Audio; Digital Microphones; Table 6. Digital Microphone-Related Jumper Settings - ST STM32L4R9I-EVAL User Manual

UM2248
WA1: add a delay between sending Write command and its ACK request. Its duration
should be the duration of the 256-Byte Flash write time.
WA2: read back after each write operation (256 bytes or at end of user code flashing) and in
case of error start write again.
WA3: Using bootloader, load a patch code in RAM to write in Flash memory through same
Write Memory write protocol as bootloader (code provided by ST). The patch code is
available for download from
instructions.
9.9

Audio

A codec connected to STM32L4R9AII6 SAI interface supports DSAI port TDM feature. This
offers STM32L4R9AII6 the capability to simultaneously stream two independent stereo
audio channels to two separate stereo analog audio outputs.
There are two digital microphones on STM32L4R9I-EVAL board.
9.9.1

Digital microphones

U30 and U31 on STM32L4R9I-EVAL board are MP34DT01TR MEMS digital omnidirectional
microphones providing PDM (pulse density modulation) outputs. To share the same data
line, their outputs are interlaced. The combined data output of the microphones is directly
routed to STM32L4R9AII6 terminals, thanks to the integrated input digital filters. The
microphones are supplied with programmable clock generated directly by STM32L4R9AII6.
As an option, the microphones is connected to U26, Wolfson audio codec device, WM8994.
In that configuration, U26 also supplies the PDM clock to the microphones.
Regardless of where the microphones are routed to, STM32L4R9AII6 or WM8994, their
power supplier is either VDD or MICBIAS1 output of the WM8994 codec device.
Table 6 shows settings of all jumpers associated with the digital microphones on the board.
Jumper
JP16
JP15
www.st.com

Table 6. Digital microphone-related jumper settings

Setting
PDM clock for digital microphones comes from WM8994 codec.
Default setting.
PDM clock for digital microphones comes from STM32L4R9AII6.
Power supply of digital microphones is generated by WM8994
codec.
Default setting.
Power supply of digital microphones is V
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Hardware layout and configuration
website with a readme.txt file containing usage
Configuration
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