UM1900

Hardware description

DocID027905 Rev 3

9/19

Figure 4: General acquisition strategy using I²S and SPI

For single microphone acquisition, the correct microphone timer is generated directly by I²S

and one single microphone data line is read by the same peripheral.

3.4

Solder bridge configurations

Various board configurations are possible, depending on the use cases. MEMS

microphones can be plugged into ST morpho pins, and thus to MCU peripherals, using ad

hoc solder bridges. Clock routing can also be changed according to specific needs. This

section helps the user understand the role of each solder bridge and analyzes some of the

more common use cases.

3.4.1

Solder bridge roles

In the table below, the solder bridge functions are summarized with respect to the audio

acquisition strategies above.

Table 1: Solder bridge description

Function

Solder Bridge

Connects USB DM pin from connector to MCU

SB1

Connects USB DP pin from connector to MCU

SB2

Routes onboard oscillator output to OSC_IN MCU pin

SB6

Connect MEMS clock to MCU timer output channel

SB7

Routes I²S clock to SPI clock

SB8

Merges onboard microphone PDMs in order to be acquired with 1 interface

SB9