Stm32L4R9I-Eval Used As A Usb Host; Limitations In Using Usb Otg Fs Port; Operating Voltage; Rs232 Port - ST STM32L4R9I-EVAL User Manual

UM2248
6.10.2

STM32L4R9I-EVAL used as a USB host

When a "USB device" connection to the CN3 Micro-AB USB connector is detected, the
STM32L4R9I-EVAL board starts behaving like a "USB host". It sources 5 V on the V
terminal of the CN3 Micro-AB USB connector to power the USB device. For this to happen,
the STM32L4R9AII6 sets the U2 power switch STMPS2151STR to ON state. The LD6
green LED marked OTG_FS indicates that the peripheral is supplied from the board. The
LD5 red LED marked FS_OC lights up if over-current is detected. The resistor R23 must be
closed to allow the MFX_GPIO6 from MFX MCU to control the U2 power switch.
In any other STM32L4R9I-EVALpowering option, the resistor R23 must be open, to avoid
accidental damage caused to an external USB host.
6.10.3

Limitations in using USB OTG FS port

The USB OTG FS port operation is exclusive with motor control
6.10.4

Operating voltage

The USB-related operating supply voltage of STM32L4R9AII6 (VDD_USB line) must be within
the range from 3.0 V to 3.6 V.
6.11

RS232 port

The STM32L4R9I-EVAL board offers one RS-232 communication port. The RS-232
communication port uses the CN7 DB9 male connector. RX, TX, RTS, and CTS signals of
the STM32L4R9AII6 LPUSART1 interface are routed to CN7.
6.11.1 Operating voltage
The RS-232 operating supply voltage of STM32L4R9AII6 (VDD line) must be within the range
from 1.71 V to 3.6 V.
6.12 microSD™ card
The CN8 slot for microSD™ card is routed to STM32L4R9AII6 SDIO port, accepting SD (up to
2 Gbytes) and SDHC (up to 32 Gbytes) cards. One 8-Gbyte microSD™ card is delivered as
part of STM32L4R9I-EVAL. The card insertion switch is routed to the MFX_GPIO5 of MFX
MCU port.
6.12.1

Limitations

Due to the share of SDIO port, the following limitations apply:
• The microSD™ card cannot be operated simultaneously with motor control.
•
The microSD™ card cannot be operated for 4 bits date when SDIO_D1 and SDIO_D2
used as Trace_D0 and Trace_D1 signals.
6.12.2 Operating voltage
The supply voltage for the STM32L4R9I-EVAL microSD™ card operation must be within the
range from 2.7 V to 3.6 V.
UM2248 Rev 4
Hardware layout and configuration
BUS
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