not Dependent on the Host Controller
Macro Name
Usage
FLASH_WRITE_TIME
The amount of time it takes the CY8CMBR2110 device to properly save the data after a
save to flash command is issued
TOTAL_BUTTON_COUNT
The maximum number of buttons in the CY8CMBR2110 device
FACTORY_DEFAULT_CHECKSUM
The factory default checksum of the CY8CMBR2110 device
DEFAULT_SLAVE_ADDRESS
The factory default I2C address of the CY8CMBR2110 device
DELAY_CONST
Used to calculate number of iterations required for the software delay
SLAVE_NACK
Used to clear the I2C flag, when the CY8CMBR2110 device NACKs
SLAVE_ACK
Used to set the I2C flag, when the CY8CMBR2110 device ACKs
SLAVE_BUF_PTR
Used to set the host I2C buffer pointer to the specific register address on the register map
Table 3-7: Macros Dependent on the Host Controller
Macro Name
Usage
I2C_WRITE_COMPLETE
Checks if the I2C write operation to the CY8CMBR2110 device is complete. The I2CHW
User Module returns 0x50 when the write operation is complete.
NACK_RETRY_LIMIT
Defines the number of times the host processor retries when the CY8CMBR2110 device
NACKs. The typical value is 20. You may change this value to work with your application.
DELAY_ROUTINE_USED
Used to enable/disable the software delay routine. A value of 1 enables the software
delay, while 0 disables it. If you are using a hardware resource to implement the
delay, you should disable the software delay routine.
Note The software delay routine is a blocking code. It stalls the CPU for a definite time.
I2C_NACK
Used to check if the CY8CMBR2110 device NACKed the current I2C operation. The
I2CHW User Module returns 0x00 when the write/read operation is NACKed.
I2C_READ_COMPLETE
Checks if the I2C write operation to the CY8CMBR2110 device is complete. The I2CHW
User Module returns 0x15 when the write operation is complete.
NEW_SLAVE_ADDRESS
The value of the new slave address. If the host changes the default slave address of the
CY8CMBR2110 device using the MBR_SetI2CSlaveAddress API, it needs to re-define
this macro with the new slave address.
CLOCK_FREQUENCY
The host controller clock frequency in MHz. For the PSoC 1 Host device, the clock
frequency is 24 MHz.
MACHINE_CYCLES
The number of machine cycles taken to execute the while loop in the software delay
routine. The value of MACHINE_CYCLES is 97 on building with the ImageCraft compiler
(refer to MBR_Delay).
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3.4.2.3 MBR_WriteBytes
This API initiates an I2C write operation between the CY8CMBR2110 device and host processor. The function
prototype is given in Section 7.2.2.
Note For the write operation, there is a buffer defined in the host. The high-level API passes the buffer to the write
API and the buffer is in the form of a BYTE array (refer to Data Types). Upon writing, the first BYTE (byte[0]) holds
the base pointer and rest of the bytes (byte[1], byte[2]…) have the data. Because the base pointer is set to “location
to be written in the register map of CY8CMBR2110”, the write operation begins from that location.
High-level APIs pass the I2C buffer pointer and the number of bytes to be written. MBR_WriteBytes does the
following:
1.
2.
3.
4.
Initiates an I2C write operation to the CY8CMBR2110 device
Waits until the transaction ends
Checks if the transaction worked properly
If the transaction did not work properly, it retries the write operation for up to the value of the macro
NACK_RETRY_LIMIT
3.4.2.4 MBR_ReadBytes
This API initiates an I2C read operation between the CY8CMBR2110 device and host processor. The function
prototype is given in section 7.2.2.
Note Upon reading, the host buffer is updated with the required data from the location 0x00 of the device register
map as byte[0] will contain the data in location 0x00, byte [1] will have data in location 0x01,etc.The read operation
always begin from location 0x00 of all the register maps.
High level APIs pass the I2C buffer and the number of bytes to be read. MBR_ReadBytes does the following:
1.
2.
3.
4.
5.
6.
Gets the I2C buffer address and the number of bytes that will be read from the device
Sets the slave pointer to the location 0x00
Initiates an I2C read operation from the CY8CMBR2110 device
Waits until the transaction ends
Checks if the transaction worked properly
If the transaction did not work properly, it retries the read operation for up to the value of the macro
NACK_RETRY_LIMIT
3.4.2.5 MBR_Delay
This API generates a software delay using a while loop that is executed a specified number of times. The function
prototype is given in section 7.2.2. The number of loop iterations can be calculated using the following formula:
    =
required delay time (ms) × clock frequency (MHz)× 1000
machine cycles required to execute the while loop
Equation 5
You need to calculate the number of machine cycles (total assembly-level instruction cycles) required to execute the
while loop in the host machine. For a PSoC 1 host using the ImageCraft Pro compiler, the macro
MACHINE_CYCLES is 97. You need to modify this value based on the compiler and host processor you are using.
Note The CPU is completely blocked for the entire delay time.
3.4.2.6 Guidelines to Configure the CY8CMBR2110 Device


The high-level APIs need to be called in a specific order when configuring the CY8CMBR2110 device.
Figure 3-34 illustrates the correct order.
Check your I2C communication status in the host processor after calling the MBR_Initialization API. This API
should be called before any other API call. For example, when the transaction gets ACK, the variable
“gbI2CFlag” in low-level APIs is set to 1, otherwise it will be set to zero. You can check this variable for
proper transaction. You can also check your own I 2C registers in your host processor for the indication of
NACK or ACK.
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











Do not switch between register map modes until you have completed configuring all of the features for that
register map mode. For example, do not configure one feature in the LED configuration mode, switch to the
device configuration mode, and then return to configuring features in the LED configuration mode. Switching
between register map modes consumes time. Therefore, configure all the features in the LED configuration
mode and then switch to device configuration.
Pass the correct arguments to the high-level APIs as defined in the section, APIs for CY8CMBR2110
Configuration.
Since the high-level APIs themselves calculate the checksum of the configurations, you need not take care
of checksum calculations.
Host controlled GPOs must be configured after the save to flash because the save to flash command issues
a software reset, which clears the Host controlled GPO configurations.
LED effects are defined in groups of GPOs (GPO123, GPO456, and GPO789) except for GPO0. The
configuration must match for all of the GPOs in a group. For example, do not pass different LED
configurations to GPO1 and GPO2. After you configure GPO1, the configuration applies to GPO2 and GPO3
because they share a register and if you again configure different LED effects for GPO2, that will be
applicable to GPO1,3.
When setting the Finger threshold values of the buttons, clear or disable the Automatic Threshold feature
using the MBR_SetAdaptiveThreshold API (see High-Level APIs).
When using LED effects, enable the effect before configuring the features of that effect. For example, enable
button touch LED effects and then configure all the features corresponding to button touch LED effects.
The deep sleep API must be called using the procedure in Deep Sleep Mode.
Do not configure the LED ON time and also enable Toggle ON/OFF. LED ON time will be disabled if Toggle
ON/OFF is enabled.
Do not configure the LED ON time and also enable Button Touch LED Effects. LED ON time will be disabled
if Button Touch LED Effects is enabled.
Do not enable Toggle ON/OFF and Last Button LED Effect. The Last Button LED Effect will be disabled if
Toggle ON/OFF is enabled.
All of the read APIs such as System Diagnostics, Sensor Current Status, Sensor Latch Status, Sensor SNR,
and Debug Data can be called directly without saving to flash.
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CapSense Schematic Design
Figure 3-34: High-Level API Flow Chart
Start
Call MBR_Initialization()
Call required APIs to read
CapSense information,
Device ID, firmware
revision
Read information from
CY8CMBR2110
Type of operation
required?
System Diagnostics /
Production line debug
Configure
CY8CMBR2110
Stop
Call required APIs to read
System Diagnostics /
debug data
Stop
Call required APIs for LED Configuration
Call required APIs for Device Configuration
No.
Possible I2C
write error
Call MBR_SetChecksum()
Call
MBR_ReadChecksumMatch()
Save to Flash
not proper
Is checksum
matching?
Yes. I2C writes are OK.
Call MBR_SaveSettingsToFlash()
Is Save to Flash
proper?
Yes
Stop
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CapSense Schematic Design
3.4.2.7 Input Header
Inputs.h includes macro definitions for high-level API inputs. Use these macros when passing arguments to high-level
APIs. For example, pass the FEATURE_ENABLE macro as an argument when you enable a feature. Some highlevel APIs do not have macros for their input. For example, the MBR_SetScanRate() API does not have any macro
definition for the input, you need to pass the decimal value of 0 to 31 as the input to the function parameter. Refer to
the function prototype of every high-level API in the section, APIs for CY8CMBR2110 Configuration, before passing
the parameters. You should not change these macro definitions. These macros help you to pass proper parameters
to the high-level APIs.
Note The header of every high-level API also lists all of the possible macros that can be passed to it as arguments.
3.4.2.8 Data Types
The amount of memory allocated for each data type depends upon the complier. Data types char, int, and long are
type-defined and used by the high-level APIs to configure the CY8CMBR2110 device. The data types are as follows:
 unsigned char type-defined to BOOL
 unsigned char type-defined to BYTE
 unsigned int type-defined to WORD
 unsigned long type-defined to DWORD
 signed char type-defined to CHAR
 signed int type-defined to INT
 signed long type-defined to LONG
These values are based on the assumption that char, int, and long data types take 8, 16, and 32 bits of memory
respectively. If these assumptions are not valid for your host complier, modify the type-definitions in Low_Level_API.h
and High_Level_API.h.
3.4.2.9 Sample Project
The sample project is created to configure the CY8CMBR2110 device using CY8C29466-24PXI (PSoC) as the host
device, which can be downloaded from http://www.cypress.com/?rID=74590. This code is implemented with PSoC
Designer 5.2 and ImageCraft compiler in CY3210-PSoC-EVAL-kit. The sample code configures the following
features:
1.
Reads the number of working sensors (number of valid sensors passed the system diagnostics)
2.
Enables concurrent power-on LED effects for all the GPOs with 600 ms of ramp-up, ramp-down time
3.
Enables a high time of 600 ms with 80% brightness level for GPO0, GPO123, 20% brightness level for
GPO456, and 100% for GPO789 on Power-On LED Effects
4.
Sets the repeat rate equal to one for the GPO0 on Power-On LED Effect
5.
Configures AC-1 pin Buzzer in LOW idle state with 4-KHz buzzer frequency and 200 ms of buzzer duration
6.
Sets the debounce value to 100 (response time for consecutive button touches to 1225 ms) for the CS0
button
7.
Sets sensitivity value of 2 (Medium) for the CS0 button
8.
Enables toggle feature for button CS0 button
9.
Enables the FSS feature for all the buttons
10. Writes the checksum calculated by the host to CY8CMBR2110 device
11. Verifies the checksum match condition
12. Save the configurations to the Flash if the checksum match condition is true
13. Sets the HGPO1 state to HIGH
Note HGPO1 is configured to be HIGH after save to flash is complete. On the next reset, HGPO1 is cleared to
LOW. If you need to see the Power-On LED Effects, you must give a hardware reset to the device, which clears
the HGPO1.
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CapSense Schematic Design
3.4.3 Third-party Programmer
To configure the large number of devices, Cypress recommends a third-party vendor to perform automated
programming on the devices. For this, you must give the hex file of your configuration, generated by EZ-Click
Customizer Tool, to Hilo systems (a third-party programmer).
Contact http://www.hilosystems.com.tw/en/index.aspx for further information.
3.5 CY8CMBR2110 Reset
The CY8CMBR2110 can be reset using hardware or software.
3.5.1 Hardware Reset
On a hardware reset, the LED Configuration mode and Device Configuration mode register values are loaded from
the flash into the RAM. All of the device blocks are initialized, System Diagnostics are performed, and an initial 5 ms
pulse is sent out on any GPOx associated with a failing CSx. This is done within 350 ms if Noise Immunity is “Normal”
or 1000 ms if Noise Immunity is “High”. If Power-On LED Effects are enabled, they are then seen on all the remaining
GPOs. After the LED Effects, the device is in Operating mode, and normal operation begins.
Hardware reset is done by toggling power on the CY8CMBR2110 pins using the power supply or XRES.
3.5.1.1 Power Reset
For a power reset, turn off the external power supply to the device’s VDD line, ensuring that VDD drops below 100 mV,
and then turn power back on. On a power reset, a high-going pulse of 16 ms is seen on the HostControlGPO1 pin.
3.5.1.2 XRES Reset
For a XRES reset, pull the device’s XRES pin HIGH and then LOW. On a XRES reset, a pulse is not seen on
HostControlGPO1 pin.
3.5.2 Software Reset
Software reset is done by writing a 1 to the “Software Reset” bit in the Host_Mode register (in Operating mode). On a
software reset, the LED Configuration mode and Device Configuration mode register values are loaded from the flash
into the RAM. The device auto-clears the “Software Reset” bit, and all of the device blocks are initialized. This is done
within 350 ms if Noise Immunity is “Normal” or 1000 ms if Noise Immunity is “High”. The device is in Operating mode,
and normal operation begins. No System Diagnostics are performed, and Power-On LED Effects do not occur. If the
user has configured the device for Power-On LED Effects and saved the settings to flash, a hardware reset must be
done to see the Power-On LED Effects.
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4. Electrical and Mechanical Design
Considerations
When designing a capacitive touch sense technology into your application, it is crucial to remember that the
CapSense device exists within a larger framework. Careful attention to every detail, including PCB layout, user
interface, and end-user operating environment, leads to robust and reliable system performance. For in-depth
information, refer to Getting Started with CapSense.
4.1 Overlay Selection
In CapSense Schematic Design, Equation 1 describes finger capacitance:
 =
0  

Where:
ε0 = Free space permittivity
εr = Dielectric constant of overlay
A = Area of finger and button pad overlap
D = Overlay thickness
To increase the CapSense signal strength, choose an overlay material with a higher dielectric constant, decrease the
overlay thickness, and increase the button diameter. The Design Toolbox helps you design a robust and reliable
CY8CMBR2110 solution, as discussed in the chapter CapSense Schematic Design.
Table 4-1. Overlay Material Dielectric Strength
Material
Breakdown Voltage (V/mm)
Minimum Overlay Thickness at 12 kV (mm)
10
Air
1200–2800
Wood – dry
3900
3
Glass – common
7900
1.5
Glass – Borosilicate (Pyrex®))
13,000
0.9
PMMA Plastic (Plexiglas®)
13,000
0.9
ABS
16,000
0.8
Polycarbonate (Lexan®)
16,000
0.8
Formica
18,000
0.7
FR-4
28,000
0.4
PET Film – (Mylar®)
280,000
0.04
Polymide film – (Kapton®)
290,000
0.04
Conductive material cannot be used as an overlay because it interferes with the electric field pattern. Therefore, do
not use paint containing metal particles.
Bonding Overlay to PCB
Because the dielectric constant of air is very low, an air gap between the overlay and the button degrades the
performance of the button. To eliminate the gap, use a nonconductive adhesive to bond the overlay to the CapSense
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Electrical and Mechanical Design Considerations
PCB. A transparent acrylic adhesive film from 3M™ called 200MP is qualified for use in CapSense applications. This
adhesive is dispensed from paper-backed tape rolls (3M product numbers 467MP and 468MP).
4.2 ESD Protection
Robust ESD tolerance is a natural byproduct of thoughtful system design. By considering how the contact discharge
occurs in your end product, particularly in your user interface, you can withstand an 18-kV discharge event without
damaging the CapSense controller.
CapSense controller pins can withstand a direct 12-kV event. In most cases, the overlay material provides sufficient
ESD protection for the controller pins. Table 4-1 lists the thickness of various overlay materials required to protect the
CapSense buttons from a 12-kV discharge, as specified in IEC 61000-4-2. If the overlay material does not provide
sufficient ESD protection, apply countermeasures in the following order: prevent, redirect, clamp.
4.2.1 Prevent
Make sure all paths on the touch surface have a breakdown voltage greater than potential high-voltage contacts. In
addition, design your system to maintain an appropriate distance between the CapSense controller and possible
sources of ESD. If it is not possible to maintain adequate distance, place a protective layer of a high-breakdownvoltage material between the ESD source and CapSense controller. For example, one layer of 5-mil-thick Kapton®
tape can withstand 18 kV.
4.2.2 Redirect
If your product is densely packed, you might not be able to prevent the discharge event. In this case, you can protect
the CapSense controller by controlling where the discharge occurs. Place a guard ring on the perimeter of the circuit
board that is connected to chassis ground. As recommended in PCB Layout Guidelines, using a hatched ground
plane around the button or slider can redirect the ESD event away from the button and CapSense controller.
4.2.3 Clamp
Because CapSense buttons are purposefully placed close to the touch surface, it may not be practical to redirect the
discharge path. In this case, consider including series resistors or special-purpose ESD protection devices.
The recommended series resistance value is 560 Ω.
A more effective method is to put special-purpose ESD protection devices on the vulnerable traces. Note that ESD
protection devices for CapSense need to be low in capacitance. Table 4-2 lists devices recommended for use with
CapSense controllers.
Table 4-2. Low-Capacitance ESD Protection Devices Recommended for CapSense
ESD Protection Device
Manufacturer
Part Number
Input
Capacitance
Leakage
Current
Contact Discharge
Maximum Limit
Air Discharge
Maximum Limit
Littelfuse
SP723
5 pF
2 nA
8 kV
15 kV
Vishay
VBUS05L1-DD1
0.3 pF
0.1 µA
±15 kV
±16 kV
NXP
NUP1301
0.75 pF
30 nA
8 kV
15 kV
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Electrical and Mechanical Design Considerations
4.3 Electromagnetic Compatibility (EMC) Considerations
4.3.1 Radiated Interference
Radiated electrical energy can influence system measurements and the operation of the processor core. The
interference enters the CY8CMBR2110 chip at the PCB level, through CapSense button traces and any other digital
or analog inputs. The layout guidelines for minimizing the effects of RF interference follow:
 Ground plane: provide a ground plane on the PCB.
 Series resistor: place series resistors within 10 mm of the CapSense controller pins.

The recommended series resistance for CapSense input lines is 560 Ω.
 Trace length: Minimize trace length whenever possible.
 Current loop area: Minimize the return path for current. To reduce the impact of parasitic capacitance, hatched
ground is given within 1 cm of the buttons and traces, instead of solid fill.
 RF source location: Partition systems with noise sources, such as LCD inverters and switched-mode power
supplies (SMPS), to keep the interference separated from CapSense inputs. Shielding the power supply is
another common technique to prevent interference.
4.3.2 Conducted Immunity and Emissions
Noise entering a system through interconnections with other systems is referred to as conducted noise. Examples
include power and communication lines. Because the CapSense controllers are low-power devices, you must avoid
conducted emissions. The following guidelines will help to reduce conducted emission and immunity:
 Use decoupling capacitors recommended in the datasheet.
 Add a bidirectional filter on the input connected to the system power supply. The filter is effective for both
conducted emissions and immunity. A pi-filter can prevent power supply noise from affecting sensitive parts and
prevent the switching noise of the part itself from coupling back onto the power planes.
 If the CapSense controller PCB is connected to the power supply by a cable, minimize the cable length and
consider using a shielded cable.
 To filter out high-frequency noise, place a ferrite bead around power supply or communication lines.
4.4 PCB Layout Guidelines
The Design Toolbox will help you design a robust CY8CMBR2110 CapSense PCB layout, as discussed in the
General Layout Guidelines.
If your design uses the GPOs to sink current to the CapSense controller, and there is a lot of noise in the CapSense
system, use series resistors on all of the GPOs to limit sink current. Sink current limit is determined by the maximum
button CP in your design at 5 V, as show in Table 4-3.
Table 4-3. GPO Sink Current Limit for Low Output Voltage
Button CP Range
Sink Current Limit per GPO
Sink Current Limit for Device
5 pF ≤ CP ≤ 12 pF
25 mA
120 mA
12 pF ≤ CP ≤ 21 pF
20 mA
20 mA
21 pF ≤ CP ≤ 40 pF
6 mA
6 mA
Detailed PCB layout guidelines are available in Getting Started with CapSense.
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5. Low-Power Design Considerations
5.1 System Design Recommendations
Cypress’s CY8CMBR2110 is designed to meet the low-power requirements of battery-powered applications.
To minimize power consumption, take these steps:
 Ground all unused CapSense inputs
 Minimize CP using the design guidelines in Getting Started with CapSense
 Reduce supply voltage
 Reduce the sensitivity of CSx buttons, refer to Sensitivity Control
 Configure the design to be power consumption-optimized, refer to Button Scan Rate
 Use "High" noise immunity level only if required, refer to Noise Immunity
 Use a higher Button Scan Rate or Deep Sleep operating mode, refer to Button Scan Rate
5.2 Calculating Average Power
The Design Toolbox automates the power optimization calculations described in this section. The average power
consumed by the CY8CMBR2110 is determined by calculating the parameters below:
 Button scan rate, TR
 Scan time, TS
 Average current in a NO TOUCH state, IAVE_NT
 Average current in a TOUCH state, IAVE_T
 Percentage of active time, P
 Average use current, IAVE_U
 Average current, IAVE
 Average power, PAVE
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Low-Power Design Considerations
5.2.1 Button Scan Rate (TR)
You control the button scan rate through the Register Map settings in the CY8CMBR2110. Based on the register
value, an offset is obtained and added to a constant to get the actual button scan rate. The range of the offset value
is 0—506 ms.
 =     +    
Equation 6
Table 3-5 shows how to determine the Button Scan Rate constant.
5.2.1.1 Response Time
Response time is the minimum time the button CSx should be touched for the device to detect as valid button touch
and produce a signal on GPOx.
Response times are calculated using the following equation:
Equation 7
If Noise Immunity is “Normal”:
 =    
+ [    × { (( − 1)/3) + 1}]
 =    + [    × { (( − 1)/3) + 1}]
If Noise Immunity is “High”:
 =     + [    × ]
 =    + [    × ]
Where:
RTCBT = response time for consecutive button touch after first button touch
RTFBT = response time for first button touch
Debounce for CS1—CS9 = 1—255
Debounce for CS0 = 1—255
Rounddown is the greatest integer less than or equal to ((Debounce – 1)/3)
If you need to change your design configuration from "Normal" Noise Immunity to "High" Noise Immunity, reduce the
debounce value to maintain the Response Time.
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Low-Power Design Considerations
5.2.2 Scan Time (TS)
To calculate approximate scan time, use the following equation:
Equation 8
When Noise Immunity is “Normal”:
 = [0.375  × (0 + 1 + 2 + ⋯ + 9 )] + 
When Noise Immunity is “High”:
 = [0.375  × (0 + 1 + 2 + ⋯ + 9 ) × 3] + 
Where:
KCSX = button sensitivity constant for CSx, from Table 5-1.
TFW = Firmware execution time, from Table 5-2.
Table 5-1. Button Sensitivity Constant
CP (pF)[7]
Button Sensitivity Constant (K)
Button connected to GND
0
5 pF ≤ CP ≤ 10 pF
1
10 pF < CP ≤ 22 pF
2
22 pF < CP ≤ 40 pF
4
Button connected to GND
0
5 pF ≤ CP ≤ 18 pF
1
18 pF < CP ≤ 38 pF
2
38 pF < CP ≤ 40 pF
4
Button connected to GND
0
5 pF ≤ CP ≤ 12 pF
0.5
12 pF < CP ≤ 26 pF
1
26 pF < CP ≤ 40 pF
2
CSx Sensitivity (pF)
High
Medium
Low
Table 5-2. Average Current Parameters
Parameter
Typical
Maximum
TFW
6.00 ms
6.50 ms
TS
From Equation 7
+5% from TYP value
TR
From Equation 5
+10% from TYP value
ISLEEP
9.52 µA
14.2 µA
IACTIVE
3.4 mA
4.00 mA
7
CP limits are approximate and can have ±2 pF variation
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Low-Power Design Considerations
5.2.3 Average Current in NO TOUCH State (IAVE_NT)
_ = (
 −
×  ) + (



×  )
Equation 9
Where:
TR = button scan rate
TS = scan time
ISLEEP = current consumed by CY8CMBR2110 during Low Power Sleep mode, from Table 5-2.
IACTIVE = current consumed by CY8CMBR2110 during active operation, from Table 5-2.
If Standby Mode LED Brightness is enabled:
_ = 
5.2.4 Average Current in TOUCH State (IAVE_T)
_ = (
 −

×  ) + (


×  )
Equation 10
Where:
TS = Scan time
CBS = Button scan rate constant, from Table 3-5.
ISLEEP = current consumed by CY8CMBR2110 during Low Power Sleep mode, from Table 5-2.
IACTIVE = current consumed by CY8CMBR2110 during active operation, from Table 5-2.
If Standby Mode LED Brightness is enabled:
_ = 
5.2.5 Percentage of Active Time (P)
When you touch a button, the device’s active time is calculated (in ms) using the number of button touches per hour
and the maximum of the following three values:
1.
2.
3.
Average button touch time
Average Buzzer ON time
Average Button Touch LED Effects time
Equation 11
  = ( ℎ ,   ,  ℎ   )
× (   ℎ  ℎ)
The percentage of active time is:
=
 
× 100
(3600×1000)
Equation 12
Using this method to find P assumes that each button touch occurs after any Buzzer Signal Output or Button Touch
LED Effects have finished and no other button is touched. If this is not the case, using this value for P will result in a
higher power consumption calculation than the actual value.
5.2.6 Average Use Current (IAVE_U)
_ = (
100−
100
× _ ) + (

100
× _ )
Equation 13
Where:
P = percentage of active time
IAVG_NT = average current in the NO TOUCH state
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Low-Power Design Considerations
IAVG_T = average current in the TOUCH state
5.2.7 Average Current (IAVE)
 = [_ × (

 +
)] + 0.1 µ
Equation 14
Where:
TSA = time device is not in deep sleep mode
TDS = time device is in deep sleep mode
5.2.8 Average Power (PAVE)
 =  × 
Equation 15
Where:
IAVE = average current
VDD = supply voltage
5.2.9 Example Calculation
As an example of how to calculate average power, consider a CapSense user interface with eight well-designed
buttons and the following parameters:
 CP for all eight buttons is between 10—20 pF
 Sensitivity of each button is high
 Design is response time-optimized
 Noise Immunity is “Normal”
 Button scan rate offset is set to 506 ms
 Standby Mode LED Brightness is disabled
 Typical current consumption values measured
The button scan rate constant can be obtained from Table 3-5:
 = 35 
The button scan rate is calculated using Equation 5:
 = 35 + 506 = 541 
The scan time can be calculated using Equation 7, with the button sensitivity constant obtained from Table 5-1, and
the typical value for firmware execution time from Table 5-2.
 = [0.375 × (8 × 2)] + 6.00 = 12.0 
The average current in NO TOUCH state is calculated as follows using Equation 8 and the maximum values for I SLEEP
and IACTIVE from Table 5-2.
_ = (
541−12
541
× 9.52 µ) + (
12
541
× 3.4 ) = 84.7 µ
The average current in TOUCH state is calculated as follows using Equation 9:
_ = (
35−12
35
× 9.52 µ) + (
12
35
× 3.4 ) = 1172 µ
To calculate the active time using Equation 10, assume that a button is touched once a minute (60 button touches per
hour). On average, button touch time is 1000 ms, Button Touch LED Effects time is 3000 ms, and there are no buzzer
outputs.
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Low-Power Design Considerations
  = 3000 × 60 = 180 
The percentage of active time is calculated using Equation 11:
=
180
×
3600
100 = 5%
The average current consumption of the design is calculated as follows using Equation 12:
100 − 5
5
_ = (
× 84.7 µ) + (
× 1172 µ) = 139.1 µ
100
100
Assuming this design does not utilize deep sleep mode and that it operates at 1.71 V, the average power is
calculated as follows using Equation 14:
 = 1.71 × 139.1 µ = 237.8 µ
5.3 Sleep Modes
Cypress’s CY8CMBR2110 can be configured to operate in either low-power sleep mode or deep sleep mode. These
modes reduce the power consumption of the device.
5.3.1 Low-Power Sleep Mode
The behavior of the CY8CMBR2110 controller in Low-Power Sleep mode is described in Figure 5-1.
Figure 5-1. Low-Power Sleep Mode
Scan all CS inputs using Button
Scan Rate constant
No
CS inputs remain in
NO TOUCH state
for 15 seconds?
Yes
Yes
Scan all CS inputs using Button
Scan Rate constant
No
Any CS input
transitions to
TOUCH state?
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Low-Power Design Considerations
5.3.2 Deep Sleep Mode
If you use the CY8CMBR2110 in a system with a host processor, the Attention/Sleep line can operate the device in
Deep Sleep mode. For CY8CMBR2110 to go into Deep Sleep mode, follow these steps:
1.
Pull the Attention/Sleep line low
2.
Set the “Deep Sleep” bit in Host_Mode register (in Operating Mode) to 1
3.
Wait for 50 ms
4.
Pull the Attention/Sleep pin high
All communication is suspended. In Deep Sleep mode, the device consumes ~0.1-µA. After the device enters Deep
Sleep mode, the Deep Sleep bit is automatically cleared. To wake up, the Attention/Sleep line is pulled low by the
host. After it wakes up, the CY8CMBR2110 goes into active mode. The host processor can then pull the
Attention/Sleep pin high to put the device into Low-Power Sleep mode. After waking up from Deep Sleep mode, the
device takes some time before the button scanning restarts, this period is called re-initialization. During this time, any
button touch is not reported. Re-initialization takes 20 ms if Noise Immunity is "Normal" or 50 ms if Noise Immunity is
"High".
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6. Resources
6.1 Website
Visit Cypress’s CapSense Controllers website to access all of the reference material discussed in this section.
Find a variety of technical resources on the CY8CMBR2110 web page.
6.2 Datasheet
The datasheet for the CapSense CY8CMBR2110 device is available at www.cypress.com.
 CY8CMBR2110
6.3 Design Toolbox
The interactive Design Toolbox will enable you to design a robust and reliable CY8CMBR2110 CapSense solution.
6.4 EZ-Click™ Customizer Tool
The interactive EZ-Click Customizer Tool will help you configure your CY8CMBR2110 CapSense solution.
6.5 Design Support
To ensure the success of your CapSense solutions, Cypress has a variety of design support channels.
 Knowledge-Based Articles –Browse technical articles by product family or search on CapSense topics.
 CapSense Application Notes – Peruse a wide variety of application notes built on information presented in this
document.
 White Papers – Learn about advanced capacitive touch interface topics.
 Cypress Developer Community – Connect with the Cypress technical community and exchange information.
 CapSense Product Selector Guide – See the complete CapSense product line.
 Video Library –Get up to speed quickly with tutorial videos
 Quality & Reliability – Cypress is committed to customer satisfaction. At our Quality website, find reliability and
product qualification reports.
 Technical Support – World-class technical support is available online.
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7. Appendix
7.1 Schematic Example
7.1.1 Schematic 1: Ten Buttons with Ten GPOs
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Appendix
In Schematic 1: Ten Buttons with Ten GPOs, CY8CMBR2110 is configured as follows:
 CS0—CS9 pins: 560 Ω to CapSense buttons

Ten CapSense buttons (CS0—CS9)
 GPO0—GPO9 pins: LED and 5 kΩ to VDD

CapSense buttons driving ten LEDs (GPO0—GPO9)
 CMOD pin: 2.2 nF to Ground

Modulating capacitor
 XRES pin: Floating

For external reset
 BuzzerOut0 pin: To buzzer


AC buzzer (1-pin)
Buzzer second pin to Ground
 BuzzerOut1 pin: LED and 5 kΩ to Ground

Used as Host Controlled GPO
 HostControlGPO0, HostControlGPO1: LED and 5 kΩ to Ground

Two Host Controlled GPOs
 I2C_SDA, I2C_SCL pins: 330 Ω to I2C Header

For I2C communication
 Attention/Sleep pin: To Host

For controlling I2C communication, power consumption, and device operating mode
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Appendix
7.1.2 Schematic 2: Eight Buttons with Analog Voltage Output
In Schematic 2: Eight Buttons with Analog Voltage Output, CY8CMBR2110 is configured as follows:
 CS0—CS7 pins: 560 Ω to CapSense buttons; CS8, CS9 pins: Ground

Eight CapSense buttons (CS0 – CS7)

CS8 and CS9 buttons not used in design
 GPO0—GPO7 pins: To external resistive network

Eight GPOs (GPO0 – GPO7) used for Analog Voltage Output

GPO8 and GPO9 not used in design
 CMOD pin: 2.2 nF to Ground

Modulating capacitor
 XRES pin: Floating

For external reset
 BuzzerOut0, BuzzerOut1 pins: To AC Buzzer

AC 2-pin Buzzer
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 HostControlGPO0, HostControlGPO1 pins: LED and 5 kΩ to Ground

Two Host Controlled GPOs
 I2C_SDA, I2C_SCL pins: 330 Ω to I2C Header

For I2C communication
 Attention/Sleep pin: To Host

For controlling I2C communication, power consumption, and device operating mode
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7.2 APIs for CY8CMBR2110 Configuration
The following table lists 72 high-level APIs and 3 low-level APIs, which will be used at host processor (I2C master) to
configure CY8CMBR2110 (I2C slave) through I2C interface. These high-level APIs are independent of platforms and
can be used on any host processor. The appropriate inputs are defined as macros for many high-level APIs in
inputs.h.
Low-level APIs are platform dependent and used in the host processor to enable physical I2C communication with the
device. These low-level APIs are developed for the PSoC 1 host device; therefore, you may need to modify the lowlevel API code depending on your host processor. The sample project created using these APIs is explained in
section 3.4.2.9.
7.2.1 High-Level APIs
Prototype
Description
1
void MBR_Initialization(void);
Initializes global variables used by the high-level APIs. You must call this API first before calling any
other API.
Parameters
None
Return
None
Example
MBR_Initialization();
Prototype
void MBR_SetCustomData(BYTE bCustomData);
Description
Writes the data given by the user to the custom data storage register in Device Configuration mode. User
should call MBR_SaveSettingsToFlash API to store the data permanently.
Parameters
Name
Description
Possible values
bCustomData
Date to be written in Custom register
0 to 255
2
Return
None
MBR_SetCustomData(200);
Example
Value 200 will be stored in Custom Data Storage registers.
3
4
5
6
Prototype
void MBR_IssueSWReset(void);
Description
Issues software reset to the CY8CMBR2110 device. Refer to Software Reset
Parameters
None
Return
None
Example
MBR_IssueSWReset();
Prototype
WORD MBR_ReadFlashChecksum(void);
Description
Reads the checksum stored in the flash of CY8CMBR2110 device.
Parameters
None
Return
Flash checksum of CY8CMBR2110 device
Example
MBR_ReadFlashChecksum();
Prototype
WORD MBR_ReadRAMChecksum(void);
Description
Reads the checksum stored in the RAM of CY8CMBR2110 device.
Parameters
None
Return
RAM checksum of CY8CMBR2110 device
Example
MBR_ReadRAMChecksum();
Prototype
void MBR_SetChecksum(void);
Description
Writes the checksum calculated by the host in to the CY8CMBR2110 device. Host itself calculates the
check sum of the configurations
Parameters
None
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Return
None
Example
MBR_SetChecksum();
Prototype
BYTE MBR_ReadChecksumMatch(void);
Description
Checks whether RAM checksum calculated by CY8CMBR2110 device is same as that of the checksum
entered by the Host.
Parameters
None
Return
0 or 1
0 for checksum mismatch
1 for checksum match
Example
MBR_ReadChecksumMatch();
Prototype
BYTE MBR_SaveSettingsToFlash(void);
Description
Saves the current configuration of the CY8CMBR2110 device to flash (refer to the Configuring the
CY8CMBR2110)
Parameters
None
7
8
0 or 1
Return
0 - save to flash is not successful
1 - save to flash is successful
Example
MBR_SaveSettingsToFlash();
Prototype
BYTE MBR_SettingsLoaded(void);
Description
Indicates whether the factory default setting or the user configured setting is loaded
Parameters
None
Return
0 or 1
0 - user configured settings
1 - factory default settings
Example
MBR_SettingsLoaded( );
Prototype
void MBR_LoadFactoryDefaults(void);
Description
Loads the factory default settings configuration in to the RAM of CY8CMBR2110 device.
Parameters
None
Return
None
Example
MBR_LoadFactoryDefaults();
Prototype
void MBR_ReadConfigData(BYTE abConfigData[]);
Description
Loads the LED configuration and device configuration data from the CY8CMBR2110 device.
Parameters
Name
Description
abConfigData
Pointer to 64-byte array to hold all the
configuration data
9
10
11
Possible values
Return
None
Example
MBR_ReadConfigData(abConfigData);
abConfigData is a pointer to the 64-byte array abConfigData[64].The array is updated with all the
configuration data.
Prototype
void MBR_LEDEffectsBreathing(BYTE bGPO, BYTE bBreath);
Description
12
Parameters
Enables or disables the button touch LED effects breathing.
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Name
Description
Possible values
bGPO
GPO number
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bBreath
Enable/disable the breathing effect
0 or 1
0 - disable breathing
1 - enable breathing
Return
None
Example
MBR_LEDEffectsBreathing( GPO4, FEATURE_ENABLE);
GPO4 is a macro with value 4, FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_LEDEffectsRepeatRate(BYTE bGPO, BYTE bRepeatRate,
BYTE bPwrOnOrBtnTch);
Sets the repeat rate of the LED effect for selected GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bRepeatRate
Repeat rate of the LED effect
0 to 7
0 - Repeat rate of 0
1 - Repeat rate of 1
2 - Repeat rate of 2
13
3 - Repeat rate of 4
4 - Repeat rate of 6
5 - Repeat rate of 10
6 - Repeat rate of 15
7 - Repeat rate of 20
bPwrOnOrBtnTch
Power on or button touch LED effects
1 or 2
1 - power on LED
2 - Button touch LED
Return
None
Example
MBR_LEDEffectsRepeatRate(GPO1,REPEAT_RATE_20,POWER_ON_LED_EFFECTS);
GPO1, REPEAT_RATE_20,POWER_ON_LED_EFFECTS are macros with values 1, 7, 1 (inputs.h).
Prototype
void MBR_LEDEffectsLowBrightness(BYTE bGPO, BYTE bLowBright,
BYTE bPwrOnOrBtnTch);
Sets the LED low brightness for the GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bLowBright
Low brightness level as per register map
0 to 7
0 - Low brightness 0%
14
1 - Low brightness 10%
……………………………
…………………………...
7 – Low brightness 100%
bPwrOnOrBtnTch
Power on or button touch LED effects
1 or 2
1 - power on LED
2 - Button touch LED
Return
None
Example
MBR_LEDEffectsLowBrightness(GPO2, LOW_BRIGHT_80, BTN_TOUCH_LED_EFFECTS);
GPO2, LOW_BRIGHT_80, BTN_TOUCH_LED_EFFECTS are macros with values 2 ,6, 2 (inputs.h).
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Prototype
void MBR_LEDEffectsHighBrightness(BYTE bGPO, BYTE bHighBright, BYTE bPwrOnOrBtnTch);
Sets the LED high brightness for the GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bHighBright
High brightness level as per the register
map
0 to 7
0 - High brightness 100%
1 - High brightness 90%
15
……………………………
…………………………...
7 - High brightness 0%
bPwrOnOrBtnTch
Power on or button touch LED effects
1 or 2
1 - power on LED
2 - Button touch LED
Return
None
Example
MBR_LEDEffectsHighBrightness(GPO9, HIGH_BRIGHT_50, BTN_TOUCH_LED_EFFECTS);
GPO9, HIGH_BRIGHT_50, BTN_TOUCH_LED_EFFECTS are macros with values 9 ,4, 2 (inputs.h).
Prototype
void MBR_LEDEffectsLowTime(BYTE bGPO, BYTE bLowTime,
BYTE bPwrOnOrBtnTch);
Sets the LED low time for GPOs.
Description
Note For LED effects ,GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bLowTime
Global period register map to the get the
low time value
0 to 1
16
bPwrOnOrBtnTch
Power on or button touch LED effects
0 - GLOBAL_PERIOD_1
1 - GLOBAL_PERIOD_2
1 or 2
1 - power on LED
2 - Button touch LED
Return
None
Example
MBR_LEDEffectsLowTime(GPO6, GLOBAL_PERIOD_1, BTN_TOUCH_LED_EFFECTS);
GPO6, GLOBAL_PERIOD_1, BTN_TOUCH_LED_EFFECTS are macros with values 6, 0, 2 (inputs.h).
Prototype
void MBR_LEDEffectsHighTime(BYTE bGPO, BYTE bHighTime,
BYTE bPwrOnOrBtnTch);
Set the LED high time for the GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bHighTime
Global period register map to the get the
high time value
0 to 1
17
bPwrOnOrBtnTch
Return
Power on or button touch LED effects
0 - GLOBAL_PERIOD_1
1 - GLOBAL_PERIOD_2
1 or 2
1 - power on LED
2 - Button touch LED
None
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Example
MBR_LEDEffectsHighTime(GPO5, GLOBAL_PERIOD_2, BTN_TOUCH_LED_EFFECTS);
GPO5, GLOBAL_PERIOD_2, BTN_TOUCH_LED_EFFECTS are macros with values 5, 1, 2 (inputs.h).
Prototype
void MBR_LEDEffectsRampDown(BYTE bGPO, BYTE bRampDown,
BYTE bPwrOnOrBtnTch);
Sets the ramp down time for the GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bRampDown
Global period register map to the get the
ramp down time value
0 to 3
Power on or button touch LED effects
1 or 2
1 - power on LED
2 - Button touch LED
18
bPwrOnOrBtnTch
0 - GLOBAL_PERIOD_1
1 - GLOBAL_PERIOD_2
2 - GLOBAL_PERIOD_3
3 - GLOBAL_PERIOD_4
Return
None
Example
MBR_LEDEffectsRampDown(GPO8, GLOBAL_PERIOD_1, POWER_ON_LED_EFFECTS);
GPO8, GLOBAL_PERIOD_1, POWER_ON_LED_EFFECTS are macros with values 8, 0, 1 (inputs.h).
Prototype
void MBR_LEDEffectsRampUp(BYTE bGPO, BYTE bRampUp, BYTE bPwrOnOrBtnTch);
Sets the ramp up time for the GPOs.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789 Configuring one GPO
in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
bRampUp
Global period register map to the get the
ramp up time value
0 to 3
Power on or button touch LED effects
1 or 2
1 - power on LED
2 - Button touch LED
19
bPwrOnOrBtnTch
Return
None
Example
MBR_LEDEffectsRampUp(GPO8, GLOBAL_PERIOD_1, POWER_ON_LED_EFFECTS)
GPO8, GLOBAL_PERIOD_1, POWER_ON_LED_EFFECTS are macros with values 8, 0, 1 (inputs.h).
Prototype
void MBR_PowerONLEDEffectSeq(BYTE bPwrOnSeq);
Description
Sets the power-on LED Effects sequence (concurrent or sequential) .Make sure that you enabled the
power on LED effects before calling this API.
Parameters
Name
Description
Possible values
bPwrOnSeq
Type of Power on LED effect sequence
0 or 1
0 - concurrent
1 - sequential
20
21
0 - GLOBAL_PERIOD_1
1 - GLOBAL_PERIOD_2
2 - GLOBAL_PERIOD_3
3 - GLOBAL_PERIOD_4
Return
None
Example
MBR_PowerONLEDEffectSeq(POWER_ON_SEQUENTIAL);
POWER_ON_SEQUENTIAL is a macro with value 1 (inputs.h).
Prototype
void MBR_PowerONLEDEffects(BYTE bEnable);
Description
Enables or disables power on LED effects.
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Parameters
Name
Description
Possible values
bEnable
Enable or disable the effect
0 to 1
0 - disable the effect
1 - enable the effect
Return
None
Example
MBR_PowerONLEDEffects(FEATURE_ENABLE);
FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_ButtonLEDEffects(BYTE bEnable);
Description
Enables or disables the Button Touch LED Effects
Parameters
Name
Description
Possible values
bEnable
Enable or disable the effect
0 to 1
0 - disable the effect
1 - enable the effect
22
Return
None
Example
MBR_ButtonLEDEffects(FEATURE_DISABLE);
FEATURE_DISABLE is a macro with a value 0. (inputs.h)
Prototype
void MBR_StandbyModeLEDBrightness(BYTE bLEDBrightness);
Description
Sets the standby mode LED Brightness level.
Parameters
Name
Description
Possible values
bLEDBrightness
Standby mode brightness level as per the
register map
0 to 3
0 - 0% brightness
1 - 20% brightness
2 - 30% brightness
3 - 50% brightness
23
Return
None
Example
MBR_StandbyModeLEDBrightness(STDBY_LED_50) ;
STDBY_LED_50 is a macro with value 3 (inputs.h)
Prototype
void MBR_LEDEffectLastButton(BYTE bEnable);
Description
Enables or disables LED effects on last button touch feature.
Parameters
Name
Description
Possible values
BYTE bEnable
Enable or disable the effect
0 or 1
0 - disable the effect
1 - enable the effect
24
Return
None
Example
MBR_LEDEffectLastButton(FEATURE_DISABLE);
FEATURE_DISABLE is a macro with value 0 (inputs.h)
Prototype
void MBR_SetGlobalPeriod(BYTE bPeriodReg, WORD wPeriodValue);
Description
Sets the period value in the global period register
Parameters
Name
Description
Possible values
bPeriodReg
Global period register map
0 to 3
0 - GLOBAL_PERIOD_1
1 - GLOBAL_PERIOD_2
2 - GLOBAL_PERIOD_3
3 - GLOBAL_PERIOD_4
25
wPeriodValue
Return
Global period value in (ms)
0 to 1600
None
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Example
MBR_SetGlobalPeriod(GLOBAL_PERIOD_1,600)
GLOBAL_PERIOD_1 is a macro with value 0 (inputs.h).
Prototype
void MBR_SetAllGlobalPeriods(WORD awPeriodValue[]);
Description
Sets the period values of all the global period registers.
Parameters
Name
Description
Possible values
awPeriodValue
Pointer to a 4-word array holding the
period values in (ms)
0 to 1600
26
Return
None
Example
MBR_SetAllGlobalPeriods(wTestBuffer);
wTestBuffe is the base pointer of the 4-word array wTestBuffer[4].
Prototype
void MBR_SetAllLEDParameters(BYTE bGPO, BYTE abParam[]);
Sets all the LED effects parameters for any GPO.
Description
Note For LED effects, GPOs are grouped as: GPO0, GPO123, GPO456, GPO789. Configuring one
GPO in a group also configures the other GPOs in that group.
Parameters
Name
Description
Possible values
bGPO
GPO number
0 to 9
awPeriodValue
Pointer to 9 byte array
holding configuring
parameters
27
28
29
30
byte[0] - Power On or Button Touch effects
byte[1] - High brightness level
byte[2] - Low brightness level
byte[3] - Ramp up time mapping to global period
registers
byte[4] - Ramp down time mapping to global period
registers
byte[5] - High time mapping to global period
registers
byte[6] - Low time mapping to global period
registers
byte[7] - Repeat rate
byte[8] - Breathing effect enable/disable
Return
None
Example
MBR_SetAllLEDParameters(GPO2, bconfig);
bconfig is a pointer of the 9-byte array bconfig[9].
Prototype
BYTE MBR_ReadDeviceID(void);
Description
Reads the CY8CMBR2110 device ID.
Parameters
None
Return
Device ID of CY8CMBR2110.The ID is “0xA1”.
Example
MBR_ReadDeviceID();
Prototype
BYTE MBR_ReadFWRevision(void);
Description
Reads the slave device firmware revision.
Parameters
None
Return
Device firmware revision
Example
MBR_ReadFWRevision();
Prototype
void MBR_SetDebugSensorNumber(BYTE bSensor);
Description
Sets the sensor number for which the debug data has to be sent.
Parameters
Name
Description
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Appendix
bSensor
Sensor number
0 to 9
Return
None
Example
MBR_SetDebugSensorNumber(CS0);
CS0 is a macro with value 0 (inputs.h).
Prototype
void MBR_SetDebugDataParameter(BYTE bParameter);
Description
Set the type of parameter to be sent in debug data out.
Parameters
Name
Description
Possible values
bParameter
Type of parameter
0 to 4
0 - CP
1 - Raw counts
2 - Difference counts
3 - Raw counts ,baseline
4 - All parameters(CP, Raw
count, difference count,
base line, SNR)
31
Return
None
Example
MBR_SetDebugDataParameter(DEBUG_PARAM_CP);
DEBUG_PARAM_CP is a macro with value 0 (inputs.h).
Prototype
void MBR_ReadDebugData(BYTE abDebugData[]);
Description
Reads the debug data of the selected parameter from the debug data register map
Parameters
Name
Description
abDebugData
Pointer to 25-byte array to hold the
debug data
32
Possible values
Return
None
Example
MBR_ReadDebugData(bgetdata);
bgetdata is a pointer to the 25-byte array bgetdata[25]. The array is updated with the debug data.
Prototype
void MBR_SetBuzzer(BYTE bEnable);
Description
Enables or disables the audio feedback (buzzer).
Parameters
Name
Description
Possible values
bEnable
Enable or disable buzzer
0 or 1
0 – enable
1 – disable
33
Return
None
Example
MBR_SetBuzzer(FEATURE_ENABLE)
FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_SetBuzzerPins(BYTE bBuzzerPins);
Description
Sets the number of pins for the buzzer.
Parameters
Name
Description
Possible values
bBuzzerPins
Number of buzzer output pins
0 or 1
0 - 1 pin buzzer
1 - 2 pin buzzer
34
Return
None
Example
MBR_SetBuzzerPins(BUZZER_AC_2_PIN);
BUZZER_AC_2_PIN is a macro with value 1 (inputs.h).
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Prototype
void MBR_SetBuzzerIdleState(BYTE bIdleState);
Description
Sets the idle state of the buzzer pins.
Parameters
Name
Description
Possible values
bIdleState
Buzzer idle state
0 or 1
0 - LOW
1 - HIGH
35
Return
None
Example
MBR_SetBuzzerIdleState(BUZZER_IDLE_HIGH);
BUZZER_IDLE_HIGH is a macro with value 1 (inputs.h)
Prototype
void MBR_SetBuzzerFrequency(BYTE bFrequency);
Description
Sets the output frequency for the buzzer output.
Parameters
Name
Description
Possible values
bFrequency
Buzzer output frequency
1 to 7
1 - 4000 Hz
2 - 2670 Hz
3 - 2000 Hz
4 - 1600 Hz
5 - 1330 Hz
6 - 1140 Hz
7 - 1000 Hz
36
Return
None
Example
MBR_SetBuzzerFrequency (BUZZER_FREQ_1000);
BUZZER_FREQ_1000 is a macro with value 7 (inputs.h).
Prototype
void MBR_SetBuzzerOutputDuration(WORD wDuration);
Description
Sets the duration of the buzzer output.
Parameters
Name
Description
Possible values
wDuration
Buzzer output duration in millisecond
(ms)
(0 to 127) * Button Scan
Rate
37
Return
None
Example
MBR_SetBuzzerOutputDuration(1000);
Prototype
void MBR_SetAllBuzzerParameters(BYTE bEnable, BYTE bParameters[],
WORD wOutputDuration);
Description
Sets all the buzzer parameters of the CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bEnable
Enable or disable buzzer
0 or 1
0 - disable
1 - enable
bParameters
Pointer to the 3-byte array holding the
required inputs
Byte [0] – number of buzzer
pins
Byte [1] – buzzer idle state
Byte [2] – buzzer output
frequency
wOutputDuration
Duration of buzzer output in ms
(0 to 127 ) * Button Scan
Rate
38
Return
None
Example
MBR_SetAllBuzzerParameters(FEATURE_ENABLE , bbuzzconfig ,1000 );
FEATURE_ENABLE is a macro with value 1 (inputs.h), bbuzzconfig is a pointer to a 3-byte array
containing buzzer pins, idle state, and frequency details (1000 is the buzzer duration).
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Prototype
void MBR_SetI2CSlaveAddress (BYTE bNewSlaveAddress);
Description
Sets the I2C address of the CY8CMBR2110 device. The default address is ‘37h’.
Parameters
Name
Description
Possible values
bNewSlaveAddress
New address value to the device
0x00 to 0x7F
39
Return
None
Example
MBR_SetI2CSlaveAddress(50);
Prototype
void MBR_SetAdaptiveThreshold(BYTE bSetRest);
Description
Enables or disables automatic threshold feature of the CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bSetRest
Enable or disable automatic threshold
feature
0 or 1
0 – to disable
1 – to enable
40
Return
None
Example
MBR_SetAdaptiveThreshold(FEATURE_ENABLE);
FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_SetSensitivity(BYTE bButtonNumber, BYTE bButtonSensitivityLevel);
Description
Sets the sensitivity value for a button.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
bButtonSensitivityLevel
Sensitivity level of the button
1 to 3
1 – high sensitivity
2 – medium sensitivity
3 – low sensitivity
41
Return
None
Example
MBR_SetSensitivity (CS9, SENSITIVITY_MEDIUM);
CS9 and SENSITIVITY_MEDIUM are macros with values 9 and 2 (inputs .h).
Prototype
void MBR_SetSensitivityAll(BYTE bsensitivity[]);
Description
Sets the sensitivity value of all the buttons.
Parameters
Name
Description
Possible values
bsensitivity
Pointer to the 10-byte array holding the
sensitivity level for all the buttons
1 to 3
1 – high sensitivity
2 – medium sensitivity
3 – low sensitivity
42
Return
None
Example
test_MBR_SetSensitivityAll(bBuffer);
bBuffer is a pointer to the 10-byte array bBuffer[10] that holds the sensitivity values for all the buttons
(the first byte corresponds to the button number 0,……..tenth byte corresponds to button 9).
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Prototype
void MBR_SetDebounce(BYTE bButtonNumber, BYTE bDebouncevalue);
Description
Sets the debounce level of buttons. Button numbers 1 to 9 are configured with the same value. They
cannot be configured individually.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 1
0 – for button number 0
1 – for button number (1-9)
bDebouncevalue
Debounce value for the buttons
1 to 255
43
Return
None
Example
MBR_SetDebounce(DEBOUNCE_FOR_CS0, 200);
DEBOUNCE _FOR_CS0 is a macro with value 0 (inputs.h).
Prototype
void MBR_SetFingerThreshold(BYTE bButtonNumber, BYTE bFingerthreshold);
Description
Sets the finger threshold level for a button.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
bFingerthreshold
Finger threshold level
0 to 15
44
Return
None
Example
MBR_SetFingerThreshold(CS3, FINGER_THRESHOLD_180);
CS3 and FINGER_THRESHOLD_180 are macros with values 3 and 10 (inputs.h).
Prototype
void MBR_SetFingerThresholdAll(BYTE bFingerthreshold[]);
Description
Sets the finger threshold level for all the sensors.
Parameters
Name
Description
Possible values
bFingerthreshold
Pointer to the 10-byte array holding the
finger threshold values
0 to 15
45
Return
None
Example
MBR_SetFingerThresholdAll(Buffer);
Buffer is a pointer to the 10-byte array Buffer[10] holding the finger threshold level for all the buttons. The
first byte corresponds to the button number 0,……..tenth byte corresponds to button 9).
Prototype
BYTE MBR_ReadSensorStatus(BYTE bButtonNumber);
Description
Reads the current status of a button (to check current state of button touch).
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
46
Return
0 or 1
0 – button is not pressed (OFF)
1 – button is pressed (ON)
Example
MBR_ReadSensorStatus(CS5);
CS5 is a macro with value 5 (inputs.h).
Prototype
WORD MBR_ReadSensorStatusAll(void);
Description
Reads the current status of all the buttons.
Return
Two bytes with the current status of all the sensors.
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9
47
For example, 0x0301 indicates buttons 0, 8, 9 are touched (ON) and rest of the buttons are not touched
(OFF).
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Appendix
Example
MBR_ReadSensorStatusAll();
Prototype
WORD MBR_ReadLatchStatusAll(void);
Description
Reads the latched status of all the sensors.
Parameters
None
Return
Two bytes with the current latched status of all the sensors.
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9
48
For example, 0x0301 indicates buttons 0, 8, 9 were touched (ON) and rest of the buttons were not
touched (OFF) before the current I2C read.
49
Example
MBR_ReadLatchStatusAll();
Prototype
void MBR_EnterDeepSleep(void);
Description
Sets the Deep sleep bit as 1 in operating mode register so device will enter into deep sleep mode. Follow
the procedures in Deep Sleep Mode to change the mode to deep sleep mode.
Parameters
None
Return
None
Example
MBR_EnterDeepSleep();
Prototype
void MBR_SetPowerOptimization(BYTE bOptimization);
Description
Sets the power consumption optimized or response time optimized design for the CY8CMBR2110
device.
Parameters
Name
Description
Possible values
bOptimization
Enables power consumption or response
time optimization
0 or 1
0 - response time optimization
1 - power consumption
optimization
50
Return
None
Example
MBR_SetPowerOptimization(PWR_CONS_OPT);
PWR_CONS_OPT is a macro with value 1 (inputs.h)
Prototype
void MBR_SetScanRate(BYTE bSetscanvalue);
Description
Sets the scan rate of the CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bSetscanvalue
Scan rate values as per the
register map
0 to 31
51
0 – 25 ms
31- 561 ms
52
Return
None
Example
MBR_SetScanRate(30);
Prototype
void MBR_SetHGPOValue(BYTE bHGPO_Number, BYTE bDriveLogic);
Description
Sets the drive logic of a HGPO.
Parameters
Name
Description
Possible values
bHGPO_Number
Host controlled GPO
(HGPO) number
0 to 3
0 - HGPO0
1 - HGPO1
2 - HGPO2
3 - HGPO3
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Appendix
bDriveLogic
0 or 1
1 - HIGH
0 - LOW
Return
None
Example
MBR_SetHGPOValue(HOSTGPO_3, HOSTGPO_HIGH);
HOSTGPO_3 and HOSTGPO_HIGH are macros with values 3 and 1 (inputs.h).
Prototype
void MBR_SetAllHGPOValue(BYTE bdriveGP0, BYTE bdriveGP1, BYTE bdriveGP2,
BYTE bdriveGP3);
Description
Sets the drive logic of all HGPOs.
Parameters
Name
Description
Possible values
bdriveGP0
Drive logic of HGPO0
0 or 1
bdriveGP1
Drive logic of HGPO1
0 or 1
bdriveGP2
Drive logic of HGPO2
0 or 1
bdriveGP3
Drive logic of HGPO3
0 or 1
53
Return
None
Example
void MBR_SetAllHGPOValue(HOSTGPO_HIGH, HOSTGPO_HIGH, HOSTGPO_LOW,
HOSTGPO_LOW);
HOSTGPO_HIGH, HOSTGPO_HIGH, HOSTGPO_LOW, and HOSTGPO_LOW are macros with the
values 1, 1, 0, 0 (inputs.h).
Prototype
void MBR_AnalogOutput(BYTE bSet_Reset)
Description
Enables or disables analog output voltage feature of the CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bSet_Reset
Set or resets analog output voltage feature
0 or 1
54
Return
None
Example
MBR_AnalogOutput(FEATURE_ENABLE);
FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_SetToggle (BYTE bButtonNumber, BYTE fSet_Reset);
Description
Enables or disables the toggle feature for a button of the CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
fSet_Reset
Enable or disable toggle
0 or 1
0 - disable
1 - enable
55
56
Drive logic level
Return
None
Example
MBR_SetToggle(CS0,FEATURE_ENABLE);
FEATURE_ENABLE is a macro with value 1 (inputs.h).
Prototype
void MBR_SetToggleAll(BYTE afSet_Reset[]);
Description
Enables or disables the toggle feature for all the buttons
Parameters
Name
Description
Possible values
afSet_Reset
Pointer to 2-byte array
holding values
Byte[1] - 0x00 to 0xFF
Byte[2] - 0x00 to 0x03
Return
None.
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Appendix
Example
MBR_SetToggleAll(Buffer);
Buffer is a pointer to the 2-byte array Buffer
Buffer[1] holds the values for buttons 0 to 7
The first two bits of Buffer[2] hold the values for buttons 8 and 9.
For example, Buffer[1] = 0xFF enables toggle for buttons 0 to 7, and Buffer[2] = 0x01 enables toggle for
button 8 and disables toggle for button 9.
Prototype
void MBR_LEDONTime(BYTE bSet_Reset);
Description
Enables or disables LED on time feature of CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bSet_Reset
Enable or disable the
feature
0 or 1
0 - disable
1- enable
57
58
Return
None
Example
MBR_LEDONTime(FEATURE_DISABLE);
FEATURE_DIASBLE is a macro with value 0 (inputs.h).
Prototype
BYTE MBR_ReadValidSensors(void);
Description
Reads the valid sensor/button count
Buttons may be disabled due to short to VDD, short to GND, improper CP value, and improper CMOD
value.
Parameters
None
Return
One byte of data indicating the valid sensor count
A return value of 8 indicates eight buttons are valid and two buttons are disabled.
Example
MBR_ReadValidSensors();
Prototype
BYTE MBR_ReadFMEAGround(BYTE bButtonNumber);
Description
Reads the system diagnostics data of one button for short to ground (checks if a button is shorted to
ground).
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
59
Return
0 or 1
0 - button is not shorted to ground
1 - button is shorted to ground
Example
MBR_ReadFMEAGround(CS9);
CS9 is a macro with value 9 (inputs.h).
Prototype
WORD MBR_ReadFMEAGroundAll(void);
Description
Reads the system diagnostics data of all the buttons for short to ground.
Parameters
None
Return
Two bytes to indicate which buttons are shorted to ground
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9
60
For example, 0x02F1 indicates buttons 0,4,5,6,7,9 are shorted to ground
61
Example
MBR_ReadFMEAGroundAll();
Prototype
BYTE MBR_ReadFMEAVDD(BYTE bButtonNumber);
Description
Reads the system diagnostics data of one button for short to VDD (checks if a button is shorted to VDD).
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
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Appendix
Return
0 or 1
0 - button is not shorted to VDD
1 - button is shorted to VDD
Example
MBR_ReadFMEAVDD(CS8);
CS8 is a macro with value 8 (inputs.h).
Prototype
WORD MBR_ReadFMEAVDDAll(void);
Description
Reads the system diagnostics data of all the buttons for short to VDD.
Parameters
None
Return
Two bytes to indicate which buttons are shorted to VDD.
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9.
62
For example, 0x02F1 indicates buttons 0,4,5,6,7,9 are shorted to VDD.
Example
MBR_ReadFMEAVDDAll();
Prototype
WORD MBR_ReadFMEASnsToSnsAll(void);
Description
Reads the system diagnostics data of all the buttons for button to button short.
Parameters
None
Return
Two bytes to indicate which buttons are shorted to another button.
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9.
63
For example, 0x02F1 indicates buttons 0,4,5,6,7,9 are shorted to another button.
Example
MBR_ReadFMEASnsToSnsAll();
Prototype
BYTE MBR_ReadFMEASensorCP(BYTE bButtonNumber);
Description
Read the system diagnostics data of a button for high Cp value.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
64
Return
0 or 1
0 - Cp of the button is proper (Cp < 40 pF )
1 - Cp of the button is high (Cp > 40 pF)
Example
MBR_ReadFMEASensorCP(CS0);
CS0 is a macro with value 0 (inputs.h).
Prototype
WORD MBR_ReadFMEASensorCpAll(void);
Description
Reads the system diagnostics data of all the buttons for high CP values.
Parameters
None
Return
Two bytes to indicate which buttons have a high Cp value.
LSB is buttons 0 to 7
First two bits of MSB are buttons 8 and 9.
65
For example, 0x02F1 indicates buttons 0,4,5,6,7,9 have Cp > 40 pF.
66
Example
MBR_ReadFMEASensorCpAll();
Prototype
BYTE MBR_ReadFMEACMOD(void);
Description
Reads the system diagnostics of CMOD (checks the CMOD capacitance value).
Parameters
None
Return
0 - if CMOD is proper within (1- 4) nF
1 - if COMD is above 4 nF
2 - if CMOD is below 1 nF
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Appendix
Example
MBR_ReadFMEACMOD();
Prototype
BYTE MBR_ReadSensorSNR(BYTE bButtonNumber);
Description
Reads the SNR value of the button.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
67
Return
One byte to indicate the button SNR. SNR value can range from 0 to 15 for a button
Example
MBR_ReadSensorSNR(CS9);
CS9 is a macro with value 9 (inputs.h).
Prototype
void MBR_ReadSensorSNRAll(BYTE bSensor_SNR[TOTAL_BUTTON_COUNT]);
Description
Reads the SNR value of all the buttons
Parameters
Name
Description
bSensor_SNR[TOTAL_BUTTON_COUNT]
Pointer to 10-byte array to
hold the read values from
the device
68
Possible values
Return
None
Example
MBR_ReadSensorSNRAll(buffer);
buffer is a pointer to a 10-byte array that is updated with the SNR values starting from button 0 (The first
byte corresponds to button 0, the second byte corresponds to button 1,…. Tenth byte corresponds to
button 9.).
Prototype
void MBR_SetAutoResetTime(BYTE bSet_time);
Description
Sets the auto reset time of all the buttons.
Parameters
Name
Description
Possible values
bSet_time
Auto reset time value
1 - no limit
2 - 5 sec
3 - 20 sec
69
Return
None
Example
MBR_SetAutoResetTime(AUTO_RESET_20S);
AUTO_RESET_20S is a macro with value 3 (inputs.h).
Prototype
void MBR_SetEMC(BYTE bSet_Reset);
Description
Enables or disable EMC feature in CY8CMBR2110 device.
Parameters
Name
Description
Possible values
bSet_Reset
Enable or disable EMC
0 or 1
0 - disable
1 - enable
70
Return
None
Example
MBR_SetEMC(FEATURE_ENABLE);
FEATURE_ENABLE is a macro with value 1 (inputs.h).
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Appendix
Prototype
void MBR_SetFSS(BYTE bButtonNumber, BYTE fSet_Reset);
Description
Enables or disables the FSS (Flanking Sensor suppression) feature for a button.
Parameters
Name
Description
Possible values
bButtonNumber
Button number
0 to 9
fSet_Reset
Enable or disable feature
0 or 1
0 - disable
1 - enable
71
72
Return
None
Example
MBR_SetFSS( CS0,FEATURE_DISABLE);
CS0 and FEATURE_DISABLE are macros with values 0 and 1 (inputs.h).
Prototype
void MBR_SetFSSAllSensors(BYTE afSet_Reset[])
Description
Enables or disables the FSS (Flanking Sensor suppression) feature for all the buttons.
Parameters
Name
Description
Possible values
afSet_Reset
Pointer to 2-byte array
holding the configuring
values
Byte[1] - 0x00 to 0xFF
Byte[2] - 0x00 to 0x03
Return
None
Example
MBR_SetFSSAllSensors(Buffer);
Buffer is a pointer to 2-byte array Buffer[2].
Buffer[1] holds the values for buttons 0 to 7
The first two bits of Buffer[2] hold the values for buttons 8 and 9
For example: Buffer[1] = 0xFF enables FSS for buttons 0 to 7 , Buffer[2] = 0x01 enables the feature for
button 8, Buffer[2] =0x02 enables the feature for button 9 and disables the feature for button 8.
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Appendix
7.2.2 Low-Level APIs
1
Prototype
Description
void MBR_WriteBytes(BYTE abWriteBuffer[], BYTE bNumberOfBytes)
Write the array of bytes to the CapSense slave device.
Parameters
Name
Return
2
Possible values
2
abWriteBuffer
Pointer to the Host I C buffer array
1 to 31 bytes
bNumberOfBytes
Number of bytes to be written
1 to 31
None
Example
MBR_WriteBytes( abHostI2CBuffer, 3);
Prototype
void MBR_ReadBytes(BYTE abReadBuffer[] , BYTE bNumberOfBytes)
Description
Read the array of bytes from the CapSense slave device.
Parameters
Name
Return
3
Description
Description
Possible values
2
abReadBuffer
Pointer to Host I C buffer array
1 to 32 bytes
bNumberOfBytes
Number of bytes to be read
1 to 32
None
Example
MBR_ReadBytes( bHostI2CBuffer, 6);
Prototype
void MBR_Delay(WORD wDelayTime)
Description
Implements software delay in milliseconds.
Parameters
Name
Description
wDelayTime
Delay time in (ms)
Return
Example
Possible values
None
MBR_Delay(100);
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Glossary
Glossary
AMUXBUS
Analog multiplexer bus available inside PSoC that helps to connect I/O pins with multiple internal analog
signals.
SmartSense™ Auto-Tuning
A CapSense algorithm that automatically sets sensing parameters for optimal performance after the
design phase and continuously compensates for system, manufacturing, and environmental changes.
Baseline
A value resulting from a firmware algorithm that estimates a trend in the Raw Count when there is no
human finger present on the sensor. The Baseline is less sensitive to sudden changes in the Raw Count
and provides a reference point for computing the Difference Count.
Button or Button Widget
A widget with an associated sensor that can report the active or inactive state (that is, only two states) of
the sensor. For example, it can detect the touch or no-touch state of a finger on the sensor.
Difference Count
The difference between Raw Count and Baseline. If the difference is negative, or if it is below Noise
Threshold, the Difference Count is always set to zero.
Capacitive Sensor
A conductor and substrate, such as a copper button on a printed circuit board (PCB), which reacts to a
touch or an approaching object with a change in capacitance.
CapSense®
Cypress’s touch-sensing user interface solution. The industry’s No. 1 solution in sales by 4x over No. 2.
CapSense Mechanical Button Replacement (MBR)
Cypress’s configurable solution to upgrade mechanical buttons to capacitive buttons, requires minimal
engineering effort to configure the sensor parameters and does not require firmware development. These
devices include the CY8CMBR3XXX and CY8CMBR2XXX families.
Centroid or Centroid Position
A number indicating the finger position on a slider within the range given by the Slider Resolution. This
number is calculated by the CapSense centroid calculation algorithm.
Compensation IDAC
A programmable constant current source, which is used by CSD to compensate for excess sensor C P.
This IDAC is not controlled by the Sigma-Delta Modulator in the CSD block unlike the Modulation IDAC.
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Glossary
CSD
CapSense Sigma Delta (CSD) is a Cypress-patented method of performing self-capacitance (also called
self-cap) measurements for capacitive sensing applications.
In CSD mode, the sensing system measures the self-capacitance of an electrode, and a change in the
self-capacitance is detected to identify the presence or absence of a finger.
Debounce
A parameter that defines the number of consecutive scan samples for which the touch should be present
for it to become valid. This parameter helps to reject spurious touch signals.
A finger touch is reported only if the Difference Count is greater than Finger Threshold + Hysteresis for a
consecutive Debounce number of scan samples.
Driven-Shield
A technique used by CSD for enabling liquid tolerance in which the Shield Electrode is driven by a signal
that is equal to the sensor switching signal in phase and amplitude.
Electrode
A conductive material such as a pad or a layer on PCB, ITO, or FPCB. The electrode is connected to a
port pin on a CapSense device and is used as a CapSense sensor or to drive specific signals associated
with CapSense functionality.
Finger Threshold
A parameter used with Hysteresis to determine the state of the sensor. Sensor state is reported ON if the
Difference Count is higher than Finger Threshold + Hysteresis, and it is reported OFF if the Difference
Count is below Finger Threshold – Hysteresis.
Ganged Sensors
The method of connecting multiple sensors together and scanning them as a single sensor. Used for
increasing the sensor area for proximity sensing and to reduce power consumption.
To reduce power when the system is in low-power mode, all the sensors can be ganged together and
scanned as a single sensor taking less time instead of scanning all the sensors individually. When the
user touches any of the sensors, the system can transition into active mode where it scans all the sensors
individually to detect which sensor is activated.
PSoC supports sensor-ganging in firmware, that is, multiple sensors can be connected simultaneously to
AMUXBUS for scanning.
Gesture
Gesture is an action, such as swiping and pinch-zoom, performed by the user. CapSense has a gesture
detection feature that identifies the different gestures based on predefined touch patterns. In the
CapSense component, the Gesture feature is supported only by the Touchpad Widget.
Guard Sensor
Copper trace that surrounds all the sensors on the PCB, similar to a button sensor and is used to detect a
liquid stream. When the Guard Sensor is triggered, firmware can disable scanning of all other sensors to
prevent false touches.
Hatch Fill or Hatch Ground or Hatched Ground
While designing a PCB for capacitive sensing, a grounded copper plane should be placed surrounding
the sensors for good noise immunity. But a solid ground increases the parasitic capacitance of the sensor
which is not desired. Therefore, the ground should be filled in a special hatch pattern. A hatch pattern has
closely-placed, crisscrossed lines looking like a mesh and the line width and the spacing between two
lines determine the fill percentage. In case of liquid tolerance, this hatch fill referred as a shield electrode
is driven with a shield signal instead of ground.
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Glossary
Hysteresis
A parameter used to prevent the sensor status output from random toggling due to system noise, used in
conjunction with the Finger Threshold to determine the sensor state. See Finger Threshold.
IDAC (Current-Output Digital-to-Analog Converter)
Programmable constant current source available inside PSoC, used for CapSense and ADC operations.
Liquid Tolerance
The ability of a capacitive sensing system to work reliably in the presence of liquid droplets, streaming
liquids or mist.
Linear Slider
A widget consisting of more than one sensor arranged in a specific linear fashion to detect the physical
position (in single axis) of a finger.
Low Baseline Reset
A parameter that represents the maximum number of scan samples where the Raw Count is abnormally
below the Negative Noise Threshold. If the Low Baseline Reset value is exceeded, the Baseline is reset
to the current Raw Count.
Manual-Tuning
The manual process of setting (or tuning) the CapSense parameters.
Matrix Buttons
A widget consisting of more than two sensors arranged in a matrix fashion, used to detect the presence
or absence of a human finger (a touch) on the intersections of vertically and horizontally arranged
sensors.
If M is the number of sensors on the horizontal axis and N is the number of sensors on the vertical axis,
the Matrix Buttons Widget can monitor a total of M x N intersections using ONLY M + N port pins.
When using the CSD sensing method (self-capacitance), this Widget can detect a valid touch on only one
intersection position at a time.
Modulation Capacitor (CMOD)
An external capacitor required for the operation of a CSD block in Self-Capacitance sensing mode.
Modulator Clock
A clock source that is used to sample the modulator output from a CSD block during a sensor scan. This
clock is also fed to the Raw Count counter. The scan time (excluding pre and post processing times) is
given
by
(2N – 1)/Modulator Clock Frequency, where N is the Scan Resolution.
Modulation IDAC
Modulation IDAC is a programmable constant current source, whose output is controlled (ON/OFF) by the
sigma-delta modulator output in a CSD block to maintain the AMUXBUS voltage at VREF. The average
current supplied by this IDAC is equal to the average current drawn out by the sensor capacitor.
Mutual-Capacitance
Capacitance associated with an electrode (say TX) with respect to another electrode (say RX) is known
as mutual capacitance.
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Glossary
Negative Noise Threshold
A threshold used to differentiate usual noise from the spurious signals appearing in negative direction.
This parameter is used in conjunction with the Low Baseline Reset parameter.
Baseline is updated to track the change in the Raw Count as long as the Raw Count stays within
Negative Noise Threshold, that is, the difference between Baseline and Raw count (Baseline – Raw
count) is less than Negative Noise Threshold.
Scenarios that may trigger such spurious signals in a negative direction include: a finger on the sensor on
power-up, removal of a metal object placed near the sensor, removing a liquid-tolerant CapSenseenabled product from the water; and other sudden environmental changes.
Noise (CapSense Noise)
The variation in the Raw Count when a sensor is in the OFF state (no touch), measured as peak-to-peak
counts.
Noise Threshold
A parameter used to differentiate signal from noise for a sensor. If Raw Count – Baseline is greater than
Noise Threshold, it indicates a likely valid signal. If the difference is less than Noise Threshold, Raw
Count contains nothing but noise.
Overlay
A non-conductive material, such as plastic and glass, which covers the capacitive sensors and acts as a
touch-surface. The PCB with the sensors is directly placed under the overlay or is connected through
springs. The casing for a product often becomes the overlay.
Parasitic Capacitance (CP)
Parasitic capacitance is the intrinsic capacitance of the sensor electrode contributed by PCB trace,
sensor pad, vias, and air gap. It is unwanted because it reduces the sensitivity of CSD.
Proximity Sensor
A sensor that can detect the presence of nearby objects without any physical contact.
Radial Slider
A widget consisting of more than one sensor arranged in a specific circular fashion to detect the physical
position of a finger.
Raw Count
The unprocessed digital count output of the CapSense hardware block that represents the physical
capacitance of the sensor.
Refresh Interval
The time between two consecutive scans of a sensor.
Scan Resolution
Resolution (in bits) of the Raw Count produced by the CSD block.
Scan Time
Time taken for completing the scan of a sensor.
Self-Capacitance
The capacitance associated with an electrode with respect to circuit ground.
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Glossary
Sensitivity
The change in Raw Count corresponding to the change in sensor capacitance, expressed in counts/pF.
Sensitivity of a sensor is dependent on the board layout, overlay properties, sensing method, and tuning
parameters.
Sense Clock
A clock source used to implement a switched-capacitor front-end for the CSD sensing method.
Sensor
See Capacitive Sensor.
Sensor Auto Reset
A setting to prevent a sensor from reporting false touch status indefinitely due to system failure, or when a
metal object is continuously present near the sensor.
When Sensor Auto Reset is enabled, the Baseline is always updated even if the Difference Count is
greater than the Noise Threshold. This prevents the sensor from reporting the ON status for an indefinite
period of time. When Sensor Auto Reset is disabled, the Baseline is updated only when the Difference
Count is less than the Noise Threshold.
Sensor Ganging
See Ganged Sensors.
Shield Electrode
Copper fill around sensors to prevent false touches due to the presence of water or other liquids. Shield
Electrode is driven by the shield signal output from the CSD block. See Driven-Shield.
Shield Tank Capacitor (CSH)
An optional external capacitor (CSH Tank Capacitor) used to enhance the drive capability of the CSD
shield, when there is a large shield layer with high parasitic capacitance.
Signal (CapSense Signal)
Difference Count is also called Signal. See Difference Count.
Signal-to-Noise Ratio (SNR)
The ratio of the sensor signal, when touched, to the noise signal of an untouched sensor.
Slider Resolution
A parameter indicating the total number of finger positions to be resolved on a slider.
Touchpad
A Widget consisting of multiple sensors arranged in a specific horizontal and vertical fashion to detect the
X and Y position of a touch.
Trackpad
See Touchpad.
Tuning
The process of finding the optimum values for various hardware and software or threshold parameters
required for CapSense operation.
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86
Glossary
VREF
Programmable reference voltage block available inside PSoC used for CapSense and ADC operation.
Widget
A user-interface element in the CapSense component that consists of one sensor or a group of similar
sensors. Button, proximity sensor, linear slider, radial slider, matrix buttons, and touchpad are the
supported widgets.
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Revision History
Document Revision History
Document Title: AN76000 - CY8CMBR2110 CapSense® Design Guide
Document Number: 001-76000
Revision
Issue Date
Origin of
Description of Change
Change
**
08/01/2012
UDYG
New Design Guide
*A
09/10/2012
UDYG
Updated links to external documents
*B
03/14/2013
SEEE
Updated Section 3.4 and added Section 7.2.
*C
08/27/2013
UDYG/ZINE
Updated SmartSense Auto-Tuning features in Chapter 1.
Updated FSS description.
Updated screenshots for Figures 3-28, 3-29, 3-30 and 3-31.
Added Ez-Click Customizer screenshot
*D
01/14/2015
SSHH
*E
01/20/2016
VAIR
Updated references to USB-I2C Bridge
Updated to new template.
Added Glossary.
AN76000 - CY8CMBR2110 CapSense® Design GuideDoc. No. 001-76000 Rev. *E
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