SILICON LABS UG545 EFM32PG28 Pro Kit User Guide

UG545: EFM32PG28 Pro Kit User’s Guide

 LABS UG545 EFM32PG28 Pro Kit

The PG28 Pro Kit is an excellent starting point to become familiar with the EFM32PG28™ Gecko Microcontroller.
The pro kit contains sensors and peripherals demonstrating some of the EFM32PG28’s many capabilities. The kit provides all necessary tools for developing an EFM32PG28 Gecko application.

TARGET DEVICE

• EFM32PG28 Gecko Microcontroller (EFM32PG28B310F1024IM68-A)
• CPU: 32-bit ARM Cortex-M33
• Memory: 1024 kB flash and 256 kB RAM®

KIT FEATURES

• USB connectivity
• Advanced Energy Monitor (AEM)
• SEGGER J-Link on-board debugger
• Debug multiplexer supporting external hardware as well as on-board MCU
• 8×20 segment LCD
• User LEDs and push buttons
• Silicon Labs’ Si7021 Relative Humidity and Temperature Sensor
• SMA connector for IADC demonstration • Inductive LC sensor
• 20-pin 2.54 mm header for expansion boards
• Breakout pads for direct access to I/O pins
• Power sources include USB and CR2032 coin cell battery

SOFTWARE SUPPORT

• Simplicity Studio™
• IAR Embedded Workbench
• Keil MDK

Introduction

1.1 Description
The PG28 Pro Kit is an ideal starting point for application development on the EFM32PG28 Gecko Microcontrollers. The board features sensors and peripherals, demonstrating some of the many capabilities of the EFM32PG28 Gecko Microcontroller. Additionally, the board is a fully featured debugger and energy monitoring tool that can be used with external applications.
1.2 Features

• EFM32PG28 Gecko Microcontroller
• 1024 kB Flash
• 256 kB RAM
• QFN68 package
• Advanced Energy Monitoring system for precise current and voltage tracking
• Integrated Segger J-Link USB debugger/emulator with the possiblity to debug external Silicon Labs devices
• 20-pin expansion header
• Breakout pads for easy access to I/O pins
• Power sources include USB and CR2032 battery
• 8×20 segment LCD
• 2 push buttons and LEDs connected to EFM32 for user interaction
• Silicon Labs’ Si7021 Relative Humidity and Temperature Sensor
• SMA connector for EFM32 IADC demonstration
• External 1.25 V reference for the EFM32 IADC
• LC tank circuit for inductive proximity sensing of metallic objects
• Crystals for LFXO and HFXO: 32.768 kHz and 39.000 MHz

1.3 Getting Started
Detailed instructions for how to get started with your new PG28 Pro Kit can be found on the Silicon Labs Web pages: silabs.com/development- tools

Kit Block Diagram

An overview of the PG28 Pro Kit is shown in the figure below.

Kit Hardware Layout

The PG28 Pro Kit layout is shown below.

Connectors

4.1 Breakout Pads
Most of the EFM32PG28’s GPIO pins are available on the pin header rows at the top and bottom edges of the board. These have a standard 2.54 mm pitch, and pin headers can be soldered in if required. In addition to the I/O pins, connections to power rails and ground are also provided. Note that some of the pins are used for kit peripherals or features and may not be available for a custom application without tradeoffs.
The figure below shows the pinout of the breakout pads and the pinout of the EXP header on the right edge of the board. The EXP header is further explained in the next section. The breakout pad connections are also printed in silkscreen  next to each pin for easy reference.

Figure 4.1. Breakout Pads and Expansion Header
The table below shows the pin connections for the breakout pads. It also shows which kit peripherals or features are connected to the different pins.
Table 4.1. Bottom Row (J101) Pinout

Table 4.2. Top Row (J102) Pinout

4.2 EXP Header
On the right side of the board, an angled 20-pin EXP header is provided to allow connection of peripherals or plugin boards. The connector contains a number of I/O pins that can be used with most of the EFM32PG28 Gecko’s features. Additionally, the VMCU, 3V3, and 5V power rails are also exposed. The connector follows a standard which ensures that commonly used peripherals such as a SPI, UART, and I C bus are available on fixed locations on the connector.
The rest of the pins are used for general purpose I/O. This layout allows the definition of expansion boards that can plug into a number of different Silicon Labs kits. 2 The figure below shows the EXP header pin assignment for the PG28 Pro Kit. Because of limitations in the number of available GPIO pins, some of the EXP header pins are shared with kit features.

4.3 Debug Connector (DBG)
The debug connector serves a dual purpose, based on the debug mode, which can be set up using Simplicity Studio. If the “Debug IN” mode is selected, the connector allows an external debugger to be used with the on-board EFM32PG28. If the “Debug OUT” mode is selected, the connector allows the kit to be used as a debugger towards an external target. If the “Debug MCU” mode (default) is selected, the connector is isolated from the debug interface of both the board controller and the on-board target device. Because this connector is automatically switched to support the different operating modes, it is only available when the board controller is powered (J-Link USB cable connected). If debug access to the target device is required when the board controller is unpowered, this should be done by connecting directly to the appropriate pins on the breakout header. The pinout of the connector follows that of the standard ARM Cortex Debug 19-pin connector. The pinout is described in detail below. Note that even though the connector supports JTAG in addition to Serial Wire Debug, it does not necessarily mean that the kit or the on-board target device supports this.

Even though the pinout matches the pinout of an ARM Cortex Debug connector, these are not fully compatible as pin 7 is physically removed from the Cortex Debug connector. Some cables have a small plug that prevents them from being used when this pin is present. If this is the case, remove the plug, or use a standard 2×10 1.27 mm straight cable instead.
Table 4.4. Debug Connector Pin Descriptions

between target and
debugger.
2| TMS / SDWIO / C2D| JTAG test mode select, Serial Wire data or C2 data
4| TCK / SWCLK / C2CK| JTAG test clock, Serial Wire clock or C2 clock
6| TDO/SWO| JTAG test data out or Serial Wire output
8| TDI / C2Dps| JTAG test data in, or C2D “pin sharing” function
10| RESET / C2CKps| Target device reset, or C2CK “pin sharing” function
12| NC| TRACECLK
14| NC| TRACED0
16| NC| TRACED1
18| NC| TRACED2
20| NC| TRACED3
9| Cable detect| Connect to ground
11, 13| NC| Not connected
3, 5, 15, 17, 19| GND|

4.4 Simplicity Connector
The Simplicity Connector featured on the PG28 Pro Kit enables advanced debugging features such as the AEM and Virtual COM port to be used towards an external target. The pinout is illustrated in the figure below.

The signal names in the figure and the pin description table are referenced from the board controller. This means that VCOM_TX should be connected to the RX pin on the external target, VCOM_RX to the target’s TX pin, VCOM_CTS to the target’s RTS pin, and VCOM_RTS to the target’s CTS pin.
Note: Current drawn from the VMCU voltage pin is included in the AEM measurements, while the 3V3 and 5V voltage pins are not. To monitor the current consumption of an external target with the AEM, put the on-board MCU in its  lowest energy mode to minimize its impact on the measurements.

Table 4.5. Simplicity Connector Pin Descriptions

Power Supply and Reset

5.1 MCU Power Selection
The EFM32PG28 on the pro kit can be powered by one of these sources:

• The debug USB cable
• 3 V coin cell battery

The power source for the MCU is selected with the slide switch in the lower left corner of the pro kit. The figure below shows how the different power sources can be selected with the slide switch.

Figure 5.1. Power Switch
With the switch in the AEM position, a low noise 3.3 V LDO on the pro kit is used to power the EFM32PG28. This LDO is again powered from the debug USB cable. The Advanced Energy Monitor is now connected in series, allowing accurate high-speed current measurements and energy debugging/profiling.
With the switch in the BAT position, a 20 mm coin cell battery in the CR2032 socket can be used to power the device. With the switch in this position, no current measurements are active. This is the recommended switch position when powering the MCU with an external power source.
Note: The Advanced Energy Monitor can only measure the current consumption of the EFM32PG28 when the power selection switch is in the AEM position.
5.2 Board Controller Power
The board controller is responsible for important features, such as the debugger and the AEM, and is powered exclusively through the USB port in the top left corner of the board. This part of the kit resides on a separate power domain, so  a different power source can be selected for the target device while retaining debugging functionality. This power domain is also isolated to prevent current leakage from the target power domain when power to the board controller is  removed.
The board controller power domain is not influenced by the position of the power switch.
The kit has been carefully designed to keep the board controller and the target power domains isolated from each other as one of them powers down. This ensures that the target EFM32PG28 device will continue to operate in the BAT mode.

5.3 EFM32PG28 Reset
The EFM32PG28 MCU can be reset by a few different sources:

• A user pressing the RESET button
• The on-board debugger pulling the #RESET pin low
• An external debugger pulling the #RESET pin low
  In addition to the reset sources mentioned above, a reset to the EFM32PG28 will also be issued during board controller boot-up. This means that removing power to the board controller (unplugging the J-Link USB cable) will not generate a reset but plugging the cable back in will as the board controller boots up.

Peripherals

The pro kit has a set of peripherals that showcase some of the EFM32PG28 features. Note that most EFM32PG28 I/Os routed to peripherals are also routed to the breakout pads or the EXP header, which must be taken into consideration when using these I/Os.
6.1 Push Buttons and LEDs
The kit has two user push buttons marked BTN0 and BTN1. They are connected directly to the EFM32PG28 and are debounced by RC filters with a time constant of 1 ms. The buttons are connected to pins PB1 and PB6.
The kit also features two yellow LEDs marked LED0 and LED1 that are controlled by GPIO pins on the EFM32PG28. The LEDs are connected to pins PC10 and PC11 in an active-high configuration.

6.2 LCD
A 28-pin segment LCD is connected to the EFM32’s LCD peripheral. The LCD has 8 common lines and 20 segment lines, giving a total of 160 segments in octaplex mode. These lines are not shared on the breakout pads. Refer to the kit schematic for information on signals to segments mapping.
A capacitor connected to the EFM32 LCD peripheral’s charge pump pin is also available on the kit.

6.3 Si7021 Relative Humidity and Temperature Sensor
The 2 C relative humidity and temperature sensor is a monolithic CMOS IC integrating humidity and temperature sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I The Si7021 I C Interface. The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and hysteresis, and excellent long term stability. 2 The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This ensures that the sensors are fully interchangeable with no recalibration or software changes required. The Si7021 is available in a 3×3 mm DFN package and is reflow solderable. It can be used as a hardware and software-compatible drop- in upgrade for existing RH/temperature sensors in 3×3 mm DFN-6 packages, featuring precision sensing over a wider range and lower power consumption. The optional factory-installed cover offers a low profile, convenient means of protecting the sensor during assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates. The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew point, and temperature in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms. 2 The I C line. To use the sensor, PA12 must be set high. When enabled, the sensor’s current consumption is included in the AEM measurements. C bus used for the Si7021 is shared with the Expansion Header. The temperature sensor is normally isolated from the I2.

Refer to the Silicon Labs web pages for more information: http://www.silabs.com/humidity-sensors.

6.4 LC Sensor
An inductive-capacitive sensor for demonstrating the Low Energy Sensor Interface (LESENSE) is located on the bottom right of the board. The LESENSE peripheral uses the voltage digital-to-analog converter (VDAC) to set up an oscillating current through the inductor and then uses the analog comparator (ACMP) to measure the oscillation decay time. The oscillation decay time will be affected by the presence of metal objects within a few millimeters of the inductor. The LC sensor can be used for implementing a sensor that wakes up the EFM32PG28 from sleep when a metal object comes close to the inductor, which again can be used as a utility meter pulse counter, door alarm switch, position indicator or other applications where one wants to sense the presence of a metal object.

For more information about the LC sensor usage and operation, refer to the application note, “AN0029: Low Energy Sensor Interface -Inductive Sense”, which is available in Simplicity Studio or in the document library on the Silicon Labs
website.
6.5 IADC SMA Connector
The kit features an SMA connector which is connected to the EFM32PG23˙s IADC through one of the dedicated IADC input pins (AIN0) in a single-ended configuration. The dedicated ADC inputs facilitate optimal connections between external signals and the IADC. The input circuitry between the SMA connector and the ADC pin has been designed to be a good compromise between optimal settling performance at various sampling speeds and protection of the EFM32 in case of an overvoltage situation. If using the IADC in High Accuracy mode with ADC_CLK configured to be higher than 1 MHz, it is beneficial to replace the 549 Ω resistor with 0 Ω. This comes at the cost of reduced overvoltage protection. See the device reference manual for more information about the IADC. 

Note that there is a 49.9 Ω resistor to ground on the SMA connector input which, depending on the output impedance of the source, influences the measurements. The 49.9 Ω resistor has been added to increase the performance towards  50 Ω output impedance sources.

6.6 Virtual COM Port
An asynchronous serial connection to the board controller is provided for application data transfer between a host PC and the target EFM32PG28, which eliminates the need for an external serial port adapter.

The Virtual COM port consists of a physical UART between the target device and the board controller, and a logical function in the board controller that makes the serial port available to the host PC over USB. The UART interface consists  of two pins and an enable signal.
Table 6.1. Virtual COM Port Interface Pins

board controller

Note: The VCOM port is only available when the board controller is powered, which requires the J-Link USB cable to be inserted.

Advanced Energy Monitor

7.1 Usage
The Advanced Energy Monitor (AEM) data is collected by the board controller and can be displayed by the Energy Profiler, available through Simplicity Studio. By using the Energy Profiler, current consumption and voltage can be measured and linked to the actual code running on the EFM32PG28 in realtime.
7.2 Theory of Operation
To accurately measure current ranging from 0.1 µA to 47 mA (114 dB dynamic range), a current sense amplifier is utilized together with a dual gain stage. The current sense amplifier measures the voltage drop over a small series resistor.  The gain stage further amplifies this voltage with two different gain settings to obtain two current ranges. The transition between these two ranges occurs around 250 µA. Digital filtering and averaging is done within the board controller  before the samples are exported to the Energy Profiler application.
During kit startup, an automatic calibration of the AEM is performed, which compensates for the offset error in the sense amplifiers.

7.3 Accuracy and Performance
The AEM is capable of measuring currents in the range of 0.1 µA to 47 mA. For currents above 250 µA, the AEM is accurate within 0.1 mA. When measuring currents below 250 µA, the accuracy increases to 1 µA. Although the absolute accuracy is 1 µA in the sub 250 µA range, the AEM is able to detect changes in the current consumption as small as 100 nA. The AEM produces 6250 current samples per second.

On-Board Debugger

The PG28 Pro Kit contains an integrated debugger, which can be used to download code and debug the EFM32PG28. In addition to programming the EFM32PG28 on the kit, the debugger can also be used to program and debug external  Silicon Labs EFM32, EFM8, EZR32, and EFR32 devices.
The debugger supports three different debug interfaces used with Silicon Labs devices:

• Serial Wire Debug, which is used with all EFM32, EFR32, and EZR32 devices
• JTAG, which can be used with EFR32 and some EFM32 devices
• C2 Debug, which is used with EFM8 devices

To ensure accurate debugging, use the appropriate debug interface for your device. The debug connector on the board supports all three of these modes.

8.1 Debug Modes
To program external devices, use the debug connector to connect to a target board and set the debug mode to [Out]. The same connector can also be used to connect an external debugger to the EFM32PG28 MCU on the kit by setting  debug mode to [In].
Selecting the active debug mode is done in Simplicity Studio. Debug
MCU: In this mode, the on-board debugger is connected to the EFM32PG28 on the kit.

Debug OUT: In this mode, the on-board debugger can be used to debug a supported Silicon Labs device mounted on a custom board.

Debug IN: In this mode, the on-board debugger is disconnected and an external debugger can be connected to debug the EFM32PG28 on the kit.

Note: For “Debug IN” to work, the kit board controller must be powered through the Debug USB connector.

8.2 Debugging During Battery Operation
When the EFM32PG28 is battery-powered and the J-Link USB is still connected, the on-board debug functionality is available. If the USB power is disconnected, the Debug IN mode will stop working.
If debug access is required when the target is running off another energy source, such as a battery, and the board controller is powered down, make direct connections to the GPIOs used for debugging, which are exposed on the breakout pads.

Kit Configuration and Upgrades

The kit configuration dialog in Simplicity Studio allows you to change the J-Link adapter debug mode, upgrade its firmware, and change other configuration settings. To download Simplicity Studio, go to silabs.com/simplicity.
In the main window of the Simplicity Studio’s Launcher perspective, the debug mode and firmware version of the selected J-Link adapter are shown. Click the [Change] link next to any of these settings to open the kit configuration dialog.

9.1 Firmware Upgrades
You can upgrade the kit firmware through Simplicity Studio. Simplicity Studio will automatically check for new updates on startup.
You can also use the kit configuration dialog for manual upgrades. Click the [Browse] button in the [Update Adapter] section to select the correct file ending in .emz. Then, click the [Install Package] button.

Schematics, Assembly Drawings, and BOM

Schematics, assembly drawings, and Bill of Materials (BOM) are available through Simplicity Studio when the kit documentation package has been installed. They are also available from the kit page on the Silicon Labs website:
silabs.com.

Kit Revision History and Errata

11.1 Revision History
The kit revision can be found printed on the box label of the kit, as outlined in the figure below.

11.2 Errata
There are currently no known issues with this kit.

Document Revision History

Revision 0.1
January 2023

• Initial document version

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Disclaimer
Silicon Labs intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software imple- menters using or intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and “Typical” parameters provided can and do vary in different applications. Application examples described  herein are for illustrative purposes only. Silicon Labs reserves the right to make changes without further notice to the product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or  completeness of the included information. Without prior notification, Silicon Labs may update product firmware during the manufacturing process for security or reliability reasons. Such changes will not alter the specifications or the  performance of the product. Silicon Labs shall have no liability for the consequences of use of the infor- mation supplied in this document. This document does not imply or expressly grant any license to design or fabricate any integrated  circuits. The products are not designed or authorized to be used within any FDA Class II devices, applications for which FDA premarket approval is required or Life Support Systems without the specific written consent of Silicon Labs. A  “Life Support System” is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected to result in significant personal injury or death. Silicon Labs products are not designed or  authorized for military applications. Silicon Labs products shall under no circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such  weapons. Silicon Labs disclaims all express and implied warranties and shall not be responsible or liable for any injuries or damages related to use of a Silicon Labs product in such unauthorized applications.
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