Limitations In Using Audio Features; Usb Otg Fs Port; Stm32L476G-Eval Used As A Usb Device; Stm32L476G-Eval Used As A Usb Host - ST STM32L476ZG User Manual

UM1855
6.7.3

Limitations in using audio features

Due to the share of some terminals of STM32L476ZG by multiple peripherals, the following
limitations apply in using the audio features:
•
If the SAI1_SDA is used as part of the SAI1 port, it cannot be used as the FMC_NWAIT
signal for the NOR flash memory device. However, FMC_NWAIT is not necessary for
operating the NOR flash memory device. More details on FMC_NWAIT are available in
Section 6.22: NOR flash memory
•
If the SAI1 port of STM32L476ZG is used for streaming audio to the WM8994 codec
IC, STM32L476ZG cannot control the motor.
•
If the digital microphones are attached to STM32L476ZG, the LCD glass module
cannot be driven.
6.8

USB OTG FS port

The STM32L476G-EVAL board supports USB OTG full-speed (FS) communication. The
USB OTG connector (CN1) is Micro-AB.
6.8.1

STM32L476G-EVAL used as a USB Device

When a USB Host connection to the Micro-AB USB connector (CN1) of STM32L476G-
EVAL is detected, the STM32L476G-EVAL board starts behaving as a "USB Device".
Depending on the powering capability of the USB host, the board can take power from the
VBUS terminal of CN1. In the board schematic diagrams, the corresponding power voltage
line is called U5V.
this powering option. The JP19 jumper must be left open to prevent STM32L476G-EVAL
from sourcing a 5 V to the VBUS terminal, which would cause conflict with the 5 V sourced
by the USB host. This might happen if the PC6 GPIO is controlled by the software of the
STM32L476ZG such that, it enables the output of the U1 power switch.
6.8.2

STM32L476G-EVAL used as a USB Host

When a USB Device connection to the Micro-AB USB connector (CN1) is detected, the
STM32L476G-EVAL board starts behaving as a "USB Host". It sources 5 V on the VBUS
terminal of the Micro-AB USB connector (CN1) to power the USB Device. For this to
happen, the STM32L476ZG MCU sets the U1 power switch STMPS2151STR to the ON
state. The LD5 green LED marked VBUS indicates that the peripheral is supplied from the
board. The LD6 red LED marked FAULT lights up if overcurrent is detected. The JP19
jumper must be closed to allow the PC6 GPIO to control the U1 power switch.
In any other STM32L476G-EVAL powering option, the JP19 jumper must be open, to avoid
accidental damage caused to an external USB Host.
device.
Section 6.3 provides information on how to set associated jumpers for
UM1855 Rev 6
Hardware layout and configuration
25/80
79