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UM2271
Hardware layout and configuration
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by PB12 port, collecting the PDM interleaved data. These microphones are powered by
MIC_VDD (PH2 of STM32L4R9AI).
The two DFSDM interface signals (clock and data), are also accessible on the STMod+
connector CN1. Before using STMod+, the user must follow the recommendations below:
•
If STMod+ pin 17 is used, SB1 (DOUT) must be disconnected first.
•
If STMod+ pins 18 or 20 are used, MIC_VDD GPIO (PH2) must be activated at high
level first.
10.12 PSRAM
Two PSRAM footprints are supported on the design, both connected to STM32L4R9AI FMC
interface:
•
A 16-Mbit asynchronous PSRAM (U5), using up to A19 address, is soldered by default.
Reference is IS66WV1M16EBLL-55BLI.
•
A 32-Mbit synchronous PSRAM (U6), using up to A20 address, may be used.
Reference is IS66WVC2M16ECLL-7010BLI.
By default, this PSRAM (U6) is exclusive with CAMERA function (due to DCMI_D4
function multiplexed with A20 of MCU). In case CAMERA is used at the same time than
PSRAM, it is possible to change two solder bridges to deactivate A20 on PSRAM (tied
to high, usable density 16 Mbits) and DCMI_D4 is used for CAMERA.
Note:
Limitation: the two PSRAM are not compatible with JP7 setting at +1V8.
See
for possible PSRAM configuration change.
10.13
USB OTG FS
32L4R9IDISCOVERY supports USB OTG FS (full-speed) communication via the USB
Micro-AB connector (CN9) and USB power switch (U16) connected to VBUS. The board
can be powered by this USB connection at 5 V DC with 625 mA current limitation.
A green LED LD6 is lit in one of the following cases:
•
Power switch (U16) is On and 32L4R9IDISCOVERY works as a USB host
•
VBUS is powered by another USB host when 32L4R9IDISCOVERY works as a USB
device.
The red LED LD7 is lit when over-current occurs.
10.13.1 32L4R9IDISCOVERY as USB device
When the board works as a USB device, it can be powered by the 5 V DC VBUS of this USB
OTG FS connection (jumper JP4 pins 5 and 6 must be connected in position U5V). The
green LEDs LD6 VBUS and LD8 PWR are lit on to confirm the 5 V presence.
