STM STM32WB Application note
AN5378
Application note
STM32WB Series microcontrollers bring-up procedure
Introduction
The STM32WB Series microcontrollers are ultra-low-power devices which embed wireless functions compliant with both the
Bluetooth® Low Energy SIG specification v5.0 and / or IEEE 802.15.4-201. These protocols work on radio frequency which
abbreviates to RF.
The objective of this document is to provide detailed guidelines to optimize the application implementation.
The application is optimized through the following steps:
• Board and environment setup
• Device configuration
• Power supply
• HSE trimming
• Output power test
• Sensitivity test
• Packet exchange test
• Power consumption in advertising mode
• RF tests for certification
• RF tests for production.
This application note uses the NUCLEO-WB55 board, MB1355C, as the reference hardware platform for the configuration. The
configuration settings can then be applied to a custom implementation.
Although this application addresses all the STM32WB Series microcontrollers' wireless functions, the Bluetooth® Low Energy
standard is used as the implementation example for the STM32WB Series microcontrollers' dedicated application. The same
process, however, is used for the IEEE 802.15.4-201 standard implementation.
AN5378 - Rev 2 - May 2020
For further information contact your local STMicroelectronics sales office.
www.st.com
1 General information
This document applies to the STM32WB Series dual-core Arm®-based microcontroller.
Specific examples will be based on STM32WB55 devices but they apply to the whole Series.
Note: Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
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General information
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2 Board setup
The MB1355C NUCLEO-WB55 board is designed around the STM32WB55RG microcontroller in a 68-pin
VFQFPN68 package. This board is included in the P-NUCLEO-WB55 pack with a USB dongle.
The hardware block diagram in Figure 1 illustrates the connection between the MCU and peripherals (ST-LINK/
V2-1, push buttons, LEDs, Arduino™ UNO V3 connector and ST-Morpho connectors).
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Board setup
Figure 1. STM35WB55RG interface block diagram
For the hardware layout and configuration details of the MB1355C board, refer to the Bluetooth® Low Energy and
802.15.4 Nucleo pack based on STM32WB Series microcontrollers user manual (UM2435).
By default, the MB1355C board is configured to output the RF signal through the PCB antenna path. So, C35 is
fitted and C38 not fitted as shown in Figure 2.
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Figure 2. MB1355C antenna configuration
AN5378
Board setup
To perform certain tests, the RF signal has to be directed through the SMA path. In this case, C35 must be
removed and C38 fitted. An SMA board edge connector must also be soldered to J2.
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3 Environment setup
STM32CubeMonitor-RF is a tool to provide a radio performance test environment for the STM32WB Series
microcontrollers. It provides both transmission and reception tests, and PER measurement facilities. Figure 3
illustrates a typical screen representation. This software package is freely available on www.st.com.
Figure 3. STM32CubeMonitor-RF screen illustration
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Environment setup
AN5378 - Rev 2
For a complete description of this tool software, refer to STM32CubeMonitor-RF software tool for wireless
performance measurements (UM2288). The M4 transparent mode firmware must be programmed on the
STM32WB Series microcontroller to use STM32CubeMonitor-RF.
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4 Device configuration
STM32CubeProg is the tool used to program STM32 products and provides a user friendly environment for
programming and validating the device memory through both:
• The debug interface (JTAG and SWD) – Refer to, for example, Multiprotocol wireless 32-bit MCU Arm®A-
based Cortex®-M4 with FPU, Bluetooth® Low-Energy and 802.15.4 radio solution reference manual
(RM0434) for the STM32WB55 devices.
• The bootloader interface (UART, USB DFU, I2C, SPI, and CAN) – Refer to, for example, Multiprotocol
wireless 32-bit MCU Arm®-based Cortex®-M4 with FPU, Bluetooth® Low-Energy and 802.15.4 radio solution
reference manual (RM0434) for the STM32WB55 devices.
The STM32CubeProg interface is illustrated in Figure 4. This software is freely available on www.st.com.
Figure 4. STM32CubeProg interface illustration
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Device configuration
AN5378 - Rev 2
For a complete description of this software tool, refer to STM32CubeProgrammer software description user
manual (UM2237).
For the Bluetooth® Low Energy, the direct test mode (DTM) is used to send instructions through the application
commands interface (ACI) and host commands interface (HCI) to the STM32WB Series microcontroller.
To program the STM32WB Series microcontroller on the MB1355C, follow the procedure ‘How to flash the
wireless coprocessor binary’ described in Getting started with STM32CubeWB for STM32WB Series user manual
(UM2550). The stm32wb5x_BLE_Stack_fw firmware must be flashed in the Arm® Cortex®-M0+ coprocessor
and the STM32WB Series microcontrollers example BLE_TransparentMode must be flashed in the Arm
Cortex®-M4 processor. Refer to Getting started with STM32CubeWB for STM32WB Series user manual
(UM2550) for firmware location.
®
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5 Power supply
Power up the board with the firmware loaded in both the Arm® Cortex®-M0+ (stm32wb5x_BLE_Stack_fw) and
Arm® Cortex®-M4 (BLE_TransparentMode) as described in Section 4 .
Using a multimeter, measure the voltage at the following points (refer to the board schematic for more
information):
• VDD
• VDDA
• VBAT
• VDDSMPS (does not apply to the STM32WBx0)
• VFBSMPS (does not apply to the STM32WBx0)
• VDDRF
• VDDUSB (does not apply to the STM32WBx0).
On the MB1355C, the maximum available voltage is 3.3V due to the embedded level shifters. The VDD, VBAT,
VDDUSB, VDDA and VDDSMPS power supplies by default are connected to a global power supply named
VDD_MCU and the voltage level can be checked at JP2.
More generally, the measured pin voltage must be aligned with the following values if the SMPS is enabled.
AN5378
Power supply
Symbol Parameter Conditions Min Max Unit
VDD Standard operating voltage -
ADC or COMP used
VDDA Analog supply voltage
VBAT Backup operating voltage - 1.55 3.6
VDDSMPS SMPS operating voltage - 1.71 3.6
VFBSMPS SMPS feedback voltage - 1.4 3.6
VDDRF Minimum RF voltage - 1.71 3.6
VDDUSB USB supply voltage
1. STM32WBx0 min = 2V
2. STM32WBx0 not concerned
VREFBUF used 2.4
ADC, COMP, VREFBUF
not used
USB used 3.0 3.6
USB not used 0 3.6
1.71
1.62
0
(1)
3.6
(2)
3.6
V
If the SMPS is disabled, VFBSMPS is connected to VDDSMPS.
For more information on how to use the SMPS on STM32WB Series microcontrollers, refer to Usage of SMPS on
STM32WB Series microcontrollers application note (AN5246).
Note: In the STM32WB Series microcontroller datasheet, the KPI BLE test cases power consumption refers to VDD
but RF static values refer to VDDRF + VDDSMPS.
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