ST STM32F401 Discovery User manual

September 2013 DocID025174 Rev 1 1/39
UM1669
User manual
Discovery kit for STM32F401 line
Introduction
The STM32F401 Discovery kit (32F401CDISCOVERY) helps you to discover the entry level
of the STM32F4 series and to develop your applications. It is based on an
STM32F401VCT6 and includes an ST-LINK/V2 embedded debug tool interface, ST MEMS
Gyroscope, ST MEMS accelerometer + magnetometer, ST MEMS digital microphone, audio
DAC with integrated class D speaker driver, LEDs, pushbuttons and a USB OTG micro-AB
connector.
Figure 1. STM32F401 Discovery board
www.st.com

Contents UM1669
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Contents
1 Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Quick start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Development toolchain supporting the STM32F401 Discovery kit . . . . . . . 7
2.4 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Hardware layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1 STM32F401VCT6 microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Embedded ST-LINK/V2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2.1 Using ST-LINK/V2 to program/debug the STM32F401 on board . . . . . 16
4.2.2 Using ST-LINK/V2 to program/debug an external STM32 application . . 17
4.3 Power supply and power selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4 LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.5 Pushbuttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.6 On board audio capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.7 USB OTG supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.8 E-compass MEMS (ST MEMS LSM303DLHC) . . . . . . . . . . . . . . . . . . . . 19
4.9 Gyroscope MEMS (ST MEMS L3GD20) . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.10 JP2 (Idd) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.11 OSC clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.11.1 OSC clock supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.11.2 OSC 32 KHz clock supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.12 Solder bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.13 Extension connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5 Mechanical drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6 Electrical schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

List of tables UM1669
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List of tables
Table 1. ON/OFF conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 2. Features and benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 3. Jumper states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 4. Debug connector CN2 (SWD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 5. Solder bridges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 6. MCU pin description versus board function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 7. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

DocID025174 Rev 1 5/39
UM1669 List of figures
5
List of figures
Figure 1. STM32F401 Discovery board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 1. Hardware block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 2. Top layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 3. Bottom layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 4. STM32F401VCT6 microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 5. STM32F401VCT6 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 6. Typical configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 7. STM32F401 Discovery board connections image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 8. ST-Link connections image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 9. STM32F401 Discovery board mechanical drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 10. STM32F401 Discovery board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 11. ST-LINK/V2 (SWD only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 12. STM32F401VCT6 MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 13. Audio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 14. USB_OTG_FS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 15. Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Conventions UM1669
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1 Conventions
Table 1 provides the definition of some conventions used in the present document.
Table 1. ON/OFF conventions
Convention Definition
Jumper JPx ON Jumper fitted
Jumper JPx OFF Jumper not fitted
Solder bridge SBx ON SBx connections closed by solder
Solder bridge SBx OFF SBx connections left open

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2 Quick start
The STM32F401 Discovery is a low-cost and easy-to-use development kit to quickly
evaluate and start a development with an STM32F4 entry level microcontroller.
Before installing and using the product, please accept the Evaluation Product License
Agreement from www.st.com/stm32f4-discovery.
For more information on the STM32F401 Discovery board and for demonstration software,
visit www.st.com/stm32f4-discovery.
2.1 Getting started
Follow the sequence below to configure the STM32F401 Discovery board and launch the
DISCOVER application:
1. Ensure that the jumpers JP2 and CN3 are set to "on" (Discovery mode).
2. Connect the STM32F401 Discovery board to a PC using a USB cable type A/mini-B
through the USB ST-LINK connector CN1, to power the board. The LED LD2 (PWR)
will light up and the four LEDs between the buttons B1 and B2 start blinking.
3. Press the user button B1 to enable the MEMS sensor. The four LEDs will indicate the
board motion direction and speed. When connected to a PC with a second USB type
A/micro-B cable through CN5, the board will be recognized as a standard mouse.
4. The demo software, as well as other software examples that allow you to discover the
STM32 F4 series features, are available on www.st.com/stm32f4-discovery.
5. Develop your own applications starting from the examples.
2.2 System requirements
•Windows PC (XP, Vista, 7)
•USB type A to mini-B cable
2.3 Development toolchain supporting the STM32F401
Discovery kit
•Altium: TASKING™ VX-Toolset
•Atollic: TrueSTUDIO
•IAR: EWARM
•Keil™: MDK-ARM
2.4 Order code
To order the STM32F401 Discovery kit, use the STM32F401C-DISCO order code.

Features UM1669
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3 Features
The STM32F401 Discovery board offers the following features:
•STM32F401VCT6 microcontroller featuring 256 KB of Flash memory, 64 KB of RAM in
an LQFP100 package
•On-board ST-LINK/V2 with selection mode switch to use the kit as a standalone ST-
LINK/V2 (with SWD connector for programming and debugging)
•Board power supply: through USB bus or from an external 5 V supply voltage
•External application power supply: 3 V and 5 V
•L3GD20, ST MEMS motion sensor, 3-axis digital output gyroscope.
•LSM303DLHC, ST MEMS system-in-package featuring a 3D digital linear acceleration
sensor and a 3D digital magnetic sensor.
•MP45DT02, ST MEMS audio sensor, omnidirectional digital microphone
•CS43L22, audio DAC with integrated class D speaker driver
•Eight LEDs:
– LD1 (red/green) for USB communication
– LD2 (red) for 3.3 V power on
– Four user LEDs:
LD3 (orange), LD4 (green), LD5 (red) and LD6 (blue)
– Two USB OTG LEDs:
LD7 (green) VBus and LD8 (red) over-current
•Two pushbuttons (user and reset)
•USB OTG with micro-AB connector
•Extension header for LQFP100 I/Os for a quick connection to the prototyping board
and an easy probing

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4 Hardware layout
The STM32F401 Discovery board has been designed around the STM32F401VCT6
microcontroller in a 100-pin LQFP package.
Figure 1 illustrates the connections between the STM32F401VCT6 and its peripherals (ST-
LINK/V2, pushbutton, LED, Audio DAC, USB, ST MEMS gyroscope, ST MEMS
accelerometer + magnetometer, ST MEMS microphone, and connectors).
Figure 2 and Figure 3 help you to locate these features on the STM32F401 Discovery
board.
Figure 1. Hardware block diagram
Embedded
ST-LINK/V2
STM32F401VCT6
I/O I/O
I/O RESET
LEDs
LD3...LD8
MP45DT02
B2
RESET
B1
USER
L3GD20
Micro-USB
Mini-USB
SWD
Header
Header
CS43L22
Mini-Jack
MS31947V2
LSM303DLHC

Hardware layout UM1669
10/39 DocID025174 Rev 1
Figure 2. Top layout
MS32361V1
ST-LINK/V2
ST-LINK/V
2
LD1 (red/green LED)
COM
CN2
SWD connector
LD2 (red LED)
PWR
CN3
ST-LINK/DISCOVERY selector
STM32F401VCT6
LD3 (orange LED)
LD5 (red LED)
B2 reset button
LD8 (red LED)LD7 (green LED)
LD6 (blue LED)
LD4 (green LED)
B1 user button
JP2
IDD measurement
SB1 (B2-RESET)
5 V power supply input/output
3 V power supply output

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Figure 3. Bottom layout
MS32362V1
SB3, SB5, SB7, SB9
(DEFAULT) SB10, SB11 (RX, TX)
SB2, SB4, SB6, SB8
(RESERVED)
SB15 (SWO)
SB16 (X2 crystal)
SB17 (X3 crystal)
SB18 (X3 crystal)
SB19 (BOOT0)
SB12 (STM_RST)
SB14 (X2 crystal)
SB13 (NRST)
SB20 (BOOT1)
SB21 (B1-USER)

Hardware layout UM1669
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4.1 STM32F401VCT6 microcontroller
This ARM Cortex-M4 32-bit MCU with FPU has 105 DMIPS, up to 256 KB Flash/64 KB
RAM, USB OTG FS, 10 TIMs, 1 ADC, 11 comm. interfaces.
Figure 4. STM32F401VCT6 microcontroller
This device provides the following benefits (see Table 2).
MS32365V1
STM32F401VCT6
256 Kbytes of Flash memory
64 Kbytes of RAM
LQFP100 14 x 14 mm
Table 2. Features and benefits
Features Benefits
High performance
– Up to 84 MHz/105 DMIPS Cortex-M4 with single cycle
DSP MAC and floating point unit
– CoreMark: 285 at 84 MHz
– CoreMark/MHz:3.39
– Boosted execution of control algorithms
– More features for your applications
– Ease of use
– Better code efficiency
– Faster time to market
– Elimination of scaling and saturation
– Easier support for meta-language tools
Maximum integration
– Up to 256 kB of on-chip Flash, 64k B of SRAM, reset
circuit, internal RCs, PLLs, ultra-small packages
(WLCSP)
More features in space-constrained applications
Designed for high performance and ultra-fast data
transfers
– ART Accelerator™: memory accelerator
Performance equivalent to zero-wait execution from
Flash
– 32-bit 7-layer bus matrix with 6 masters and 5 slaves
including 1 block of SRAM
– Multi DMA controllers: 2 general-purpose
Concurrent execution and data transfer
Outstanding power efficiency
– Ultra-low dynamic power in Run mode: 140 µA/MHz at
84 MHz running CoreMark benchmark from Flash
memory (peripherals off)
– RTC <1 µA typ in VBAT mode
– Down to 11 µA typ in Stop mode
– 3.6 V down to 1.7 V VDD
– 1.2 V voltage regulator with power scaling capability
Extra flexibility to reduce power consumption for
applications requiring both high-processing and low-
power performance when running at low voltage or on a
rechargeable battery

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Superior and innovative peripherals and
connectivity
– 1x USB OTG
– Up to 11 communication interfaces (including
3x USART, 4x SPI, 3x I2C with digital filter, 1 SDIO)
– USART at up to 10.5 Mbit/s
– SPI at up to 42 Mbit/s
New possibilities to connect and communicate high-
speed data
Audio:
– dedicated audio PLL, 2x I2SHigh-quality audio support
Analog:
– 1 x 12-bit ADC reaching 2.4 MSPS
– Up to 10 timers: 16 and 32 bits running up to 84 MHz
More precision thanks to high resolution
High integration
– WLCSP49 3 x 3 mm (STM32F401, 256-Kbyte Flash/
64-Kbyte SRAM)
Smaller board space allowing for smaller applications
Extensive tools and software solutions
– Hardware sector protection with execute only access
– Various IDE, starter kits, libraries, RTOS and stacks,
either open source or provided by ST or 3rd parties,
including the ARM CMSIS DSP library optimized for
Cortex-M4 instructions
– Software IP protection
– A wide choice within the STM32 ecosystem to develop
your applications
Table 2. Features and benefits (continued)
Features Benefits

Hardware layout UM1669
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Figure 5. STM32F401VCT6 block diagram
GPIO PORT A
AHB/APB2
EXT IT. WKUP
up to 81 AF
PA[15:0]
TIM1 / PWM
4 compl. channels TIM1_CH1[1:4]N,
4 channels TIM1_CH1[1:4]ETR,
BKIN as AF
USART1
RX, TX, CK,
CTS, RTS as AF
SPI1
MOSI, MISO,
SCK, NSS as AF
APB2 60MHz
APB1 30MHz
16 analog inputs
VDDREF_ADC
MOSI/SD, MISO/SD_ext, SCK/CK
NSS/WS, MCK as AF
SP3/I2S3
ALARM_OUT
OSC32_IN
OSC32_OUT
VDDA, VSSA
NRST
smcard
irDA
16b
VBAT = 1.65 to 3.6 V
DMA2
SCL, SDA, SMBA as AF
I2C3/SMBUS
JTAG & SW
ARM Cortex-M4
84 MHz
NVIC
ETM
MPU
TRACECLK
TRACED[3:0]
DMA2
8 Streams
FIFO
ACCEL/
CACHE
AHB1 84 MHz
USART 2MBps
Temperature sensor
ADC1 IF
@VDDA
POR/PDR
BOR
Supply
supervision
@VDDA
PVD
Int
POR
reset
XTAL 32 kHz
MANAGT
RTC
RC HS
RC LS
PWR
interface
WDG 32K
@VBAT
@VDDA
@VDD
AWU
Reset &
clock
control
PLL1&2
APB2CLK
VDD = 1.7 to 3.6 V
VSS
VCAP
Voltage
regulator
3.3 to 1.2 V
VDD Power managmt
@VDD
STAMP1
Backup register
AHB bus-matrix 7S4M
APB2 84 MHz
LS
TIM9
2 channels as AF
Flash
up to
256 KB
TIM2
TIM3
TIM4
TIM5
D-BUS
MS31144V2
FPU
APB1 42 MHz (max)
AHB2 84 MHz
NJTRST, JTDI,
JTCK/SWCLK
JTDO/SWD, JTDO
I-BUS
S-BUS
DMA1
8 Streams
FIFO
PB[15:0]
PC[15:0]
PH[1:0]
GPIO PORT B
GPIO PORT C
GPIO PORT H
16b
TIM10
16b
TIM11
16b
smcard
irDA
USART6
1 channel as AF
1 channel as AF
RX, TX, CK as AF
I2C2/SMBUS
I2C1/SMBUS
SCL, SDA, SMBA as AF
SCL, SDA, SMBA as AF
SP2/I2S2
MOSI/SD, MISO/SD_ext, SCK/CK
NSS/WS, MCK as AF
RX, TX as AF
CTS, RTS as AF
USART2
smcard
irDA
32b
16b
16b
32b
4 channels
4 channels, ETR as AF
4 channels, ETR as AF
4 channels, ETR as AF
DMA1
AHB/APB1
LS
OSC_IN
OSC_OUT
HCLK
XTAL OSC
4- 16MHz
SRAM 64 KB
WWDG
APB1CLK
AHB1PCLK
AHB2PCLK
CRC
(PDR OFF)
1.8 to 3.6 V
(PDR ON)
SDIO / MMC
FIFO
D[7:0]
CMD, CK as AF
USB
OTG FS
FIFO
PHY
DP
DM
ID, VBUS, SOF
SPI4
MOSI, MISO,
SCK, NSS as AF
PD[15:0]
GPIO PORT D
PE[15:0]
GPIO PORT E

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4.2 Embedded ST-LINK/V2
The ST-LINK/V2 programming and debugging tool is integrated on the STM32F401
Discovery board. The embedded ST-LINK/V2 can be used in 2 different ways according to
the jumper states (see Table 3 ):
•Program/debug the MCU on board,
•Program/debug an MCU in an external application board using a cable connected to
SWD connector CN2.
The embedded ST-LINK/V2 supports only SWD for STM32 devices. For information about
debugging and programming features, refer to user manual UM1075 (ST-LINK/V2 in-circuit
debugger/programmer for STM8 and STM32) which describes in detail all the ST-LINK/V2
features.
Figure 6. Typical configuration
Table 3. Jumper states
Jumper state Description
Both CN3 jumpers ON ST-LINK/V2 functions enabled for on board programming (default)
Both CN3 jumpers OFF ST-LINK/V2 functions enabled for application through external
CN2 connector (SWD supported)
MS31115V1
Hardware requirements:
- USB cable type A to mini-B
- Computer with Windows XP, Vista or 7
Development toolchains:
- Altium TASKING VX-Toolset
- Atollic TrueSTUDIO
- IAR EWARM
- Keil MDK-ARM

Hardware layout UM1669
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4.2.1 Using ST-LINK/V2 to program/debug the STM32F401 on board
To program the STM32F401 on board, simply plug in the two jumpers on CN3, as shown in
Figure 7 in red, but do not use the CN2 connector as that could disturb communication with
the STM32F401VCT6 of the STM32F401 Discovery board.
Figure 7. STM32F401 Discovery board connections image

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4.2.2 Using ST-LINK/V2 to program/debug an external STM32 application
It is very easy to use the ST-LINK/V2 to program the STM32 on an external application.
Simply remove the 2 jumpers from CN3 as shown in Figure 8, and connect your application
to the CN2 debug connector according to Table 4.
Note: SB13 must be OFF if you use CN2 pin 5 in your external application.
Figure 8. ST-Link connections image
Table 4. Debug connector CN2 (SWD)
Pin CN2 Designation
1 VDD_TARGET VDD from application
2 SWCLK SWD clock
3 GND Ground
4 SWDIO SWD data input/output
5 NRST RESET of target MCU
6 SWO Reserved

Hardware layout UM1669
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4.3 Power supply and power selection
The power supply is provided either by the host PC through the USB cable, or by an
external 5 V power supply.
The D1 and D2 diodes protect the 5 V and 3 V pins from external power supplies:
•5 V and 3 V can be used as output power supplies when another application board is
connected to pins P1 and P2.
In this case, the 5 V and 3 V pins deliver a 5 V or 3 V power supply and the power
consumption must be lower than 100 mA.
•5 V can also be used as input power supplies, e.g. when the USB connector is not
connected to the PC.
In this case, the STM32F401 Discovery board must be powered by a power supply unit
or by an auxiliary equipment complying with standard EN-60950-1: 2006+A11/2009,
and must be Safety Extra Low Voltage (SELV) with limited power capability.
4.4 LEDs
•LD1 COM:
LD1 default status is red. LD1 turns to green to indicate that communications are in
progress between the PC and the ST-LINK/V2.
•LD2 PWR:
The red LED indicates that the board is powered.
•User LD3:
The orange LED is a user LED connected to the I/O PD13 of the STM32F401VCT6.
•User LD4:
The green LED is a user LED connected to the I/O PD12 of the STM32F401VCT6.
•User LD5:
The red LED is a user LED connected to the I/O PD14 of the STM32F401VCT6.
•User LD6:
The blue LED is a user LED connected to the I/O PD15 of the STM32F401VCT6.
•USB LD7:
The green LED indicates when VBUS is present on CN5 and is connected to PA9 of
the STM32F401VCT6.
•USB LD8:
The red LED indicates an overcurrent from VBUS of CN5 and is connected to the I/O
PD5 of the STM32F401VCT6.
4.5 Pushbuttons
•B1 USER:
User and Wake-Up button connected to the I/O PA0 of the STM32F401VCT6.
•B2 RESET:
The pushbutton connected to NRST is used to RESET the STM32F401VCT6.

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4.6 On board audio capability
The STM32F401 uses an audio DAC (CS43L22) to output sounds through the audio mini
jack connector.
The STM32F401 controls the audio DAC through the I2C interface and processes digital
signals through an I2S connection or analog input signal.
•The sound can come independently from different inputs:
– ST MEMS microphone (MP45DT02): digital using PDM protocol or analog when
using the low pass filter.
– USB connector: from external mass storage such as a USB key, USB HDD, and
so on.
– Internal memory of the STM32F401.
•The sound can be output in different ways through audio DAC:
– Using the I2S protocol
– Using the microphone output directly via a low pass filter to analog input AIN4x of
the CS43L22
4.7 USB OTG supported
The STM32F401 is used to drive only USB OTG full speed on this board. The USB micro-
AB connector (CN5) allows the user to connect a host or device component, such as a USB
key, mouse, and so on.
Two LEDs are dedicated to this module:
•LD7 (green LED) indicates when VBUS is active
•LD8 (red LED) indicates an overcurrent from a connected device.
4.8 E-compass MEMS (ST MEMS LSM303DLHC)
The LSM303DLHC is an ultra-compact low-power system-in-package featuring a 3D digital
linear acceleration sensor and a 3D digital magnetic sensor. It includes a sensing element
and an IC interface able to provide the measured acceleration to the external world through
an I2C serial interface.
The LSM303DLHC has dynamically user-selectable full scales of ± 2g/± 8g and is capable
of measuring the acceleration, and a magnetic field full scale from ±1.3 g to 8.1 g with an
output data rate of 100 Hz or 400 Hz.
The STM32F401VCT6 MCU controls this motion sensor through the I2C interface.
4.9 Gyroscope MEMS (ST MEMS L3GD20)
The L3GD20 is an ultra-compact, low-power, three-axis angular rate sensor. It includes a
sensing element and an IC interface able to provide the measured angular rate to the
external world through the I2C/SPI serial interface.
The L3GD20 has dynamically user-selectable full scales of ± 250 dps/500 dps/±2000 dps
and is capable of measuring rates.

Hardware layout UM1669
20/39 DocID025174 Rev 1
The STM32F401VCT6 MCU controls this motion sensor through the SPI interface.
4.10 JP2 (Idd)
Jumper JP2, labeled Idd, allows the consumption of STM32F401VCT6 to be measured by
removing the jumper and connecting an ammeter.
•Jumper on: STM32F401VCT6 is powered (default).
•Jumper off: an ammeter must be connected to measure the STM32F401VCT6 current,
(if there is no ammeter, the STM32F401VCT6 is not powered).
4.11 OSC clock
4.11.1 OSC clock supply
If PH0 and PH1 are only used as GPIOs instead of as a clock, then SB14 and SB16 are
closed and R24, R25 and R66 are removed.
MCO from ST-LINK (from MCO of the STM32F103)
This frequency cannot be changed, it is fixed at 8 MHz and connected to PH0-OSC_IN of
the STM32F401VCT6. The configuration needed is:
– SB14, SB16 OPEN
– R25 removed
– R66 soldered
Oscillator onboard (from X2 crystal)
For typical frequencies and its capacitors and resistors, please refer to the
STM32F401VCT6 Datasheet. The configuration needed is:
– SB14, SB16 OPEN
– R25 soldered
– R66 removed
Oscillator from external PH0 (from external oscillator through pin 7 of the P2 connector)
The configuration needed is:
– SB14 closed
– SB16 closed
– R25 and R66 removed
4.11.2 OSC 32 KHz clock supply
If PC14 and PC15 are only used as GPIOs instead of as a clock, then SB17 and SB18 are
closed, and R21 and R22 are removed.
Oscillator onboard (from X1 Crystal (not provided))
The configuration needed is:
– SB17, SB18 OPEN
– C20, C28, R21 and R22 soldered