SILICON LABS BB50 Explorer Kit User Guide

UG550: BB50 Explorer Kit
User’s Guide

BB50 Explorer Kit

The BB50 Explorer Kit is an ultra-low cost, small form factor development and evaluation platform for the EFM8BB50 Busy Bee 8-bit microcontroller.
The BB50 Explorer Kit is focused on rapid prototyping and concept creation of multi-purpose applications. It is designed around the EFM8BB50 MCU, which is an ideal device family for developing energy-friendly embedded applications.
The kit features a USB interface, an on-board SEGGER J-Link debugger, one user-LED and button, and support for hardware add-on boards via a mikroBUS™ socket and a Qwiic® connector. The hardware add-on support allows developers to create and prototype applications using a virtually endless combination of off-the-shelf boards from mikroE, sparkfun, AdaFruit, and Seeed Studios.
TARGET DEVICE

• EFM8BB50 Busy Bee 8-bit microcontroller (EFM8BB50F16I-A-QFN16)
• Pipelined 8-bit C8051 core with 50 MHz maximum operating frequency
• 16 kB flash and 512 bytes RAM

KIT FEATURES

• User LED and push button
• 2.54 mm breakout pads
• mikroBUS™ socket
• Qwiic® connector
• SEGGER J-Link on-board debugger
• Virtual COM port
• USB-powered

SOFTWARE SUPPORT

• Simplicity Studio™

ORDERING INFORMATION

• BB50-EK2702A

Introduction

The BB50 Explorer Kit has been designed to inspire customers to explore the Silicon Labs EFM8BB50 Busy Bee 8-bit microcontroller. The kit includes a mikroBUS™ socket and Qwiic® connector, allowing users to add features to the kit with a large selection of off-theshelf boards.
Programming the BB50 Explorer Kit is easily done using a USB Micro-B cable and the on-board J-Link debugger. A USB virtual COM port provides a serial connection to the target application. The BB50 Explorer Kit is supported in Simplicity Studio™ and a Board Support Package (BSP) is provided to give application developers a flying start.
Connecting external hardware to the BB50 Explorer Kit can be done using the breakout pads which present peripherals from the EFM8BB50 Busy Bee such as I C, SPI, UART, and GPIOs. The mikroBUS socket allows inserting mikroBUS add-on boards which interface with the EFM8BB50 through SPI, UART, or I 2 C. The Qwiic connector can be used to connect hardware from the Qwiic Connect System through I 2 2 C.
1.1 Kit Contents
The following items are included in the box:

• 1x BB50 Explorer Kit board (BRD2702A)

1.2 Getting Started
Detailed instructions for how to get started with your new BB50 Explorer Kit can be found on the Silicon Labs web pages:
silabs.com/dev-tools
1.3 Hardware Content
The following key hardware elements are included on the BB50 Explorer Kit:

• EFM8BB50 Busy Bee MCU with 50 MHz operating frequency, 16 kB flash, and 512 bytes RAM
• One LED and one push button
• On-board SEGGER J-Link debugger for easy programming and debugging, which includes a USB virtual COM port
• MikroBUS™ socket for connecting Click boards™ and other mikroBUS add-on boards
• Qwiic® connector for connecting Qwiic Connect System hardware
• Breakout pads for GPIO access and connection to external hardware
• Reset button

1.4 Kit Hardware Layout
The layout of the BB50 Explorer Kit is shown below.

Specifications

2.1 Recommended Operating Conditions

1. Not recommended for use with rechargeable Lithium batteries. Most Li-Ion and Li-Po cells exceed 3.6 V when fully charged.
2. When using the provided interfaces with add-on boards or other external hardware, tighter voltage limits might apply.

2.2 Current Consumption
The operating current of the board greatly depends on the application and the amount of external hardware connected. The table below attempts to give some indication of typical current consumptions for the EFM8BB50 and the on-board debugger. Note that the numbers are taken from the data sheets for the devices. For a full overview of the conditions that apply for a specific number from a data sheet, the reader is encouraged to read the specific data sheet.
Table 2.1. Current Consumption

MCU current consumption in SNOOZE mode (module supply voltage = 3.3 V, LFOSC running at 80 kHz, TAMB 25 ˚C)| 9.3| µA
MCU current consumption in SHUTDOWN mode (module supply voltage = 3.3 V, TAMB 25 ˚C)| 0.24| µA
On-board Debugger Sleep Current Consumption 2| IDBG| On-board debugger current consumption when USB cable is not inserted (EFM32GG12 EM4S mode current con- sumption)| 80| nA

1. From EFM8BB50 data sheet.
2. From EFM32GG12 data sheet.

Hardware

The core of the BB50 Explorer Kit is the EFM8BB50 Busy Bee 8-bit microcontroller. Refer to section 1.4 Kit Hardware Layout for placement and layout of the hardware components.
3.1 Block Diagram
An overview of the BB50 Explorer Kit is illustrated in the figure below.

3.2 Power Supply
The kit is powered by the debug USB cable as illustrated in the figure below.

The 5 volt power net on the USB bus is regulated down to 3.3 V using a low dropout regulator (LDO). An automatic isolation circuit isolates the LDO when the USB cable is not plugged in.
Power can be injected externally on the VMCU net if the USB cable is removed and no other power sources are present on the kit.
Failure to follow this guideline can cause power conflicts and damage the LDO.
3.3 EFM8BB50 Reset
The EFM8BB50 can be reset by a few different sources:

• A user pressing the RESET button.
• The on-board debugger pulling the #RESET pin low.

3.4 Push Button and LED
The kit has one user push button, marked BTN0, that is connected to a GPIO on the EFM8BB50. The button is connected to pin P0.7 and it is debounced by an RC filter with a time constant of 1 ms. The logic state of the button is high while the button is not being pressed, and low when the button is pressed.
The kit also features one yellow LED, marked LED0, that is controlled by a GPIO pin on the EFM8BB50. The LED is connected to pin P1.2 in an active-high configuration.

3.5 On-board Debugger
The BB50 Explorer Kit contains a microcontroller separate from the EFM8BB50 Busy Bee that provides the user with an on-board JLink debugger through the USB Micro-B port. This microcontroller is referred to as the “on-board debugger”, and is not programmable by the user. When the USB cable is removed, the on-board debugger goes into a very low power shutoff mode (EM4S).
In addition to providing code download and debug features, the on-board debugger also presents a virtual COM port for general purpose application serial data transfer. The figure below shows the connections between the target EFM8BB50 device and the
on-board debugger.
The figure also shows the presence of the Mini Simplicity Connector, and how this is connected to the same I/O pins. Refer to chapter 4. Debugging for more details on debugging.

3.6 Connectors
The BB50 Explorer Kit features a USB Micro-B connector, breakout pads, a mikroBUS connector for connecting mikroBUS add-on boards, and a Qwiic connector for connecting Qwiic Connect System hardware. The connectors are placed on the top side of the board, and their placement and pinout are shown in the figure below. For additional information on the connectors, see the following sub chapters.

3.6.1 Breakout Pads
Seventeen breakout pads are provided and allow connection of external peripherals. The breakout pads are arranged in two rows and contain a number of I/O pins that can be used with most of the EFM8BB50 Busy Bee’s features. Additionally, the VMCU (main board power rail), 3V3 (LDO regulator output), and 5V power rails are also exposed on the pads.
The pin-routing on the Busy Bee is flexible, so most peripherals can be routed to any pin on port 1 or 2. However, pins may be shared between the breakout pads and other functions on the BB50 Explorer Kit. The figure in section 3.6 Connectors includes an overview of the breakout pads and functionality that is shared with the kit.
Table 3.1. Breakout Pads Pinout

Left-side Breakout Pins
1| GND| Ground
2| 5V| Board USB voltage
3| P1.0| MikroBUS I2C_SDA, Qwiic I2C_SDA
4| P1.1| MikroBUS I2C_SCL, Qwiic I2C_SCL
5| P0.4| VCOM_TX, MicroBUS UART_TX
6| P0.5| VCOM_RX, MicroBUS UART_RX
7| P0.6| MikroBUS INT
8| P1.2| LED0, MikroBUS PWM
Right-side Breakout Pins
1| RSTb| EFM8BB50 reset, active low
2| GND| Ground
3| VMCU| EFM8BB50 voltage domain
4| P0.2| MikroBUS SPI_COPI
5| P0.1| MikroBUS SPI_CIPO
6| P0.0| MikroBUS SPI_SCK
7| P0.3| MikroBUS SPI_CS
8| P2.0| DBG C2D
9| P0.7| BUTTON0, MikroBUS Analog

3.6.2 MikroBUS Socket
The BB50 Explorer Kit features a mikroBUS™ socket compatible with mikroBUS add-on boards. MikroBUS add-on boards can expand the functionality of the kit with peripherals such as sensors and LCDs. Add-on boards follow the mikroBUS socket pin mapping, and communicate with the on-kit EFM8BB50 through UART, SPI, or I C. Several GPIOs are exposed on the mikroBUS socket. MikroBUS add-on boards can be powered by the 5V or VMCU power rails, which are available on the mikroBUS socket.
The pinout of the EFM8BB50 on the kit is made such that all required peripherals are available on the mikroBUS socket. The I2 C signals are, however, shared with the Qwiic connector, and all mikroBUS signals are also routed to adjacent breakout
pads.
When inserting a mikroBUS add-on board, refer to the orientation notch on the BB50 Explorer Kit, shown in the figure below, to ensure correct orientation. Add-on boards have a similar notch that needs to be lined up with the one shown below.

The table below gives an overview of the mikroBUS socket pin connections to the EFM8BB50.
Table 3.2. mikroBUS Socket Pinout

mikro- BUS Pin Name| mikroBUS Pin Function| Connection| Shared Feature| Suggested Peripheral Mapping
---|---|---|---|---
AN| Analog| P0.7| BREAKOUT_RIGHT9| ADC0.CH1
RST| Reset| P2.0| BREAKOUT_RIGHT8|
CS| SPI Chip Select| P0.3| BREAKOUT_RIGHT7| SPI0.NSS
SCK| SPI Clock| P0.0| BREAKOUT_RIGHT6| SPI0.SCK
MISO| SPI Main Input Secondary Output| P0.1| BREAKOUT_RIGHT5| SPI0.CIPO
MOSI| SPI Main Output Secondary Input| P0.2| BREAKOUT_RIGHT4| SPI0.COPI
PWM| PWM output| P1.2| BREAKOUT_LEFT8| TIMERx.Tx
INT| Hardware Interrupt| P0.6| BREAKOUT_LEFT7|
RX| UART Receive| P0.5| VCOM_RX, BREAKOUT_LEFT6| UARTx.RX
TX| UART Transmit| P0.4| VCOM_TX, BREAKOUT_LEFT5| UARTx.TX
SCL| I2C Clock| P1.1| QWIIC_I2C_SCL, BREAKOUT_LEFT4| SMB0.SCL
SDA| I2C Data| P1.0| QWIIC_I2C_SDA, BREAKOUT_LEFT3| SMB0.SDA
mikro- BUS Pin Name| mikroBUS Pin Function| Connection| Shared Feature| Suggested Peripheral Mapping
---|---|---|---|---
3V3| VCC 3.3V power| VMCU| EFM8BB50 voltage domain| —
5V| VCC 5V power| 5V| Board USB voltage| —
GND| Reference Ground| GND| Ground| —

3.6.3 Qwiic Connector
The BB50 Explorer Kit features a Qwiic® connector compatible with Qwiic Connect System hardware. The Qwiic connector provides an
easy way to expand the functionality of the BB50 Explorer Kit with sensors, LCDs, and other peripherals over the I2 C interface. The
Qwiic connector is a 4-pin polarized JST connector, which ensures the cable is inserted the right way.
Qwiic Connect System hardware is daisy chain-able as long as each I2 C device in the chain has a unique I2 C address.
Note: The Qwiic I2 C connections on the BB50 Explorer Kit are shared with the mikroBUS I2 C signals.
The Qwiic connector and its connections to Qwiic cables and the EFM8BB50 are illustrated in the figure below.

The table below gives an overview of the Qwiic connections to the EFM8BB50.
Table 3.3. Qwiic Connector Pinout

Qwiic Pin| Connection| Shared Feature| Suggested Peripheral Mapping
---|---|---|---
Ground| GND| Ground| —
3.3V| VMCU| EFM8BB50 voltage domain| —
SDA| P1.0| MIKROE_I2C_SDA, BREAKOUT_LEFT3| SMB0.SDA
SCL| P1.1| MIKROE_I2C_SCL, BREAKOUT_LEFT4| SMB0.SCL

3.6.4 Debug USB Micro-B Connector
The debug USB port can be used for uploading code, debugging, and as a virtual COM port. More information is available in section

Debugging

The BB50 Explorer Kit contains an on-board SEGGER J-Link Debugger that is connected to the C2 debugging interface on the EFM8BB50. The debugger allows the user to download code and debug applications running in the target EFM8BB50. Additionally, it also provides a virtual COM port (VCOM) to the host computer that is connected to the target device’s serial port for general purpose communication between the running application and the host computer. The on-board debugger is accessible through the USB Micro-B connector.
4.1 On-board Debugger
The on-board debugger is a SEGGER J-Link debugger running on an EFM32 Giant Gecko. The debugger is directly connected to the debug and VCOM pins of the target EFM8BB50.
When the debug USB cable is inserted, the on-board debugger is automatically active, and takes control of the debug and VCOM interfaces. This means that debug and communication will not work with an external debugger connected at the same time. The
on-board LDO is also activated, providing power to the board.
When the USB cable is removed, the board might still be running on external power, as described in section 3.2 Power Supply. In this case, the on-board debugger goes into a very low power shutoff  ode (EM4S), consuming about 80 nA.
4.2 Virtual COM Port
The virtual COM port is a connection to a UART of the target EFM8BB50 and allows serial data to be sent and received from the device. The on-board debugger presents the target UART as a virtual COM port on the host computer that shows up when the USB cable is inserted.
Data is transferred between the host computer and the debugger through the USB connection, which emulates a serial port using the USB Communication Device Class (CDC). From the debugger, the data is passed on to the target device through a physical UART connection.
The serial format is 115200 bps, 8 bits, no parity, and 1 stop bit by default.
Note: Changing the baud rate for the COM port on the PC side does not influence the UART baud rate between the debugger and the target device.

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

6.1 Revision History
The kit revision can be found printed on the box label of the kit, as outlined in the figure below. The kit revision history is summarized in the table below.
EFM8BB50 Explorer Kit

Table 6.1. Kit Revision History

6.2 Errata
There are no known errata at present.

Board Revision History and Errata

7.1 Revision History
The board revision can be found laser printed on the board, and the board revision history is summarized in the following table.
Table 7.1. Board Revision History

7.2 Errata
There are no known errata at present.

Document Revision History

Revision 1.0
June 2023

• Initial document release.

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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 implementers 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 reliabilit y reasons. Such changes will not alter the specifi cations or the per formance of the product. Silicon Labs shall have no liabilit y for the consequences of use of the information 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 III 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.
Note: This content may contain off ensive terminolog y that is now obsolete. Silicon Labs is replacing these terms with inclusive language wherever possible. For more information, visit www.silabs.com/about-us /inclusive-lexicon-project
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References

• Silicon Labs
• Development Tools - Silicon Labs
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• Development Tools - Silicon Labs

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