ST STM32L4 Series User manual

March 2018 UM2153 Rev 4 1/57
1
UM2153
User manual
Discovery kit for IoT node, multi-channel communication
with STM32L4
Introduction
The STM32L4 Discovery kit for the IoT node (B-L475E-IOT01A) allows users to develop
applications with direct connection to cloud servers.
The STM32L4 Discovery kit enables a wide diversity of applications by exploiting low-power
multilink communication (BLE, Sub-GHz), multiway sensing (detection, environmental
awareness) and Arm®Cortex®-M4 core-based STM32L4 Series features.
Arduino™ Uno V3 and PMOD connectivity provide unlimited expansion capabilities with a
large choice of specialized add-on boards.
The STM32L4 Discovery kit includes an ST-LINK debugger/programmer and comes with
the comprehensive STM32Cube software libraries together with packaged software
examples to seamlessly connect to cloud servers. In addition a direct access to the Arm®
mbed Enabled™on-line resources at http://mbed.org is available.
Figure 1. B-L475E-IOT01A Discovery kit
1. Picture is not contractual.
www.st.com

Contents UM2153
2/57 UM2153 Rev 4
Contents
1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Product marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Development toolchains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Demonstration software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Hardware layout and configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1 STM32L4 Discovery kit for IoT node layout . . . . . . . . . . . . . . . . . . . . . . . 10
7.2 STM32L4 Discovery kit for IoT node mechanical drawing . . . . . . . . . . . . 12
7.3 Embedded ST-LINK/V2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.3.1 Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.3.2 ST-LINK/V2-1 firmware upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.4 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.5 Programming/debugging when the power supply is not from
ST-LINK (5V_ST_LINK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.6 Clock sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.7 Reset sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.8 USB OTG FS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.9 Quad-SPI NOR Flash memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.10 Virtual COM port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.11 RF modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.11.1 Bluetooth (V4.1 compliant) SPBTLE-RF module . . . . . . . . . . . . . . . . . . 20
7.11.2 Sub-GHz low-power-programmable RF module
(SPSGRF-868 or SPSGRF-915) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.11.3 Wi-Fi module Inventek ISM43362-M3G-L44 (802.11 b/g/n) . . . . . . . . . 22
7.11.4 Dynamic NFC Tag based on M24SR with its printed NFC antenna . . . . 23
7.12 STMicroelectronics sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.12.1 Two on-board ST-MEMS microphones (MP34DT01) . . . . . . . . . . . . . . 24

UM2153 Rev 4 3/57
UM2153 Contents
3
7.12.2 Capacitive digital sensor for relative humidity and
temperature (HTS221) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.12.3 High-performance 3-axis magnetometer (LIS3MDL) . . . . . . . . . . . . . . . 25
7.12.4 3D accelerometer and 3D gyroscope (LSM6DSL) . . . . . . . . . . . . . . . . 26
7.12.5 260-1260 hPa absolute digital output barometer (LPS22HB) . . . . . . . . 26
7.12.6 Time-of-Flight and gesture detection sensor (VL53L0X) . . . . . . . . . . . . 27
7.13 STSAFE-A 100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.14 Buttons and LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.15 I2C addresses of modules used on MB1297 . . . . . . . . . . . . . . . . . . . . . . 29
8 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.1 Arduino Uno V3 connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.2 TAG connector CN5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
8.3 ST-LINK/V2-1 USB Micro-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.4 ST-LINK debug connector CN8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.5 USB OTG FS micro-AB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.6 PMOD connector CN10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.7 Jumper JP5 for IDD measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Appendix A STM32L4 Discovery kit for IoT node I/O assignment . . . . . . . . . . . 37
Appendix B Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Appendix C Board revision history and limitations . . . . . . . . . . . . . . . . . . . . . . 53
Appendix D Federal Communications Commission (FCC)
and Industry Canada (IC) Compliance . . . . . . . . . . . . . . . . . . . . . . . 54
D.1 FCC Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
D.1.1 Part 15.19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
D.1.2 Part 15.105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.7.1 Part 15.21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.8 IC Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.8.1 Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.8.2 Déclaration de conformité . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.8.3 RF exposure statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

List of tables UM2153
4/57 UM2153 Rev 4
List of tables
Table 1. Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 2. Button and LED control port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 3. I2C addresses for each module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 4. Arduino connector pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 5. TAG connector pinout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6. USB Micro-B connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 7. ST-LINK debug connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 8. USB OTG FS Micro-AB pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 9. USB OTG FS power management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 10. PMOD solder bridge configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 11. STM32L4 Discovery kit for IoT node I/O assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 12. Board revision history and limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 13. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

UM2153 Rev 4 5/57
UM2153 List of figures
5
List of figures
Figure 1. B-L475E-IOT01A Discovery kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 2. Hardware block diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 3. STM32L4 Discovery kit for IoT node (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 4. STM32L4 Discovery kit for IoT node (bottom view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 5. STM32L4 Discovery kit for IoT node mechanical drawing . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 6. USB composite device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 7. JP4: 5V_ST_LINK selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 8. JP4: 5V_ARD selection from CN6 (VIN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 9. JP4: 5V_USB_FS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 10. JP4: 5V_VBAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 11. JP4: 5V_USB_CHARGER selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 12. Power tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 13. SPBTLE-RF module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 14. SPSGRF module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 15. ISM43362-M3G-L44 module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 16. Label for Class 1 laser products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 17. Arduino connector (front view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 18. TAG connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 19. TC2050-IDC-NL cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 20. USB Micro-B connector CN7 (front view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 21. USB OTG FS Micro-AB connector CN9 (front view). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 22. STM32L4 Discovery kit for IoT node (top) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 23. STM32L475VG microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 24. STM32L475VG microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 25. USB OTG FS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 26. RF module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 27. ST-MEMS sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 28. NFC and STSAFE part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 29. Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Figure 30. Arduino Uno V3 connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 31. Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Figure 32. ST-LINK/V2-1 with support of SWD only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Features UM2153
6/57 UM2153 Rev 4
1 Features
•Ultra-low-power STM32L4 Series MCUs based on Arm®Cortex®-M4 core with 1 Mbyte
of Flash memory and 128 Kbytes of SRAM, in LQFP100 package
•64-Mbit Quad-SPI (Macronix) Flash memory
•Bluetooth®V4.1 module (SPBTLE-RF)
•Sub-GHz (868 or 915 MHz) low-power-programmable RF module
(SPSGRF-868 or SPSGRF-915)
•Wi-Fi®module Inventek ISM43362-M3G-L44 (802.11 b/g/n compliant)
•Dynamic NFC tag based on M24SR with its printed NFC antenna
•2 digital omnidirectional microphones (MP34DT01)
•Capacitive digital sensor for relative humidity and temperature (HTS221)
•High-performance 3-axis magnetometer (LIS3MDL)
•3D accelerometer and 3D gyroscope (LSM6DSL)
•260-1260 hPa absolute digital output barometer (LPS22HB)
•Time-of-Flight and gesture-detection sensor (VL53L0X)
•2 push-buttons (user and reset)
•USB OTG FS with Micro-AB connector
•Board expansion connectors:
– Arduino™ Uno V3
–PMOD
•Flexible power-supply options: ST-LINK USB VBUS or external sources
•On-board ST-LINK/V2-1 debugger/programmer with USB
re-enumeration capability: mass storage, virtual COM port and debug port
•Comprehensive free software including a
variety of examples, as part of the STM32Cube
package, as well as a cloud connector software expansion, enabling direct access to cloud
servers
•Support of wide choice of Integrated Development Environments (IDEs) including IAR™,
Keil®, GCC-based IDEs, Arm®mbed Enabled™
•Arm®mbed Enabled™(see http://mbed.org)

UM2153 Rev 4 7/57
UM2153 Product marking
56
2 Product marking
Evaluation tools marked as "ES" or "E" are not yet qualified and therefore they are not ready
to be used as reference design or in production. Any consequences deriving from such
usage will not be at ST charge. In no event, ST will be liable for any customer usage of these
engineering sample tools as reference design or in production.
"E" or "ES" marking examples of location:
•On the targeted STM32 that is soldered on the board (for illustration of STM32 marking,
refer to the section “Package characteristics” of the STM32 datasheet at www.st.com).
•Next to the evaluation tool ordering part number, that is stuck or silk-screen printed on
the board.
3 System requirements
•Windows®OS (XP, 7, 8 and 10), Linux®or MacOS™
•USB Type-A to Micro-B cable
4 Development toolchains
•Keil®MDK-Arm(a)
•IAR™EWARM(a)
•GCC-based IDEs including free SW4STM32 from AC6
•Arm®mbed Enabled™online
5 Demonstration software
The demonstration software, included in the STM32Cube package, is preloaded in the
STM32 Flash memory for easy demonstration of the device peripherals in standalone mode.
The latest versions of the demonstration source code and associated documentation can be
downloaded from the www.st.com/stm32app-discovery webpage.
a. On Windows®only.

Ordering information UM2153
8/57 UM2153 Rev 4
6 Ordering information
To order the B-L475E-IOT01A Discovery kit for IoT node, depending on the frequency of the
Sub-GHz module, refer to Table 1.
Table 1. Ordering information
Order code Sub-GHz operating frequency
B-L475E-IOT01A1 915 MHz
B-L475E-IOT01A2 868 MHz

UM2153 Rev 4 9/57
UM2153 Hardware layout and configuration
56
7 Hardware layout and configuration
The STM32L4 Discovery kit for IoT node is designed around the STM32L475VGT6 (100-
pin, LQFP package). The hardware block diagram (see Figure 2) illustrates the connection
between the STM32 and peripherals (embedded ST-LINK, Arduino Uno V3 shields, PMOD
connector, Quad-SPI Flash memory, USB OTG connectors, digital microphones, various
ST-MEMS sensors and the four RF modules (Wi-Fi, Bluetooth, Sub-GHz and NFC)).
Figure 4 and Figure 5 help users to locate these features on the STM32L4 Discovery kit.
Figure 2. Hardware block diagram
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Hardware layout and configuration UM2153 10/57 UM2153 Rev 4
7.1 STM32L4 Discovery kit for IoT node layout
Figure 3. STM32L4 Discovery kit for IoT node (top view)

UM2153 Hardware layout and configuration
UM2153 Rev 4 11/57
Figure 4. STM32L4 Discovery kit for IoT node (bottom view)

Hardware layout and configuration UM2153 12/57 UM2153 Rev 4
7.2 STM32L4 Discovery kit for IoT node mechanical drawing
Figure 5. STM32L4 Discovery kit for IoT node mechanical drawing
1. Plastic Spacer Height = 14mm, Overall Height = 26mm +/- 1mm.

UM2153 Rev 4 13/57
UM2153 Hardware layout and configuration
56
7.3 Embedded ST-LINK/V2-1
The ST-LINK/V2-1 programming and debugging tool is integrated on the STM32L4 Discovery
kit for IoT node. Compared to the ST-LINK/V2 the changes are listed below.
The new features supported on the ST-LINK/V2-1 are:
•USB software re-enumeration
•Virtual COM port interface on USB
•Mass storage interface on USB
•USB power management request for more than 100 mA power on USB
The following features are no more supported on the ST-LINK/V2-1:
•SWIM interface
•Application voltage lower than 3 V
For all general information concerning debugging and programming features common
between V2 and V2-1 versions, refer to ST-LINK/V2 in-circuit debugger/programmer for
STM8 and STM32 User manual (UM1075) at the www.st.com website.
7.3.1 Drivers
Before connecting STM32L475VG to a Windows®PC (XP, 7, 8 or 10) via USB, a driver for
the ST-LINK/V2-1 must be installed. It is available at the www.st.com website.
In case the STM32L4 Discovery kit for IoT node is connected to the PC before the driver is
installed, some STM32L4 Discovery kit interfaces may be declared as “unknown” in the PC
device manager. In this case the user must install the driver files, and update the driver of
the connected device from the device manager (see Figure 6).
Note: Prefer using the “USB Composite Device” handle for a full recovery.
Figure 6. USB composite device

Hardware layout and configuration UM2153
14/57 UM2153 Rev 4
7.3.2 ST-LINK/V2-1 firmware upgrade
The ST-LINK/V2-1 embeds a firmware upgrade mechanism for in-situ upgrade through the
USB port. As the firmware may evolve during the lifetime of the ST-LINK/V2-1 product (for
example new functionalities, bug fixes, support for new microcontroller families), it is
recommended to visit the www.st.com website, before starting to use the STM32L4
Discovery kit for IoT node and periodically, to stay up-to-date with the latest firmware
version.
7.4 Power supply
The STM32L4 Discovery kit for IoT node is designed to be powered by 5 V DC power
supply. It is possible to configure the STM32L4 Discovery kit to use any of the following five
sources for the power supply: 5V_ST_LINK, 5V_ARD, 5V_USB_FS, 5V_VBAT and
5V_USB_CHARGER.
In case of external 5 V DC power adapter, the STM32L4 Discovery kit must be powered by
a power supply unit or by an auxiliary equipment complying with the standard EN-60950-1:
2006+A11/2009, and must be Safety Extra Low Voltage (SELV) with limited power
capability.
•5V_ST_LINK (See Figure 7) is a 5V DC power with limitation from CN7 (the USB type
Micro-B connector of ST-LINK/V2-1). In this case, jumper of JP4 should be on pins 1
and 2 to select the 5V_ST_LINK power source on silkscreen of JP4. This is the default
setting. If the USB enumeration succeeds, the 5V_ST_LINK power is enabled, by
asserting the PWR_ENn signal (from STM32F103CBT6). This pin is connected to a
power switch ST890, which powers the board. This power switch features also a
current limitation to protect the PC in case of a short-circuit on board (more than
750 mA). STM32L4 Discovery kit for IoT node can be powered from the ST-LINK USB
connector CN7, but only ST-LINK circuit has the power before USB enumeration,
because the host PC only provides 100 mA to the board at that time. During the USB
enumeration, STM32L4 Discovery kit for IoT node asks for the 500 mA power to the
host PC. If the host is able to provide the required power, the enumeration finishes by a
“SetConfiguration” command and then, the power transistor ST890 is switched ON, the
red LED LD7 is turned ON, thus the STM32L4 Discovery kit for IoT node consumes up
to 500 mA current, but no more. If the host is not able to provide the requested current,
the enumeration fails. Therefore the ST890 remains OFF and the MCU part including
the extension board is not powered. As a consequence the red LED LD7 remains
turned OFF. In this case it is mandatory to use an external power supply.

UM2153 Rev 4 15/57
UM2153 Hardware layout and configuration
56
Figure 7. JP4: 5V_ST_LINK selection
•5V_ARD (see Figure 8) is the 7 to 12 V DC power from Arduino CN2 pin 8 (named VIN
on Arduino connector silkscreen). In this case, jumper of JP4 should be on pins 3 and 4
to select the 5V_ARD power source on silkscreen of JP4. In that case, the DC power
comes from the power supply through the Arduino Uno V3 battery shield (compatible
with Adafruit PowerBoost 500 Shield).
Figure 8. JP4: 5V_ARD selection from CN6 (VIN)
•5V_USB_FS (see Figure 9) is the DC power with 500 mA limitation from CN9, the USB
OTG FS micro-AB connector. In this case, jumper of JP4 should be on pins 5 and 6 to
select the 5V_USB_FS power source on silkscreen of JP4.
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Hardware layout and configuration UM2153
16/57 UM2153 Rev 4
Figure 9. JP4: 5V_USB_FS
•5V_VBAT (see Figure 10) is the DC power coming from external. In this case, jumper of
JP4 should be on pins 7 and 8 to select the 5V_VBAT power source on silkscreen of
JP4.
Figure 10. JP4: 5V_VBAT
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ST-LINK (CN7). To select the 5V_USB_CHARGER power source on silkscreen of JP4,
the jumper of JP4 should be on pins 9 and 10. In this case, if the STM32L4 Discovery kit
for IoT node is powered by an external USB charger then the debug is not available. If
the PC is connected instead of the charger, the limitation is no longer effective and the
PC could be damaged.
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UM2153 Rev 4 17/57
UM2153 Hardware layout and configuration
56
Figure 11. JP4: 5V_USB_CHARGER selection
Note: If the board is powered by a USB charger, there is no USB enumeration, so the led LD7
remains OFF permanently and the board is not powered. In this specific case only, the
resistor R30 needs to be soldered, to allow the board to be powered anyway.
Caution: Do not connect the PC to the ST-LINK (CN7) when R30 is soldered. The PC may be damaged
or the board may not be powered correctly.
The green LED LD5 is lit when the STM32L4 Discovery kit for IoT node is powered by the 5 V
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Hardware layout and configuration UM2153
18/57 UM2153 Rev 4
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UM2153 Rev 4 19/57
UM2153 Hardware layout and configuration
56
7.5 Programming/debugging when the power supply is not from
ST-LINK (5V_ST_LINK)
It is mandatory to power the board first using CN2 (VIN) or CN9 (USB_FS_OTG), then
connecting the USB cable to the PC. Proceeding this way ensures that the enumeration
succeeds thanks to the external power source.
The following power sequence procedure must be respected:
•Connect the jumper JP4 on (5V_ARD) or (5V_USB_FS)
•Connect the external power source to CN2 in case of an Arduino shield or to CN9 in
case of USB FS host interface
•Check that the red LED LD5 is turned ON
•Connect the PC to USB connector CN7
If this sequence is not respected, the board may be powered by VBUS first from ST-LINK, and
the following risks may be encountered:
•If more than 500 mA current is needed by the board, the PC may be damaged or
current can be limited by PC. As a consequence the board is not powered correctly.
•500 mA is requested at the enumeration, so there is a risk that the request is
rejected
and enumeration does not succeed if the PC cannot provide such current.
7.6 Clock sources
Three clock sources are described below:
•X1 which is the 8 MHz oscillator for STM32L475VG microcontroller. This clock is not
implemented in a basis configuration.
•X2 which is the 32.768 KHz crystal for the STM32L475VG embedded RTC
•X3 which is the 8 MHz clock from ST-LINK MCU for the STM32L475VG microcontroller.
7.7 Reset sources
The reset signal of the STM32L4 Discovery kit is active low and the reset sources includes:
•A reset button B1
•An Arduino Uno V3 shield board from CN2
•An embedded ST-LINK/V2-1
7.8 USB OTG FS
The STM32L4 Discovery kit supports USB OTG FS communication via a USB Micro-AB
connector (CN9).
To do this the following components must be added by the users:
•8 MHz crystal (at X1 position); ref: NX3225GD-8.00M
•8.2 pF capacitor (0402 size) at C2 position
•8.2 pF capacitor (0402 size) at C4 position

Hardware layout and configuration UM2153
20/57 UM2153 Rev 4
•0 ohm resistor (0402 size) at R5 position
•0 ohm resistor (0402 size) at R7 position
The STM32L4 Discovery kit can be powered by the USB connectors at 5 V DC with 500 mA
current limitation.
A USB power switch (IC19) is also connected on VBUS and provides power to CN9. The
green LED LD9 is lit when either:
•Power switch is ON and STM32L4 Discovery kit works as an USB host
•VBUS is powered by another USB host when STM32L4 Discovery kit works as a USB
device.
The red LED LD8 is lit when an over-current occurs.
7.9 Quad-SPI NOR Flash memory
64-Mbit Quad-SPI NOR Flash memory (N25Q128A13EF840F from MICRON) is connected
to the Quad-SPI interface of the STM32L475VGT6.
7.10 Virtual COM port
The serial interface USART1 is directly available as a virtual COM port of the PC connected
to the ST-LINK/V2-1 USB connector CN7. The virtual COM port settings are configured as:
115200 b/s, 8 bits data, no parity, 1 stop bit, no flow control.
7.11 RF modules
Four RF interfaces are available on the STM32L4 Discovery kit for IoT node board:
•Bluetooth (V4.1 compliant) SPBTLE-RF module
•Sub-GHz (868 or 915 MHz) low-power-programmable RF module (SPSGRF-868 or
SPSGRF-915),
•Wi-Fi module Inventek ISM43362-M3G-L44 (802.11 b/g/n compliant)
•Dynamic NFC tag based on M24SR with its printed NFC antenna (double layer
inductive antenna etched on the PCB).
7.11.1 Bluetooth (V4.1 compliant) SPBTLE-RF module
The ST SPBTLE-RF module (M1) is implemented on top side of the STM32L4 Discovery kit
for IoT node board.
The SPBTLE-RF is an easy to use Bluetooth smart master/slave network processor module,
compliant with Bluetooth V4.1. The SPBTLE-RF B-Smart module supports multiple roles
simultaneously, and it can act at the same time as Bluetooth Smart sensor and hub device.
The entire Bluetooth Smart stack and protocol are embedded into the SPBTLE-RF B-Smart
module. The external host application processor, where the application resides, is
connected to the SPBTLE-RF B-Smart module through a standard SPI interface (SPI3 of
STM32L475VGT6).
The SPBTLE-RF B-Smart module provides a complete RF platform in a tiny form factor (foot
print of this module is 13.5 mm x 11.5 mm). Radio, antenna, high frequency and LPO