Microchip Technology WFI32-IoT User manual

EV36W50A
WFI32-IoT Board User's Guide
Introduction
The WFI32-IoT board is a compact, stand-alone and easy-to-use board that helps the user to develop the Internet-
of-Things (IoT) applications with the WFI32E01PC module, a highly integrated Wi-Fi® MCU module that supports
smart Wi-Fi functionalities and premium MCU features. The WFI32E01PC module has a PCB antenna and Trust&GO
hardware secure element, which is pre-provisioned to popular cloud platforms.
The WFI32-IoT board:
• Provides an easy way to connect the embedded application to cloud IoT platforms, such as AWS and Azure
• Includes a PICkit On-board 4 (PKOB4) debugger interface, and requires no external hardware to program and
debug the WFI32E01PC module
• Includes a mikroBUS™ Click™ header, which helps the users to expand the functionalities by connecting to
various MikroElectronika mikroBUS™ Click™ adapter boards
• Requires only a Micro USB cable to power up and program the board
Features
• Certified WFI32E01PC Module
• Four User LEDs
• Two User Configurable Switch
• One Reset Switch
• On-board Temperature Sensor
• On-board Light Sensor
• 32-Mbit External SPI Flash Memory
• mikroBUS™ Socket to Expand Functionality using MikroElectronika Click Boards
• Li-Ion/LiPo Battery Charger with Power Path Management
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 1

Table of Contents
Introduction.....................................................................................................................................................1
Features......................................................................................................................................................... 1
1. Quick References....................................................................................................................................4
1.1. Reference Documentation............................................................................................................4
1.2. Hardware Prerequisites................................................................................................................4
1.3. Software Prerequisites................................................................................................................. 4
1.4. Acronyms and Abbreviations........................................................................................................4
2. Kit Overview............................................................................................................................................ 6
2.1. Kit Contents..................................................................................................................................7
3. Hardware.................................................................................................................................................8
3.1. Power Supply............................................................................................................................... 8
3.2. MPLAB PICKit On-Board 4 (PKOB4)......................................................................................... 10
3.3. USB Connectivity........................................................................................................................11
3.4. mikroBUS Socket....................................................................................................................... 12
3.5. Switches..................................................................................................................................... 13
3.6. LEDs...........................................................................................................................................13
3.7. Temperature Sensor...................................................................................................................13
3.8. Ambient Light Sensor................................................................................................................. 14
3.9. Serial Flash................................................................................................................................ 14
3.10. Secondary Oscillator.................................................................................................................. 15
3.11. WFI32E01PC Module.................................................................................................................15
4. WFI32-IoT Board Out of Box Demo...................................................................................................... 16
5. Appendix A: Reference Circuit.............................................................................................................. 17
5.1. WFI32-IoT Board Schematics.................................................................................................... 17
5.2. WFI32-IoT Board Bill of Materials.............................................................................................. 26
6. Appendix: B Regulatory Approval......................................................................................................... 31
6.1. United States..............................................................................................................................31
6.2. Canada.......................................................................................................................................31
6.3. Europe........................................................................................................................................32
7. Document Revision History...................................................................................................................33
The Microchip Website.................................................................................................................................34
Product Change Notification Service............................................................................................................34
Customer Support........................................................................................................................................ 34
Microchip Devices Code Protection Feature................................................................................................ 34
Legal Notice................................................................................................................................................. 34
Trademarks.................................................................................................................................................. 35
EV36W50A
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 2

Quality Management System....................................................................................................................... 36
Worldwide Sales and Service.......................................................................................................................37
EV36W50A
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 3

1. Quick References
1.1 Reference Documentation
For further details, refer to the following:
•PIC32MZ1025W104 MCU and WFI32E01 Module with Wi-Fi® and Hardware-based Security Accelerator Data
Sheet (DS70005425)
•PIC32MZ W1 Software User’s Guide (DS50003034)
•PIC32MZ1025W104 MCU and WFI32E01 Module with Wi-Fi® and Hardware-based Security Accelerator Errata
(DS80000912)
•MCP1727 1.5A, Low Voltage, Low Quiescent Current LDO Regulator Data Sheet (DS21999)
•MCP9808 ±0.5°C Maximum Accuracy Digital Temperature Sensor (DS20005095)
•MPLAB® XC32 C/C++ Compiler User’s Guide (DS50001686)
•MPLAB® X IDE User’s Guide (DS50002027)
•MPLAB® Snap In-Circuit Debugger User's Guide (DS50002787)
•MPLAB® PICkit™ 4 In-Circuit Debugger User's Guide User Guide (DS50002751)
•SST26VF032B/SST26VF032BA 2.5V/3.0V 32-Mbit Serial Quad I/O™ (SQI™) Flash Memory Data Sheet
(DS20005218).
•Stand-Alone System Load Sharing and Li-Ion/Li-Polymer Battery Charge Management Controller Data Sheet
(DS20002090)
•Universal Serial Bus Specification and Associated Documents (www.usb.org)
•mikroBUS™ Specification (www.mikroe.com/mikrobus)
1.2 Hardware Prerequisites
• EV36W50A (WFI32-IoT board) kit
1.3 Software Prerequisites
• MPLAB® Integrated Development Environment (MPLAB X IDE) tool (version 5.50 or later)
•MPLAB XC32 Compiler (version 2.40 or later)
• MPLAB Snap – www.microchip.com/PG164100
• Released Out of Box (OOB) demo – www.github.com/MicrochipTech/WFI32-IoT
1.4 Acronyms and Abbreviations
Acronyms and Abbreviations Description
ADC Analog-to-Digital Converter
BOM Bill of Material
CVD Capacitive Voltage Divider
GPIO General Purpose Input Output
I2C Inter-Integrated Circuit
ICD In-Circuit Debugger
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Quick References
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User Guide DS50003262A-page 4

...........continued
Acronyms and Abbreviations Description
ICSP In-Circuit Serial Programming
IoT Internet of Things
JTAG Joint Test Action Group
LDO Low-Dropout
LED Light Emitting Diode
MCU Microcontroller
NC Not Connected
OOB Out of Box
OTG On-The-Go
PCB Printed Circuit Board
PKOB PICKit On-Board
PPS Peripheral Pin Select
PWM Pulse Width Modulation
RMII Reduced Media Independent Interface
RTCC Real Time Clock and Calendar
RTOS Real-Time Operating System
RX Receiver
SCL Serial Clock
SDA Serial Data
SMD Surface Mount
SoC System-on-Chip
SPI Serial Peripheral Interface
TX Transmitter
UART Universal Asynchronous Receiver-Transmitter
USB Universal Serial Bus
EV36W50A
Quick References
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User Guide DS50003262A-page 5

2. Kit Overview
The WFI32-IoT board has a single-chip Wi-Fi module that supports rapid prototyping of IoT devices and
demonstrates cloud connectivity.
The WFI32-IoT board:
• Offers various types of on-board sensors, such as a temperature sensor and ambient light sensor to build their
own applications
• Provides on-board sensors that help the user to collect the sensor data and transmit to the cloud
• Provides the WFI32E01PC module, which has a built-in crypto device that helps to make a secure and
authenticated cloud connection
Figure 2-1. WFI32-IoT Board (EV36W50A) – Top View
Status LED (D301)
User Configurable LEDs
(D400, D401, D402 and D403)
Battery Header (J101)
Erase Header (J301)
mikroBUS™ Socket (J402)
Ambient Light
Sensor (U401)
Active LED (D300)
USB Hub IC (U201)
Reset Switch (SW402)
SPI Flash (U403)
WFI32E01PC Module
Power Measurement
Header (J400)
User Configurable
Switch1 (SW401)
User Configurable
Switch2 (SW400)
PKOB4 Micro-B USB (J200)
(Debug USB)
Red LED (D100)
Green LED (D101)
Blue LED (D102)
Voltage Regulator (U102)
EV36W50A
Kit Overview
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Figure 2-2. WFI32-IoT Board (EV36W50A) – Bottom View
Li-Ion/LiPo
Charger (U101)
Voltage Regulator (U104)
PKOB4 Main
Controller (U300)
USB-to-UART Serial
Converter (U202)
Secondary
Oscillator (Y400)
Power Distribution
Switch (U100)
Temperature
Sensor (U402)
2.1 Kit Contents
The EV36W50A (WFI32-IoT board) kit contains the following:
• A WFI32E01PC module mounted on the WFI32-IoT board
• A Type-A male to Micro-B USB cable
Note: If any of the above items are missing in the kit, go to support.microchip.com or contact your local Microchip
Sales office. In this user guide, there is a list of Microchip offices for sales and services provided on the last page.
EV36W50A
Kit Overview
© 2022 Microchip Technology Inc.
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User Guide DS50003262A-page 7

3. Hardware
This chapter describes the hardware features of the WFI32-IoT board.
Figure 3-1. WFI32-IoT Board Block Diagram
Power Switch
(MIC2042)(1)
32.768 kHz
Crystal
Digital Temperature
Sensor
(MCP9808)(1)
Reset Button
Two User Buttons
mikroBUSTM Socket
Wi-Fi Module
(WFI32E01PCI)(1)
GPIO/I2C/UART/SPI
External SPI Flash
(SST26VF032B)(1)
SPI1
Four User
Configurable LEDs
GPIO
MCLR
SOSC
I2C
GPIO
Ambient Light
Sensor
I2C
ICSP PGEC/PGED
PKOB4 Controller
(ATSAME70N21B-CNT)(1)
USB-UART Converter
(MCP2200)(1)
USB D+, D-
UART
USB
UART1
UART3 UART
UART2/
SPI2
SPI
Battery
Management
(MCP73871)(1)
Li-PO Battery
Connector
5V
4.2V
Micro
USB
Type B
USB Hub
(USB2514B-IM2)(1)
LDO
(MCP1727)(1)
LDO
(MCP1727)(1)
3.3V
MEMS Oscillator
(DSC6011HI1B-024)(1)
MEMS Oscillator
(DSC6011JI1B-012)(1)
Microchip Devices
WFI32-IoT Board
Note:
1. Using Microchip’s total system solution, which includes complementary devices, software drivers and
reference designs, is highly recommended to ensure the proven performance of the WFI32-IoT boards. For
more details, go to support.microchip.com or contact your local Microchip Sales office.
3.1 Power Supply
The following are the power supply sources to power the WFI32-IoT board; see the following figure:
• PKOB4 Micro-B USB (Debug USB) (J200)
• Battery Header (J101)
EV36W50A
Hardware
© 2022 Microchip Technology Inc.
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User Guide DS50003262A-page 8

Figure 3-2. WFI32-IoT Board Power Supply Block Diagram
Battery Charger
MCP73871
Li-Ion/Li-Po
LDO
MCP1727
LDO
MCP1727
3V3_PKoB
3V3_Mod
USB
WFI32E01PC
Module
USB HUB
USB2514B
PKoB4
ATSAME70N
Peripherals
5V0
VBAT_OUT
Battery
Connector
VBAT
VBUS
PKOB4 Micro-B USB (Debug USB) (J200)
The Debug USB (J200) supplies power to the WFI32-IoT board from the host PC using Type-A male to Micro-B USB
cable.
Note: The maximum available current from the Debug USB (J200) is limited to 500 mA. The current is shared
between charging the external battery (if connected) and the target application section.
Battery Header (J101)
Connect a 4.2V Li-ion/Li-Po battery to the battery header (J101).
Notes:
1. The 4.2V Li-ion/Li-Po battery is not a part of the EV36W50A kit.
2. The minimum recommended battery capacity is 400 mAh with a battery charge voltage of 4.2V.
3. Uses a standard battery connector, which is a 2 pin, 2 mm pitch and right angle male battery header.
3.1.1 Li-ion/Li-Po Battery Charger (U101)
The WFI32-IoT board features an on-board MCP73871 Li-ion/Li-Po battery charger. The battery management circuit
automatically handles the selection between the USB power supply and battery supply. The current is shared
between charging the battery (if connected) and the target application section. For more details on the MCP73871
Li-ion/Li-Po battery charger, refer to the Stand-Alone System Load Sharing and Li-Ion/Li-Polymer Battery Charge
Management Controller Data Sheet (DS20002090).
Note: The charger is configured to limit the charge current to 100 mA to prevent the overcharging of small capacity
batteries.
WARNING
The MCP73871 has a battery charge voltage of 4.2V and ensures that the battery has the same charge
voltage.
3.1.2 Voltage Regulators (U102 and U104)
The following are the two on-board MCP1727 voltage regulators on the WFI32-IoT board that generate +3.3V power
supply:
•U102 – Generates +3.3V that powers the WFI32E01PC module along with the associated circuits
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User Guide DS50003262A-page 9

•U104 – Generates +3.3V that powers the USB hub IC (U201), PKOB4 micro controller (U300), along with the
associated circuits that connect the PKOB4 debugger to a host PC
For more details on the U102 and U104 voltage regulators, refer to the MCP1727 1.5A, Low Voltage, Low Quiescent
Current LDO Regulator Data Sheet (DS21999).
3.1.3 Power Measurement Header (J400)
The current measurement header (J400) measures the total current consumed by the WFI32E01PC module using a
multimeter. To measure the total current consumption of the WFI32E01PC module, remove the jumper (JP401) from
the J400 header and connect a voltmeter across its pins. A 1Ω resistor option available on-board across the jumper
gives a 1:1 relationship between the voltage drop and current consumption.
For the direct current measurement, use a jumper wire to short the J400 pin 1-2 and connect a current clamp probe,
for example, the TEKTRONIX TCP0030A current probe. The normal probes with long wires may add a load to the
current path and introduce a voltage drop, which leads to incorrect readings.
For the current measurement in terms of voltage, mount the R400 with 0.1Ω resistor for Active mode and 1Ω resistor
for Sleep mode current consumption using a voltage probe or multimeter.
3.2 MPLAB PICKit On-Board 4 (PKOB4)
The MPLAB PICKit On-Board 4 (PKOB4) is a new generation of in-circuit debugger. The MPLAB PKOB4 programs
faster than its predecessor and is designed to use a high-speed USB 2.0 interface, providing a feature-rich
debugging experience via one USB cable. The MPLAB PKOB4 is intended to support the programming and
debugging interface. For more details on the MPLAB PKOB4, refer to the MPLAB Snap In-Circuit Debugger User's
Guide (DS50002787).
Features
• Connects to a computer through a Micro-B USB cable
• Programs devices using MPLAB X IDE or MPLAB X IPE
• Supports multiple hardware and software breakpoints, stopwatch and source code file debugging
• Debugs the application in real time
• Sets breakpoints based on internal events
• Monitors internal file registers
• Debugs at full speed
• Configures pin drivers
• Field-upgradeable through an MPLAB X IDE firmware download
• Adds new device support and features by installing the latest version of MPLAB X IDE
Note: The MPLAB X IDE is available for free at www.microchip.com/mplab-x-ide.
• Indicates debugger status using on-board LEDs
3.2.1 Recovery Method
When the MPLAB PKOB4 is unresponsive, use the MPLAB X IDE tool to recover the WFI32-IoT board through the
following recovery method:
1. Short the pin1 and pin2 of the connector (J301) to the ground for approximately 15 seconds; see the following
figure.
Note: Ensure that the WFI32-IoT board is turned ON to perform the recovery method.
EV36W50A
Hardware
© 2022 Microchip Technology Inc.
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User Guide DS50003262A-page 10

Figure 3-3. WFI32-IoT Board (EV36W50A) – Recovery Method
Connector (J301)
2. Open the latest version of MPLAB X IDE.
3. The following figure illustrates the opening window of the MPLAB X IDE. From the “Debug” drop-down list,
select Hardware Tool Emergency Boot Firmware Recovery.
Figure 3-4. MPLAB® X IDE Opening Window
4. Follow the instructions shown in the preceding figure to bring the tool back to factory condition. For additional
information on the MPLAB PKOB4, refer to the MPLAB® PICkit™ 4 In-Circuit Debugger User's Guide
(DS50002751) and MPLAB Snap In-Circuit Debugger User's Guide (DS50002787).
3.3 USB Connectivity
The WFI32E01PC module has an integrated full-speed USB peripheral. This feature enables the user to implement
USB functionality through the Micro-AB USB connector (J200) on the WFI32-IoT board.
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User Guide DS50003262A-page 11

3.4 mikroBUS Socket
A mikroBUS socket (J402) expands the functionality of the WFI32-IoT board using the MikroElectronika mikroBUS™
Click™ adapter boards. The mikroBUS connector consists of the following:
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C)
• Universal Asynchronous Receiver-Transmitter (UART)
• Reset (GPIO)
• Pulse Width Modulation (PWM)
• Analog and interrupt lines
• 3.3V and 5V power lines
Table 3-1. mikroBUS Socket Pinout Details
Pin Number Pin on mikroBUS
Socket
Pin Description of mikroBUS
Socket
Pin on WFI32E01PC Module(1)
1 AN Analog input AN14/ANN0/CVD14/CVDR14/RPA14/RA14
2 RST Reset ETH_CLK_OUT/CVDT10/RPC12/RC12
3 CS SPI Chip Select CVDT13/ETXD0/RPC15/RC15
4 SCK SPI Clock SCK2/RPA11/RA11
5 MISO SPI Host Input Client Output PTA_WLAN_ACTIVE/RPK5/RK5
6 MOSI SPI Host Input Client Input BT_CLK_OUT/RPK4/RK4
7 +3.3V 3.3V power +3.3V
8 GND Ground GND
9 GND Ground GND
10 +5V 5V power +5V
11 SDA I2C Data SDA1/RPA5/RA5
12 SCL I2C Clock SCL1/RPA4/RA4
13 TX UART transmit PTA_BT_ACTIVE/RPK7/RK7
14 RX UART receive TDI/PGD4/AN9/CVD9/CVDR9/RPB9/RB9
15 INT Hardware interrupt ANN1/CVD15/CVDR15/RPA13
16 PWM PWM output ANA0/RPB12/RB12
Notes:
1. For more details on the WFI32E01PC module pins, refer to the PIC32MZ1025W104 MCU and WFI32E01
module with Wi-Fi® and Hardware-based Security Accelerator Data Sheet (DS70005425).
2. The SPI interface on the click board can operate up to 12.5 MHz, and the WFI32E01PC module supports up to
20 MHz.
3. To have a fully functional UART click board, the R432 and R435 (default) resistors are populated on the
WFI32-IoT board.
4. To have a fully functional CAN click board, populate the R433 and R434 resistors on the WFI32-IoT board.
5. To have a fully functional OLED click board, depopulate the R436 resistor on the WFI32-IoT board.
EV36W50A
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User Guide DS50003262A-page 12

3.5 Switches
The following are the available switches on the WFI32-IoT board:
• User-configurable switches – (SW400) and (SW401)
• Reset switch (SW402) – Connected with the MCLR signal of the WFI32E01PC module
In the Idle state, the level of the user-configurable switch is pulled high (+3.3V) and, when the switch is pressed, it
drives the I/O line to low (GND).
Table 3-2. Switches Description
Switch Name Description Pin on WFI32E01PC Module
SW400 User configurable switch2 PGC4/TCK/AN8/CVD8/CVDR8/RPB8
SW401 User configurable switch1 INT0/AN17/CVD17/CVDR17/RPA10
SW402 Reset switch MCLR
3.6 LEDs
The WFI32-IoT on-board LEDs are categorized into three types:
• Power LEDs
– Green (D101) – Charge indicator
– Red (D100) – Low battery indicator
– Blue (D102) – Power indicator
• PKOB4 LEDs
– Green (D300) – ACTIVE indicator
– Yellow (D301) – STATUS indicator
• LEDs related to the WFI32E01PC module:
– Red LED (D400)
– Yellow LED (D401)
– Green LED (D402)
– Blue LED (D403)
The following table lists the LEDs that can be turned ON or OFF using the connected GPIO pins.
Table 3-3. LEDs Description
LED Name Description Pin on WFI32E01PC Module
Red LED (D400) User configurable LED1 ERXDV/CVDT14/RPK12
Yellow LED (D401) User configurable LED2 EMDIO/CVDT15/RPK13
Green LED (D402) User configurable LED3 EMDC/CVDT16/RPK14
Blue LED (D403) User configurable LED4 ERXERR/CVDT7/RPC9
3.7 Temperature Sensor
The MCP9808 digital temperature sensor converts temperatures between -20°C and +100°C to a digital word with
±0.25°C/±0.5°C (typical/maximum) accuracy. For more details, refer to the MCP9808 ±0.5°C Maximum Accuracy
Digital Temperature Sensor (DS20005095).
The following are the additional features of the MCP9808 digital temperature sensor:
• Accuracy
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– ±0.25°C (typical) from -40°C to +125°C
– ±0.5°C (maximum) from -20°C to +100°C
• User-Selectable Measurement Resolution
– 0.5°C
– 0.25°C
– 0.125°C
– 0.0625°C
• User-Programmable Temperature Limits
– Temperature Window Limit
– Critical Temperature Limit
• User-Programmable Temperature Alert Output
• Operating Voltage Range – 2.7-5.5V
• Operating Current – 200 μA (typical)
• Shutdown Current – 0.1 μA (typical)
The MCP9808 temperature sensor is connected to the WFI32E01PC module through I2C and a GPIO for the
user-configurable alert output.
Note: 7-bit I2C address – 0x18
Table 3-4. MCP9808
Pin Name Description Pin on WFI32E01PC Module
SDA I2C Data SDA1/RPA5
SCL I2C Clock SCL1/RPA4
Alert ASYNC external interrupt TDO/AN7/CVD7/CVDR7/CVDT0/RPB7
3.8 Ambient Light Sensor
A OPT3001 is a sensor that measures the intensity of visible light. The light sensor is mounted on the WFI32-IoT
board for measuring the light intensity.
Table 3-5. Light Sensor
Pin Name Description Pin on WFI32E01PC Module
SDA I2C Data SDA1/RPA5
SCL I2C Clock SCL1/RPA4
INT Interrupt output open-drain TMS/AN6/CVD6/CVDR6/CVDT1/RPB6
3.9 Serial Flash
The WFI32-IoT board has an on-board 32-Mbit external SPI Flash (SST26VF032B) memory for the storage of data.
For more details on the serial Flash, refer to the SST26VF032B/SST26VF032BA 2.5V/3.0V 32-Mbit Serial Quad I/O™
(SQI™) Flash Memory Data Sheet (DS20005218). The following table describes the details of the serial Flash pin
connection.
Table 3-6. Serial Flash Pin Description
Pin Number Pin on Serial Flash
(SST26VF032B)
Pin Description of Serial Flash Pin on WFI32E01PC Module(1)
1 CE Chip Enable SPI1CS/RPA1/RA1
2 SO Serial Data Output for SPI mode SDI1/RPC7/RC7
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...........continued
Pin Number Pin on Serial Flash
(SST26VF032B)
Pin Description of Serial Flash Pin on WFI32E01PC Module(1)
3 WP Write-Protect Not connected
4 VSS Ground GND
5 SI Serial Data Input for SPI mode SDO1/RPC8/RC8
6 SCK Serial Clock SCK1/RPC6/RC6
7 HOLD Hold Not connected
8 VDD Input power supply VDD
Note:
1. For more details on the WFI32E01PC module pins, refer to the PIC32MZ1025W104 MCU and WFI32E01
Module with Wi-Fi® and Hardware-based Security Accelerator Data Sheet (DS70005425).
3.10 Secondary Oscillator
The secondary oscillator (Y400) pin has an on-board 32.768-kHz crystal connected to the SOSCO/PK15 and SOSCI/
PB15 pins of the WFI32E01PC module for the RTCC application.
3.11 WFI32E01PC Module
For more details on the WFI32E01PC module pinout details, refer to the PIC32MZ1025W104 MCU and WFI32E01
Module with Wi-Fi® and Hardware-based Security Accelerator Data Sheet (DS70005425).
Note: The user can configure the Peripheral Pin Select (PPS) pins for any of the supported peripheral functions
based on the end user application.
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User Guide DS50003262A-page 15

4. WFI32-IoT Board Out of Box Demo
The WFI32-IoT board’s Out of the Box (OOB) demo is preloaded with a firmware image that enables the user to
quickly connect and send data to the AWS cloud using the on-board temperature and light sensors. The users can
easily build their own custom projects with software libraries and example codes provided in Harmony v3 framework.
The OOB demo connects to the cloud and allows the user to control the WFI32-IoT board via a web-based interface.
For more details about the code and documentation related to the OOB demo, go to www.github.com/MicrochipTech/
WFI32-IoT.
EV36W50A
WFI32-IoT Board Out of Box Demo
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 16

5. Appendix A: Reference Circuit
5.1 WFI32-IoT Board Schematics
Figure 5-1. Power Distribution Switch for PKOB4
GND
10uF
25V
0603
C102
GND
GND GNDGNDGND
GND
MIC2042
VBIAS
7
VIN
8
VIN
12
EN
2
/FAULT
3
SLEW
9
ILIM
6
VOUT 10
VOUT 11
VOUT 14
PGREF 13
PWRGD 1 UVLOIN
4
GND
5
U100
24.3k
0402
1%
R106
GND
3V3_PKOB
3V3_PKOB 0.1uF
10V
0402
C101
0.1uF
10V
0402
C104
10k
0402
5%
R101
10k
0402
5%
R107
10k
0402
5%
R102
442k
0402
1%
R104
GND
95.3k
0402
1%
R105
5.62k
0402
1%
R109
5V0
i
Power Class
270R
0402
1%
R110
5V0_USBGOOD
5V0_nUSBFLT
0.1uF
10V
0402
C100
22uF
16V
0805
C103
VBUS
10000pF
50V
0402
C105
1
TP103
3ms slew rate
1.5A output current, R83=CLF/ILIM=395/1.5=263.3ohms (22%
tolerance)
4.4V power good threshold,
VOUT(GOOD)=0.23*(1+R104/R110)=0.23*(1+442k/24.3k)=4.41
V
4.1V undervoltage in shutdown threshold,
VUVTH=0.23*(1+95.3k/5.62k)=4.13V
Figure 5-2. Li-Po Battery Connector/Charger
10uF
25V
0603
C106
GND
4.7uF
16V
0603
C108
RED
D100
GND
5V0
GND
5V0
GND
GND
4.7uF
16V
0603
C107
GND
VBAT_OUT
0R
0402
R111
0R
0402
DNP
R117 10k
0402
5%
R118
100k
0402
5%
R119
10k
0402
5%
R115
1k
0402
5%
R112
GREEN
D101
1k
0402
5%
R113
12
HDR-2 Male 1x2
J101
0R
0402
R120
0R
0402
R127
5V0
VBAT_OUT
VBAT
BLUE
D102
4.99k
0402
1%
R114
1
2
4
5
10
11
12
13
14
15
16
17
18
19 20
21
1
TP102
1
TP104
SEL Pin Low: From USB Port, input
current limit governed by USB specs,
PROG2= High,ILIMITUSB=500mA
SEL Pin High: ILIMITAC = 1.65A
PROG1 = 1000V/IREG=
1000/100m=10k, IREG = 100mA
PROG3=1000V/ITERMINATION=1000
V/10mA= 100k
By default, SEL Pin = Low
MCP73871
OUT
VPCC
SEL
3
PROG2
THERM
PG
6
STAT2
7
STAT1/LBO
8
TE
9
VSS
VSS
PROG3
PROG1
VBAT
VBAT
VBAT_SENSE
CE
IN
IN OUT
EP
U101
EV36W50A
Appendix A: Reference Circuit
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 17

Figure 5-3. 3.3V Regulator for WFI32 Module
3V3_REG 3V3_IN
31.6k
0402
1%
R103
3V3_GOOD
i Power Class
0R 0805
R100
47k
0402
1%
R108
4.7uF
16V
0603
C112
200K
R123
VBAT_OUT
GND
GND
147k
0603
1%
R122
GND
0.1uF
16V
0402
C110
0.1uF
16V
0402
C111
VIN
1
VIN
2
SHDN
3
GND 4 PWRGD
5
CDELAY 6
ADJ 7
VOUT 8
EP 9
MCP1727/0.8V-5V
U102
GND
20k
0603
1%
R125
3V3_REG
4.7uF
16V
0603
C109
10k
0402
5%
R132
1
TP100
1
TP105
GND
0R
0402
DNP
R124
Figure 5-4. 3.3V Regulator for PKOB4
PG_SYSTEM PG_SYSTEM
4.7uF
16V
0603
C115
200K
R126
GND
GND
147k
0603
1%
R128
GND
0.1uF
16V
0402
C114
0.1uF
16V
0402
C116
VIN
1
VIN
2
SHDN
3
GND 4 PWRGD
5
CDELAY 6
ADJ 7
VOUT 8
EP 9
MCP1727/0.8V-5V
U104
GND
20k
0603
1%
R129
5V0
3V3_PKOB
2.2R
1206
1%
R131
4.7uF
16V
0603
C113
0R
0805
R130
10k
0402
5%
R133
1TP101
GND
VDD_GND
GND
TN2106
3
1
2
Q100
3V3_IN
100R
0603
1%
R116
4.7k
0402
1%
R121
VDD bleeder
EV36W50A
Appendix A: Reference Circuit
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 18

Figure 5-5. USB High Speed Hub
220R
FB200
GNDEGND
0.1uF
16V
0201
C217
iPower Class i Power Class
10k
0402
5%
R200
HUB_D_N
HUB_D_P
3V3_PKOB
47k
0402
5%
R202
100k
0402
5%
R201
0.1uF
10V
0402
C202
GND
12k
0402
1%
R209
0.1uF
16V
0402
C201
D_N
D_P
31.6k
0402
1%
DNP R204
D_P
D_N
VBUS_DETECT
USB2_HS
USB_HS
47k
0402
1%
DNP
R205
0.1uF
16V
0402
C203 0.1uF
10V
0402
C204
10000pF
50V
0402
C210
10000pF
50V
0402
C211
10000pF
50V
0402
C212
USB2514B-IM2
USBDM_DN1/PRT_DIS_M1 1
USBDP_DN1/PRT_DIS_P1 2
USBDM_DN2/PRT_DIS_M2 3
USBDP_DN2/PRT_DIS_P2 4
VDDA33
5
USBDM_DN3/PRT_DIS_M3 6
USBDP_DN3/PRT_DIS_P3 7
USBDM_DN4/PRT_DIS_M4 8
USBDP_DN4/PRT_DIS_P4 9
VDDA33
10
TEST
11
PRTPWR1/BC_EN1 12
OCS_N1 13
CRFILT
14
VDD33
15
PRTPWR2/BC_EN2 16
OCS_N2 17
PRTPWR3/BC_EN3 18
OCS_N3 19
PRTPWR4/BC_EN4 20
OCS_N4 21
SDA/SMBDATA/NON_REM1 22
VDD33
23
SCL/SMBCLK/CFG_SEL0 24
HS_IND/CFG_SEL1 25
RESET_N
26 VBUS_DET 27
SUSP_IND/LOCAL/PWR/NON_REM0
28
VDDA33
29
USBDM_UP 30
USBDP_UP 31
XTALOUT
32
XTALIN/CLKIN
33
PLLFILT
34
RBIAS
35
VDDA33
36
EP
37
U201
3V3_PKOB
100k
0402
5%
R210
GND
3V3_PKOB
0.1uF
16V
0402
C213
0.1uF
16V
0402
C214
0.1uF
16V
0402
C215
GND
3V3_PKOB
GND
3V3_PKOB
GND
10000pF
50V
0402
C209
EGND
HUB_D_P
HUB_D_N
ID 4
VBUS 1
GND 5
D- 2
D+ 3
0
J200 i
Power Class
EMI2121MTTAG
In_1+
1
In_1−
2
GND
3
GND
4GND 5
VDD/ID 6
Out_1−7
Out_1+ 8
U200
GND GND GND
0.1uF
16V
0201
C220
GND
GND
3V3_PKOB
STB
1
GND
2OUT 3
VDD 4
Y200
4.7uF
10V
0402
C200
0.1uF
16V
0402
C208
10000pF
50V
0402
C207
GND
10000pF
50V
0402
C218
0.1uF
16V
0402
C219
GND
GND
MCPD_N
MCPD_P
VBUS_DETECT
USB_D+
USB_D-
VBUS
GND
22R 0402R229
22R 0402R230
3V3_PKOB
NMCLR 0R 0402
DNP
R231
0.1uF
16V
0201
C216
3V3_PKOB
100k
0402
5%
R233
100k
0402
5%
DNP
R232
GND
0R 0402 R234 VBUS_WFI32E
0R 0402
DNPR235
PRTPWR_MCP
0R 0402 R206
VBUS_DETECT
GND
47k
0402
5%
R207
47k
0402
5%
DNP
R227
47k
0402
5%
R208
VBUS
CFG_SEL[1:0]=[1:0] for Bus Powered Operation
NON_REM[1:0] = 11: ports 1,2 and 3 are non-removable
Figure 5-6. MCP2200 USB UART Converter
MCPD_P
MCPD_N
VDD
18
VUSB
14
D-
15
D+
16
RST
1
RTS 8
CTS
10
TX
7
RX
9
OSC1
19
OSC2
20
VSS
17
SPND/GP0 13
USBCFG/GP1 12
GP2 11
GP3 6
GP4 5
GP5 4
RXLED/GP6 3
TXLED/GP7 2
PAD
21
MCP2200-I/MQ
U202
MCP2200 QFN-20GND
3V3_PKOB
10k
0402
5%
R203
0.1uF
16V
0402
C205
PRTPWR_MCP
GND
0.1uF
16V
0201
C206
GND
GND
3V3_PKOB
U1TX
U1RX
TP202
TP203
12MHz
2
3 1
X200
0R
0402
R236
PRTPWR_MCP
Figure 5-7. ICSP
330R
0402 1%
R212
330R
0402 1%
R213
330R
0402 1%
R220
330R
0402 1%
R221
MOSI
SCK
MISO
SCK_IN
CLK_EN
DATA_EN
ICSP
ICSP
ICSP_SPI0_SPCK
ICSP_SPI0_MOSI
ICSP_SPI0_MISO
ISP_SPI1_SPCK
ICSP_SPI0_MOSI
ICSP_SPI0_MISO
ICSP_SPI0_SPCK (ICSP_SCK)
(SCK_IN)
(ICSP_SDO)
(ICSP_SDI)
ISP_SPI1_SPCK
DATA_EN
CLK_EN
3.3k
0402
1%
R216
GND
3V3_PKOB 3V3_IN
4.7k
0402
1%
R214
GND
GND
DATA_EN
3V3_PKOB 3V3_IN
4.7k
0402
1%
R223
GND
GND
3.3k
0402
1%
R224
CLK_EN
0.1uF
16V
0201
C224
GND
0.1uF
16V
0201
C221
GND
22R
0402
1%
R211
22R
0402
1%
R219
PGD2/AN5/CVD5/CVDR5/CVDT2/RTCC/RPB5
PGC2/AN4/CVD4/CVDR4/CVDT3/RPB4
0.1uF
16V
0201
C225
GND
0.1uF
16V
0201
C226
GND
DIR
5
A
3B4
GND 2
VCCA
1VCCB 6
74LVC1T45FW4-7
U203
DIR
5
A
3B4
GND 2
VCCA
1VCCB 6
74LVC1T45FW4-7
U204
GND
Buffer voltage range is 1.2V to 5..5V
EV36W50A
Appendix A: Reference Circuit
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 19

Figure 5-8. VPP Switch
GND
IRLML6402
3
12
Q200
GND
GND
VPP_ON
VPP_GND
GND
GND
4.7k
0402
1%
R222
GND
4.7k
0402
1%
R218
4.7k
0402
1%
R215
TN2106
3
1
2
Q201
TN2106
3
1
2
Q202
3V3_IN
NMCLR
10uF
10V
0402
C222
10uF
10V
0402
C223
100R
0402
1%
R217
10k
0402
5%
R237
To Application VPP/MCLR
Figure 5-9. UART
3V3_PKOB
3V3_IN
0.1uF
16V
0201
C227
GND
0.1uF
16V
0201
C230
3V3_PKOB
GND
3V3_IN
22R
0402
1%
R225
22R
0402
1%
R226
ETXD1/CVDT12/RPC14
ETXEN/CVDT11/RPC13
0.1uF
16V
0201
C228
0.1uF
16V
0201
C229
GND
GND
U3RX
U3TX
DIR
5
A
3B4
GND 2
VCCA
1VCCB 6
74LVC1T45FW4-7
U205
GND
DIR
5
A
3B4
GND 2
VCCA
1VCCB 6
74LVC1T45FW4-7
U206
GND
GNDRXD2
TXD2
EV36W50A
Appendix A: Reference Circuit
© 2022 Microchip Technology Inc.
and its subsidiaries
User Guide DS50003262A-page 20