UM2153 datasheet(14/57 Pages) STMICROELECTRONICS

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Hardware layout and configuration

UM2153

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DocID030118 Rev 3

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 Datenblatt(PDF) 14 Page - STMicroelectronics