Infineon CY8CKIT-028-SENSE User manual

User guide
Please read the sections “Important notice” and “Warnings” at the end of this document
002-32652 Rev. *C
www.infineon.com
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit
User Guide
About this document
Scope and purpose
This guide helps you to get acquainted with the CY8CKIT-028-SENSE IoT sense expansion kit. Hardware details
of the board and its usage information are provided.
Intended audience
This expansion board is intended for all technical specialists who are familiar with IoT and sensing technologies
and is intended to be used under laboratory conditions.
Expansion Board
This board is to be used during the design-in process for interfacing and evaluating sensor features, and for
checking datasheet specifications.
Note: PCB and auxiliary circuits are NOT optimized for final customer design.
Reference Board/Kit
Product(s) embedded on a PCB with a focus on specific applications and defined use cases that may include
software. PCB and auxiliary circuits are optimized for the requirements of the target application.
Note: Boards do not necessarily meet safety, EMI, quality standards (for example UL, CE) requirements

User guide
2
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Important notice
Important notice
“Evaluation Boards and Reference Boards” shall mean products embedded on a printed circuit board
(PCB) for demonstration and/or evaluation purposes, which include, without limitation, demonstration,
reference and evaluation boards, kits and design (collectively referred to as “Reference Board”).
Environmental conditions have been considered in the design of the Evaluation Boards and Reference
Boards provided by Infineon Technologies. The design of the Evaluation Boards and Reference Boards
has been tested by Infineon Technologies only as described in this document. The design is not qualified
in terms of safety requirements, manufacturing and operation over the entire operating temperature
range or lifetime.
The Evaluation Boards and Reference Boards provided by Infineon Technologies are subject to functional
testing only under typical load conditions. Evaluation Boards and Reference Boards are not subject to the
same procedures as regular products regarding returned material analysis (RMA), process change
notification (PCN) and product discontinuation (PD).
Evaluation Boards and Reference Boards are not commercialized products, and are solely intended for
evaluation and testing purposes. In particular, they shall not be used for reliability testing or production.
The Evaluation Boards and Reference Boards may therefore not comply with CE or similar standards
(including but not limited to the EMC Directive 2004/EC/108 and the EMC Act) and may not fulfill other
requirements of the country in which they are operated by the customer. The customer shall ensure that
all Evaluation Boards and Reference Boards will be handled in a way which is compliant with the relevant
requirements and standards of the country in which they are operated.
The Evaluation Boards and Reference Boards as well as the information provided in this document are
addressed only to qualified and skilled technical staff, for laboratory usage, and shall be used and
managed according to the terms and conditions set forth in this document and in other related
documentation supplied with the respective Evaluation Board or Reference Board.
It is the responsibility of the customer’s technical departments to evaluate the suitability of the
Evaluation Boards and Reference Boards for the intended application, and to evaluate the completeness
and correctness of the information provided in this document with respect to such application.
The customer is obliged to ensure that the use of the Evaluation Boards and Reference Boards does not
cause any harm to persons or third party property.
The Evaluation Boards and Reference Boards and any information in this document is provided "as is"
and Infineon Technologies disclaims any warranties, express or implied, including but not limited to
warranties of non-infringement of third party rights and implied warranties of fitness for any purpose, or
for merchantability.
Infineon Technologies shall not be responsible for any damages resulting from the use of the Evaluation
Boards and Reference Boards and/or from any information provided in this document. The customer is
obliged to defend, indemnify and hold Infineon Technologies harmless from and against any claims or
damages arising out of or resulting from any use thereof.
Infineon Technologies reserves the right to modify this document and/or any information provided
herein at any time without further notice.

User guide
3
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Safety precautions
Safety precautions
Note: Please note the following warnings regarding the hazards associated with development systems
Table 1 Safety precautions
Warning: The DC link potential of this board is up to 1000 VDC. When measuring
voltage waveforms by oscilloscope, high voltage differential probes must be used.
Failure to do so may result in personal injury or death.
Warning: The evaluation or reference board contains DC bus capacitors which take
time to discharge after removal of the main supply. Before working on the drive
system, wait five minutes for capacitors to discharge to safe voltage levels. Failure to
do so may result in personal injury or death. Darkened display LEDs are not an
indication that capacitors have discharged to safe voltage levels.
Warning: The evaluation or reference board is connected to the grid input during
testing. Hence, high-voltage differential probes must be used when measuring voltage
waveforms by oscilloscope. Failure to do so may result in personal injury or death.
Darkened display LEDs are not an indication that capacitors have discharged to safe
voltage levels.
Warning: Remove or disconnect power from the drive before you disconnect or
reconnect wires, or perform maintenance work. Wait five minutes after removing
power to discharge the bus capacitors. Do not attempt to service the drive until the bus
capacitors have discharged to zero. Failure to do so may result in personal injury or
death.
Caution: The heat sink and device surfaces of the evaluation or reference board may
become hot during testing. Hence, necessary precautions are required while handling
the board. Failure to comply may cause injury.
Caution: Only personnel familiar with the drive, power electronics and associated
machinery should plan, install, commission and subsequently service the system.
Failure to comply may result in personal injury and/or equipment damage.
Caution: The evaluation or reference board contains parts and assemblies sensitive to
electrostatic discharge (ESD). Electrostatic control precautions are required when
installing, testing, servicing or repairing the assembly. Component damage may result
if ESD control procedures are not followed. If you are not familiar with electrostatic
control procedures, refer to the applicable ESD protection handbooks and guidelines.
Caution: A drive that is incorrectly applied or installed can lead to component damage
or reduction in product lifetime. Wiring or application errors such as undersizing the
motor, supplying an incorrect or inadequate AC supply, or excessive ambient
temperatures may result in system malfunction.
Caution: The evaluation or reference board is shipped with packing materials that
need to be removed prior to installation. Failure to remove all packing materials that
are unnecessary for system installation may result in overheating or abnormal
operating conditions.

User guide
4
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Table of contents
Table of contents
About this document....................................................................................................................... 1
Important notice ............................................................................................................................ 2
Safety precautions.......................................................................................................................... 3
Table of contents............................................................................................................................ 4
1Introduction .......................................................................................................................... 5
1.1 Kit contents .............................................................................................................................................5
1.2 Getting started.........................................................................................................................................6
1.3 Board details ...........................................................................................................................................6
1.4 Additional learning resources.................................................................................................................7
1.5 Technical support....................................................................................................................................7
Document conventions ................................................................................................................... 8
1.6 Abbreviations and definitions.................................................................................................................8
2Kit operation ......................................................................................................................... 9
2.1 Theory of operation.................................................................................................................................9
2.2 Using the machine learning gesture classification code example ......................................................11
2.2.1 Operation .........................................................................................................................................11
3Hardware .............................................................................................................................13
3.1 Schematics ............................................................................................................................................13
3.2 Hardware functional description..........................................................................................................13
3.2.1 Digital MEMS microphone (IM69D130) ............................................................................................13
3.2.2 Digital barometric pressure sensor (DPS310) .................................................................................14
3.2.3 The motion sensor ...........................................................................................................................14
3.2.4 Audio codec (WM8960).....................................................................................................................15
3.2.4.1 Audio jack socket and type selection switch .............................................................................16
3.2.4.2 I2S master clock (MCLK) source .................................................................................................17
3.2.5 Piezoelectric MEMS analog microphone (VM1010) with preamplifier ...........................................18
3.2.6 OLED display module.......................................................................................................................19
3.2.6.1 I2C level translator for OLED display module ............................................................................20
3.2.7 Arduino™-compatible headers (J1, J2, J3, and J4).........................................................................20
3.2.8 I2C device addresses........................................................................................................................23
3.3 IoT sense expansion board rework.......................................................................................................23
3.3.1 Rework on audio codec MCLK source .............................................................................................23
3.3.2 Rework for the baseboard MCU I2S external clock.........................................................................23
3.3.3 Rework for motion sensor to select interface SPI or I2C ................................................................24
3.3.4 Rework for barometric pressure sensor to configure the I2C device address...............................25
3.3.5 Rework for PDM microphone power source selection ...................................................................26
3.3.6 Rework for analog microphone power source selection................................................................27
3.4 Bill of materials......................................................................................................................................28
Revision history.............................................................................................................................29
Disclaimer.....................................................................................................................................30

User guide
5
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Introduction
1Introduction
Thank you for your interest in the IoT sensor expansion kit (CY8CKIT-028-SENSE). This kit is intended as a
companion to add common sensors, audio components, and a user interface to an Arduino™UNO - based
baseboard.
This kit targets two main applications:
•Audio applications: The kit includes two PDM microphones and one analog microphone. It also has an
audio codec with an audio jack socket connector.
•Machine Learning (ML) applications: The kit includes multiple sensors to generate input data to feed ML
algorithms, such as a 6-axis motion sensor, a pressure and temperature sensor, and the microphones.
This kit guide provides details on the kit contents, hardware, schematics, and BOM.
1.1 Kit contents
The kit has the following contents, as shown in Figure 1.
•IoT sense expansion board
•Quick start guide
Figure 1 CY8CKIT-028-SENSE IoT sense expansion kit contents
Inspect the contents of the kit; if you find any part missing, contact your nearest Infineon sales office for help.
Go to Technical Support for more information on Infineon sales offices and support.

User guide
6
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Introduction
1.2 Getting started
The following sections help you get acquainted with the kit:
•The Kit operation chapter describes the theory of operation and major features of the kit.
•The Hardware chapter provides a detailed hardware description, kit schematics, and bill of materials (BOM).
•For programming and debugging details, see the CY8CKIT-062S2-43012 and CY8CKIT-064B0S2-4343W kit
guides.
The board plugs into any Arduino™ UNO - compatible development platforms from Infineon. This guide will
demonstrate using the CY8CKIT-062S2-43012 or CY8CKIT-064B0S2-4343W as the baseboard. The
CY8CKIT-028-SENSE IoT sense expansion kit does not have any programmable device on the board, but it
contains a configurable audio codec that uses I2C as the configuration interface. The PSoC™device present on
the baseboard, such as the CY8CKIT-062S2-43012 or CY8CKIT-064B0S2-4343W, requires firmware, which you
can develop with the ModusToolbox™Software Environment (v2.3.1 or later).
1.3 Board details
The board has the following features:
•High-precision, excellent pressure noise performance and high-stability XENSIV™digital barometric air
pressure sensor with a built-in temperature sensor
−Operation range 300 hPa–1200 hPa
−Sensor precision 0.002 hPa
−Relative accuracy ±0.06 hPa
−Pressure temperature sensitivity of 0.5 Pa/K
−Temperature accuracy ±0.5°C
•Two high-performance XENSIV™MEMS digital microphones making use of Infineon’s dual-backplate MEMS
technology to deliver a 105-dB dynamic range and high-output linearity up to 130 dBSPL
−69 dB(A) signal-to-noise ratio
−Less than 1 percent distortions up to 128 dBSPL (AOP - 130 dBSPL)
−Digital (PDM) interface with 6-μs group delay at 1 kHz
−Tight sensitivity (-36 ±1 dB) and phase (± 2 deg) tolerances
−28-Hz low-frequency roll-off
•A motion sensor with a 3-axis accelerometer and gyroscope (the Rev ** kit has a BMX160 motion sensor,
which supports a 3-axis magnetometer too)
•Wake-on-sound piezoelectric MEMS microphone
•Low-power stereo audio codec featuring Class-D speaker drivers to provide 1 W per channel into 8-Ω loads
and an audio jack socket
•I2C-based 124 x 64 OLED display
•Arduino™UNO compatible headers

User guide
7
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Introduction
The IoT sense expansion shield pinout is shown in Figure 2. For pin assignment details, see section 3.2.7
Arduino™-compatible headers (J1, J2, J3, and J4).
Figure 2 IoT sense expansion shield
1.4 Additional learning resources
An overview of PSoC™devices is available in the PSoC™6 web page. This web page includes a list of PSoC™
device families, integrated design environments (IDEs), and associated development kits. In addition, refer to
the following documents to get started with PSoC™6 devices:
•AN228571 –Getting started with PSoC™ 6 MCU on ModusToolbox™ software
•PSoC™ 6 technical reference manuals
1.5 Technical support
For assistance, visit Technical Support. Visit community.infineon.com to ask your questions in Infineon
developer community.

User guide
8
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Introduction
Document conventions
Conventions
Convention
Explanation
File > Open
Represents menu paths: File > Open > New Project.
Bold
Emphasizes heading levels, column headings, table and figure
captions, screen names, windows, dialog boxes, menus and sub-menus
Displays commands, menu paths, and icon names in procedures:
Click the File icon and then click Open.
Italics
Denotes variable(s) and reference(s)
Displays file names and reference documentation:
Read about the sourcefile.hex file in the PSoC Creator User Guide.
Courier New
Denotes APIs, functions, interrupt handlers, events, data types, error
handlers, command line inputs, code snippets
Times New Roman
Displays an equation:
2 + 2 = 4
>
Indicates that a cascading sub-menu opens when you select a menu
item
1.6 Abbreviations and definitions
Abbreviations
Abbreviation
Definition
ADC
Analog-to-Digital Converter
BOM
Bill of Materials
DAC
Digital-to-Analog Converter
IDE
Integrated Development Environment
I2C
Inter Integrated Circuit interface
I2S
Inter Integrated Circuit Sound Bus
IMU
Inertial Measurement Unit
IoT
Internet of Things
LED
Light Emitting Diode
MEMS
Micro Electro Mechanical System
MIC
Microphone
OLED
Organic Light Emitting Diode
PCM
Pulse Code Modulation
PDM
Pulse Density Modulation
PSoC™
Programmable System-on-Chip
SPI
Serial Peripheral Interface

User guide
9
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Kit operation
2Kit operation
2.1 Theory of operation
The IoT sense expansion kit is an Arduino™-compatible expansion shield to easily interface multiple sensors
with PSoC™6 platform pioneer kits for audio and ML applications. This shield contains PDM microphones and a
barometric pressure sensor from Infineon’s XENSIV™family, I2S-based stereo audio codec from Cirrus Logic,
analog MEMS microphone from Vesper, a motion sensor from Bosch, and an 128x64 OLED display.
This shield is supported by ModusToolbox™ software examples with the CY8CKIT-062S2-43012 and CY8CKIT-
064B0S2-4343W companion kits (referred to as the “baseboard”).
Figure 3 CY8CKIT-028-SENSE IoT sense expansion kit connected to a CY8CKIT-062S2-43012 baseboard
PDM Mic
1
PDM Mic
2
PDM CLK
PDM DATA
I2C
Audio
Jack
HP_R
HP_L
MIC
Pressure
Sensor
OLED
Display
I2S
Motion sensor
(IMU)
PDM1_VDD
PDM2_VDD
VCC_3V3
VCC_3V3
VCC_5V
Functional Block Diagram
SPI
Amplified Mic Signal
Digital INT Signal
PDM1_VDD
PDM2_VDD
VCC_5V
VCC_3V3
VIO_REF
VM_VDD
VIO_REF
MODE select
Vesper
Analog Mic
VM_VDD
Arduino
Headers
VIO_REF
I2C
I2C
I2C
VIO_REF
VIO_REF
VIO_REF
VCC_3V3
VCC_3V3
Infineon Parts
Non Infineon Parts
Power Supply
Optional Power Supply
Audio Codec
MCLK_OSC
PSoC_MCLK
I2S_IF Crystal
Oscillator
VIO_REF
Signal Path
Optional Signal Path
VM_VDD : 1.8V to 3.3V
PDM1_VDD : 1.8V to 3.3V
PDM2_VDD : 1.8V to 3.3V
VIO_REF : 1.8V to 3.3V
VCC_3V3 : 3.3V
VCC_5V : 5V
POWER RAIL VOLTAGES
LEGEND
Level
Translator I2C_3V3
VCC_3V3
Preamp
VREF
VREF
Analog Mic Signal
Figure 4 CY8CKIT-028-SENSE IoT sense expansion kit functional block diagram

User guide
10
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Kit operation
The kit comes with the IoT sense expansion board. Figure 5 shows the components on the IoT sense expansion
board.
Figure 5 IoT sense expansion board details
The board has the following peripherals:
1. XENSIV™digital MEMS microphones (U1, U2): These are two Infineon digital MEMS microphones are used
to capture sound and generate digital audio data, which is transferred through the PDM interface.
2. XENSIV™digital barometric air pressure sensor (U3): This is an Infineon digital MEMS barometric
pressure sensor with built-in temperature sensor. This sensor uses I2C to transfer the sensor data.
3. Arduino™UNO R3 compatible power header (J1): This is an Arduino™-compatible header to interface
with the PSoC™6 baseboard, which has Arduino™-compatible interface female connector to provide power
to this shield.
4. Arduino™UNO R3 compatible I/O headers (J2, J3, J4): These are the Arduino™-compatible headers to
interface the PSoC™6 baseboard, which has an Arduino™-compatible interface female connector to provide
the I/O interface between the baseboard and the shield.
5. OLED module (ACC6): This is a 0.96-inch, 128 x 64 OLED display, which can interface with PSoC™6 MCU via
I2C.
6. Vesper piezoelectric MEMS analog microphone (U5): An analog piezoelectric MEMS microphone with a
wake-on-sound mode that allows the detection of voice activity while consuming only 10 μA of supply
current.
7. Audio codec (U4): A low-power stereo audio codec with built-in Class-D audio amplifier capable of driving
1-W speaker at 8 ohm.
8. 3.5-mm stereo audio jack socket (J5): A 4-pin audio jack socket (TRRS) to connect a stereo headphone
with a microphone.
9. Audio jack socket type selection switch (SW1): This switch is used to change the audio jack socket type
(AHJ or OMPT).
10. Crystal oscillator (Y1): This is a 12.288 MHz crystal oscillator used for generating the I2S MCLK for the audio
codec and I2S peripherals of PSoC™6 MCU.
11. Motion sensor (U6): This kit contains a motion sensor with a 3-axis accelerometer and gyroscope, which
can be interfaced with a PSoC™ 6 MCU via SPI (default interface) or I2C.
Note: The Rev *B version of this kit has BMI160, which does not support the magnetometer feature.
12. I2C level translator (U7): This level shifter is used to generate a constant 3.3-V level I2C signal from various
I2C target-level voltages.

User guide
11
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Kit operation
13. Preamplifier (U8): This is an opamp-based non-inverting amplifier used to preamplify the analog MIC audio
output.
See 3.2 Hardware functional description for details on various hardware blocks.
2.2 Using the machine learning gesture classification code example
CY8CKIT-028-SENSE can be used with the CY8CKIT-062S2-43012 and CY8CKIT-064B0S2-4343W baseboards. The
following sections describe on how to create a project to run on the baseboard that uses the CY8CKIT-028-
SENSE shield. For a detailed description of the project, see the example’s readme file in the GitHub repository.
2.2.1 Operation
If using CY8CKIT-064B0S2-4343W, the PSoC™64 device must be provisioned with keys and policies before being
programmed. Follow the instructions in the "Secure Boot" SDK user guide to provision the device. If kit is
already provisioned, copy-paste the keys and policy folders to the application folder.
1. Connect the CY8CKIT-028-SENSE shield to the baseboard kit.
2. Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
3. Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and
115200 baud.
4. In the ModusToolbox™ software (either Eclipse IDE for ModusToolbox™ or command-line interface), build
and program the “Machine Learning Gesture Classification” code example on to the kit. See the example’s
readme for programming details.
5. After programming, the application starts automatically. Confirm that “Gesture Classification Example” and
some log data are printed on the UART terminal, the gesture classifications and confidence are updated
continuously.
6. Hold the board with the following orientation while moving your arm to complete a gesture.
Figure 6 Holding posture of CY8CKIT-028-SENSE with baseboard for gesture classification
application

User guide
12
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Kit operation
7. Perform a counter-clockwise circle movement continuously. Confirm that the UART terminal prints the
gesture as Circle, and the confidence of the circle increases past 70%. For best results, repeatedly perform a
circle movement that has a diameter of one foot, and complete one circle per second.
8. Perform a counter-clockwise square movement continuously. Confirm that the UART terminal prints the
gesture as Square, and the confidence of the square increases past 70%. For best results, repeatedly
perform a square movement that has a side length of one foot, and complete one square in two seconds.
9. Perform a side-to-side movement (left <-> right) continuously, confirm that the UART terminal prints the
gesture as Side-to-side, and the confidence increases past 70%. For best results, repeatedly perform a one-
foot-wide left-to-right movement in half-a-second.
10. When not performing any of the gestures above, confirm that the UART terminal prints the gesture as None.
Note: See the example’s readme file for up to date instructions.

User guide
13
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
3Hardware
3.1 Schematics
See the schematic files available on the kit webpage.
3.2 Hardware functional description
3.2.1 Digital MEMS microphone (IM69D130)
The CY8CKIT-028-SENSE kit contains two digital PDM MEMS microphones from Infineon Technologies sharing
the same PDM bus. Each PDM microphone has a SELECT pin; if this pin is connected to GND, the PDM data is
available on the falling edge of the PDM clock. If this pin is connected to VDD, the PDM data is available on the
rising edge of the PDM clock.
By default, these PDM microphones are powered by VIO_REF to match the I/O logic level, but for low-power
operation, an optional resistor is provided to power the microphones from a GPIO of the PSoC™6 device.
Figure 7 Schematic of digital MEMS microphones

User guide
14
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
3.2.2 Digital barometric pressure sensor (DPS310)
The kit contains Infineon’s digital MEMS barometric pressure sensor with a built-in temperature sensor
interfaced with PSoC™6 MCU via I2C. This pressure sensor supports the SPI interface also, but this shield is
designed to use it with I2C only.
The SDO pin of the pressure sensor is pulled down with a 100-K resistor, which determines the I2C device
address of the sensor. If the pull-down resistor is loaded, the 7-bit I2C device address will be 0x76; if not, the
address will be 0x77. This pressure sensor has a separate I/O power supply pin (VDDIO), which is connected to
VIO_REF to match the logic levels of both I/O lines of PSoC™6 MCU and sensors.
Figure 8 Schematic of the digital barometric pressure sensor
3.2.3 The motion sensor
This kit contains a motion sensor, also known as the Inertial Measurement Unit (IMU), that provides precise
acceleration and gyroscopic angular rate in each spatial direction.
Note: The Rev *B version of this kit has BMI160, which does not support the magnetometer feature.
The interface can be configured for both I2C and SPI. See section 3.3.3 Rework for motion sensor to select
interface SPI or I2C for more details.

User guide
15
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 9 Schematic of the 6-axis motion sensor
3.2.4 Audio codec (WM8960)
This kit contains Cirrus Logic’s audio codec, which is a low-power, high-quality stereo codec. It contains Class-D
stereo speaker drivers, which provide 1 W per channel into 8-Ω speaker loads with a 5 V supply. It is interfaced
with PSoC™6 MCU on the baseboard via I2S.
This codec has an internal PLL, which generates various system clock frequencies. This kit has a crystal
oscillator to feed the external clock to the audio codec; it also has a provision for resistor bypass to provide
external clock from the PSoC™6 MCU on the baseboard. See sections 3.3.1 Rework on audio codec MCLK
source and 3.3.2 Rework for the baseboard MCU I2S external clock for details.
To configure the registers of the audio codec, an I2C interface is provided to the PSoC™6 MCU on the
baseboard. This I2C bus is shared between all components using the I2C interface and PSoC™6 MCU on the
baseboard. The default 7-bit I2C device address is 0x34.
Note: The KitProg3 UART’s RTS and CTS pins of the baseboard are multiplexed with the I2S interface on
the shield. This would cause the noise in the output of the audio codec. Remove the resistors R18
and R19 on the baseboard to disconnect the UART RTS and CTS signals. See the Board details
section of the CY8CKIT-062S2-43012 and CY8CKIT-064B0S2-4343W kit guides for details.
Note: When using the audio codec in this shield, do not configure the I2S peripheral in full-duplex mode
(RX and TX enabled). Only enable one direction per time. This avoids noise on the I2S lines when
running the RX and TX at the same time.

User guide
16
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 10 Schematic of the audio codec
3.2.4.1 Audio jack socket and type selection switch
An audio jack socket is provided to connect headphones to the audio codec. A switch and resistor are provided
to select the microphone for different headphones with OMTP and AHJ connector interface types.

User guide
17
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 11 Schematic of the audio jack socket and type selection switch
3.2.4.2 I2S master clock (MCLK) source
The audio codec I2S MCLK can be sourced by either by the MCU_MCLK signal from the baseboard connected
through the J3 Header (J3.1), or the OSC_MCLK signal from the crystal oscillator (Y1). By default, the crystal
oscillator is used.
Figure 12 Schematic of I2S MCLK sourcing with resistor provision
3.2.4.2.1 Crystal oscillator
The kit contains a 12.288 MHz crystal oscillator to provide an external MCLK for the audio codec. The same
clock can source the I2S_IF (external CLK for the I2S block of PSoC™6 MCU) with a resistor provision. See
section 3.3.1 Rework on audio codec MCLK source for details.

User guide
18
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 13 Schematic of the crystal oscillator
3.2.5 Piezoelectric MEMS analog microphone (VM1010) with preamplifier
The kit contains Vesper’s analog piezoelectric MEMS microphone. This is a low-noise, single-ended analog
MEMS microphone with a wake-on-sound mode that allows the detection of voice activity while consuming
only 10 μA of supply current (or 18 μW of power).
In the wake-on-sound mode, the microphone detects sounds in the voice band above a configurable acoustic
threshold level. When the microphone detects sound above the threshold, it instantly alerts the system of the
acoustic event. The system can then switch the VM1010 to normal mode with full audio output within 200 μs.
This is fast enough for VM1010 to capture the sound that exceeds the threshold and send it to the system for
processing.
The analog microphone signal is preamplified using a non-inverting amplifier whose output is given to the SAR
ADC of the PSoC™6 MCU on the baseboard.
The acoustic threshold level can be adjusted by varying the resistor value between GA1 and GA2 as specified:
•Open –Max acoustic threshold
•90.9K –Mid acoustic threshold
•18K –Min acoustic threshold (default setting)

User guide
19
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 14 Analog microphone with its preamplifier
3.2.6 OLED display module
The kit contains a monochrome 0.96” 128 x 64 OLED display module. This display module has high contrast and
works without backlight. This display is interfaced to the PSoC™6 device via I2C. The interface circuitry is
provided on this kit as shown in Figure 15. The 7-bit I2C device address of OLED display module is 0x3C.

User guide
20
002-32652 Rev. *C
2023-05-31
CY8CKIT-028-SENSE IoT Sense Expansion Kit User Guide
Hardware
Figure 15 Schematic of the OLED display module interface
3.2.6.1 I2C level translator for OLED display module
The kit contains OLED display that operates at a voltage range of 2.5 VDC to 5.5 VDC, but the baseboard MCU
can run at a voltage level of 1.8 VDC to 3.3 VDC. To make sure that the display works at 1.8 VDC, a level
translator is used to generate I2C signals at a voltage level that display works with.
Figure 16 Schematic of the I2C level translator
3.2.7 Arduino™-compatible headers (J1, J2, J3, and J4)
The kit has four Arduino™-compatible headers: J1, J2, J3, and J4 to provide power supply, I2C interface, SPI
interface, I2S interface, PDM interface, and control I/O for sensors to the CY8CKIT-028-SENSE kit from the
baseboard, and provide I2S MCLK to the baseboard.