DocID022256 Rev 4 17/42
UM1472 Hardware and layout
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4.6 On board audio capability
The STM32F4 uses an audio DAC (CS43L22) to output sounds through the audio mini jack
connector.
The STM32F4 controls the audio DAC through the I2C interface and processes digital
signals through 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 STM32F4.
• The sound can be output in different ways through audio DAC:
– Using I2S protocol
– Using the STM32F4 DAC to analog input AIN1x of the CS43L22
– Using the microphone output directly via a low pass filter to analog input AIN4x of
the CS43L22
4.7 USB OTG supported
The STM32F4 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 connected device
4.8 Motion sensor (ST MEMS LIS302DL or LIS3DSH)
Two different versions of motion sensor (U5 in schematic) are available on the board
depending the PCB version. The LIS302DL is present on board MB997B (PCB revision B)
and the LIS3DSH is present on board MB997C (PCB rev C).
The LIS302DL or LIS3DSH are both an ultra compact low-power three-axis linear
accelerometer.
It includes a sensing element and an IC interface able to provide the measured acceleration
to the external world through I2C/SPI serial interface.
The LIS302DL has dynamically user selectable full scales of +-2g/+-8g and it is capable of
measuring acceleration with an output rate of 100Hz to 400Hz.
The LIS3DSH has ±2g/±4g/±6g/±8g/±16g dynamically selectable full-scale and it is capable
of measuring acceleration with an output data rate of 3.125 Hz to 1.6 kHz.
The STM32F4 controls this motion sensor through the SPI interface.
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