ST Microelectronics WESU1 User Manual
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USER MANUAL
Evaluation Board
STEVAL-WESU1
Introduction
The STEVAL-WESU1 is a System Evaluation Board designed to provide a cost effective solution
for precise motion sensing in wearable applications. The system is featuring a low power ARM
Cortex-M3 microcontroller unit (STM32L151), an iNEMO inertial module (LSM6DS3), a high
performance magnetometer (LIS3MDL), a barometric pressure sensor (LPS25HB), a Bluetooth®
low energy wireless network processor (BLUENRG-MS) and power management circuitry that
allows fast charging and precise energy estimation (STNS01 and STC3115). The connectivity
granted by the best in class BLUENRG-MS and supported by the integrated balun (BALF-NRG01D3) permit to maximize the RF performances with low area occupancy and design effort and
pass the RF Test for FCC certification (FCC ID: S9NWESU1) and IC certification (IC ID: 8976CWESU1).
An Android and iOS APP, available on Google Play and Apple Store, can be used for displaying
information sent by the STEVAL-WESU1 through BLE connectivity as well as for setting operative
modes.
Figure 1. STEVAL-WESU1 evaluation board
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Table of Contents
1 Board Description and Getting started ................................................................................... 4
1.1 Getting started ........................................................................................................................ 5
2 Hardware description ............................................................................................................... 8
2.1 Microcontroller ........................................................................................................................ 8
2.2 Sensors .................................................................................................................................. 8
2.2.1 LSM6DS3 ............................................................................................................................... 8
2.2.2 LISM3DL ................................................................................................................................ 8
2.2.3 LPS25HB ................................................................................................................................ 9
2.3 BLUENRG-MS and BALF-NRG-01D3 ................................................................................... 9
2.4 Power management ............................................................................................................... 9
2.4.1 STNS01 and STLQ015 .......................................................................................................... 9
2.4.2 STC3115 .............................................................................................................................. 10
2.5 Connectors ........................................................................................................................... 10
2.5.1 Battery connector ................................................................................................................. 10
2.5.2 SWD Connector and external peripherals............................................................................ 11
2.5.3 USB Connector .................................................................................................................... 12
2.5.4 Exposed pad connector ....................................................................................................... 12
2.5.5 uFL connector ...................................................................................................................... 12
2.6 Buttons and LEDs ................................................................................................................ 12
3 Formal notices required by the U.S. Federal Communications Commission ("FCC") ....... 13
4 Formal notices required by the Industry Canada ("IC") ....................................................... 14
5 Board schematic and bill of material ..................................................................................... 15
5.1 Bill of material ....................................................................................................................... 15
5.2 Schematic ............................................................................................................................. 19
6 Revision history ...................................................................................................................... 20
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1 Board Description and Getting started
The STEVAL-WESU1 is a System Evaluation Board designed and optimized in order to be a
reference design for users would made their own wearable electronic devices. In fact, the system
architecture is made up of hardware, firmware and software solutions to accelerate the overall
development of all applications: from embedded end-customer devices to mobile software
development. The design choices have been taken to address accurate motion tracking suitable
for training in every kind of activity or sport.
Main Components:
- STM32L151VEY6, ultra-low-power ARM Cortex-M3 MCU with 512 Kbytes FLASH, 48kBytes of
RAM in WLCSP100 package
- BLUENRG-MS, Bluetooth Low Energy (BLE) single-mode network processor, compliant with
Bluetooth specification core 4.0
- BALF-NRG-01D3, 50 Ω balun for BLUENRG-MS transceiver with integrated harmonic filter
- LSM6DS3, iNEMO inertial module 3D accelerometer (±2/4/8g) + 3D gyroscope
(±245/500/2000dps)
- LIS3MDL, MEMS 3D magnetometer (±4/8/12/16 gauss)
- LPS25HB, MEMS pressure sensor, 260-1260 hPa absolute digital output barometer
- STC3115, Gas gauge IC with alarm output
- STNS01, Li-Ion linear battery charger
- STLQ015XG30R, linear voltage regulator
The Figure 2 shows a function block diagram of the board where the sensors and the BLUENRGMS are connected to microcontroller through two separate SPI peripherals, meanwhile the power
management is driven by I2C peripheral. The system can be powered with USB connected to PC
or through specific battery. The USB is also used for battery recharge. Figure 3 shows the block
diagram of the RFIC BLUENRG-MS.
Figure 2. Functional Block Diagram
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Figure 3. Block Diagram of RFIC: BlueNRG-MS
1.1 Getting started
The system is delivered fully assembled and connected with battery and with LDO off (shipment
mode, with 2uA power consumption).
It can be simply switched ON with USB-powered cable insertion (micro B male plug). The USB
port connector can be used for battery charging.
The system takes up to 160mA (@5V) to recharge the battery; for this reason you can use both
USB wall adapter and PC port with this capability. Two LEDs (LED1 and LED2, see Figure 3)
describes the Application Status and the Battery Charging Status.
The Charging LED (LED 2) could be:
- Light ON, the USB plug is correctly connected and the board is charging;
- Light OFF, the board is not charging (use USB cable reconnection to force re-start);
- Blinking (approximately at 1Hz), charging failure (e.g. over-temperature, three wires battery not
connected);
It is important to avoid deep discharge (< 30%) to maintain battery integrity and to prevent longterm malfunctioning.
The User Button (see Figure 4) can be pressed to enter and exit the Stop MODE.
At power on the Application LED (LED1) starts with one smooth blink and in normal operation it
blinks at 2s interval; after BLUENRG-MS connection the blinking interval becomes 1s and
STEVAL-WESU1 system reads sensors data and sends it to a Bluetooth Smart Ready device; the
data is displayed using a dedicated App.
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A custom (1.27 mm pitch) SWD connector is used to have a compact solution, since to program
the on-board STM32L151 it has been included in the package a specific adapter useful to be
connected to a programmer tool (e.g. ST-LINK/v2).
Figure 4. Board Layout – top layer
Figure 5. Board Layout – Bottom layer
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Once it has been verified the battery is enough charged, the board is ready to be used. To
visualize the information sent through the Bluetooth Low Energy connectivity is
fundamental to install one of the App available for the Smartphone and Tablet:
- ST WESU Android App, available on Google Play;
- ST WESU iOS App available on Apple Store.
To use this App is need a Smartphone or Tablet supporting the BLE connectivity, i.e.
iPhone 4S and subsequent or, an Android based device with Android OS 4.3 or higher.
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