Getting started with the digital MEMS microphone expansion ...

IntroductionThe X-NUCLEO-CCA02M2 expansion board has been designed around MP34DT06J digital MEMS microphone.

It is compatible with the ST morpho connector layout and with digital microphone coupon boards such as STEVAL-MIC001V1,STEVAL-MIC002V1 and STEVAL-MIC003V1.

The X-NUCLEO-CCA02M2 embeds two MP34DT06J microphones and allows synchronized acquisition and streaming of up to4 microphones through I²S, SPI, DFSDM or SAI peripherals.

It represents a quick and easy solution for the development of microphone-based applications as well as a starting point foraudio algorithm implementation.

Figure 1. X-NUCLEO-CCA02M2 expansion board

Getting started with the digital MEMS microphone expansion board based on MP34DT06J for STM32 Nucleo

UM2631

User manual

UM2631 - Rev 1 - September 2019For further information contact your local STMicroelectronics sales office.

www.st.com

https://www.st.com/en/product/x-nucleo-cca02m2

https://www.st.com/en/product/mp34dt06j

https://www.st.com/en/product/steval-mic001v1





1 Getting started

1.1 Hardware requirements

The X-NUCLEO-CCA02M2 expansion board can be connected to any STM32 Nucleo board.However, the related firmware, X-CUBE-MEMSMIC1, offers an out-of-the-box package for some STM32 Nucleoboards (for further details, refer to the firmware documentation on www.st.com).

Figure 2. X-NUCLEO-CCA02M2 on STM32 Nucleo board

When mounting the X-NUCLEO-CCA02M2 on the STM32 Nucleo, align all the pins with their correspondingconnector.

Note: Handle the boards carefully during this operation and implement ESD prevention measures to avoid damaging(or bending) the male/female pins, connectors and the expansion board components.

1.2 System requirements

To use the X-NUCLEO-CCA02M2 expansion board you need the same hardware and software resources ofSTM32 Nucleo boards (for details, refer to UM1724 on www.st.com) as well as 40 MB of free space on your harddisk and at least 128 MB of RAM to run the related X-CUBE-MEMSMIC1 firmware package.

UM2631Getting started

UM2631 - Rev 1 page 2/22


https://www.st.com/stm32nucleo

https://www.st.com/en/product/x-cube-memsmic1





https://www.st.com/en/product/x-cube-memsmic1

2 Hardware description

The X-NUCLEO-CCA02M2 allows testing STMicroelectronics digital MEMS microphones: two MP34DT06Jmicrophones are mounted on the board and 6 headers (4 mounted with 2 additional footprints) are available forconnecting additional microphones by connecting digital microphone coupon boards (STEVAL-MIC001V1,STEVAL-MIC002V1 and STEVAL-MIC003V1).The X-NUCLEO-CCA02M2 interfaces with the STM32 Nucleo microcontrollers via the I²S, SPI, DFSDM or SAIperipherals for the synchronized acquisition of up to 4 microphones.The board also provides USB streaming using the STM32 Nucleo microcontroller USB peripheral: a USBconnector is available together with the footprint to mount a dedicated oscillator that can be used to feed the hostMCU through the OSC_IN pin.Solder bridges allows choosing from different options, depending on the number of microphones and the MCUperipherals involved.

Figure 3. Microphone coupon board connected to X-NUCLEO-CCA02M2

2.1 USB connector and power source

The on-board USB connector supports audio streaming to the host PC and can also be used to power the wholesystem up, including the STM32 Nucleo board, by:• closing Jumper J1 on the X-NUCLEO-CCA02M2 expansion board• placing JP5 in position E5 on the STM32 Nucleo board

2.2 Audio acquisition strategy

A digital MEMS microphone can be acquired via different peripherals (SPI, I²S, GPIO, SAI or DFSDM). It requiresan input clock to output a PDM stream at the same frequency of the input clock.The PDM stream is further filtered and decimated for conversion into PCM standard for audio transmission.

UM2631Hardware description

UM2631 - Rev 1 page 3/22











Two different digital MEMS microphones can be connected on the same data line, configuring the first one togenerate valid data on the rising edge of the clock and the other one on the falling edge, by setting the L/R pin ofeach microphone accordingly.On the X-NUCLEO-CCA02M2 expansion board two microphones share the same data line. Depending on theperipherals available on the host MCU, different acquisition methods can be implemented to get microphone dataas further detailed in the following paragraphs.

2.2.1 DFSDM microphone acquisitionThe DFSDM peripheral generates the clock needed by the microphones and reads the data on the rising andfalling edges of each PDM line.The acquired signals become an input to DSFDM filters for hardware filtering and decimation to generatestandard PCM streams.An additional software high pass filtering stage removes any DC offset in the output stream. DMA is used toreduce MCU load.

2.2.2 I²S and SPI microphone acquisitionIn this scenario, I²S peripheral is used for the first and second microphone, while SPI is adopted for the third andfourth one.A precise clock signal is generated by the I²S peripheral while the SPI is configured in slave mode and is fed bythe same timing signal generated by I²S. This clock is then halved by a timer and input to the microphones. TheSPI and I²S peripherals operate at twice the microphone frequency to read the data on both the rising and fallingedges of the microphone clock, thus reading the bits of two microphones each.A software demuxing step separates the signal from the two microphones and allows further software processing;typically PDM to PCM conversion is performed to transform PDM signals in the widely adopted and easy tomanage PCM format.For further information regarding MEMS microphones acquisition and PDM to PCM decimation, refer to AN5027and UM2372 on www.st.com.

Figure 4. General acquisition strategy using I²S and SPI

UM2631Audio acquisition strategy

UM2631 - Rev 1 page 4/22


For single microphone acquisition, the microphone precise clock is generated directly by I²S and one singlemicrophone data line is read by the same peripheral.

2.2.3 SAI microphone acquisitionLike DFSDM, the SAI peripheral with PDM interface is able to generate the precise clock needed by themicrophones and can read the data on the rising and falling edges of each PDM line.Unlike DFSDM, however, SAI cannot convert PDM to PCM in hardware, thus a software step for the conversion isneeded after data acquisition.

2.3 Solder bridge configurations

Several board configurations are possible, depending on the use case.MEMS microphones can be plugged into ST morpho pins, and thus to MCU peripherals, with appropriate solderbridges.Clock routing can also be changed according to specific needs.

2.3.1 Solder bridge functions

Table 1. Solder bridge functions with respect to audio acquisition strategies

Solder bridge Function

SB1 Connects USB DM pin from connector to MCU

SB2 Connects USB DP pin from connector to MCU

SB6 Routes on-board oscillator output to OSC_IN MCU pin

SB7 Connects MEMS clock to MCU timer output channel

SB8 Routes I²S clock to SPI clock

SB9 Merges on-board microphone PDMs to be acquired with one interface

SB10 Connects MIC34 PDM to MCU SPI

SB11 Connects MIC12 PDM to MCU I2S

SB12 Clock from the DFSDM peripheral

SB13 I²S clock from MCU

SB14 Connects I²S clock directly to MIC clock without passing through timer

SB15 Connects I²S clock to MCU timer input channel

SB16 Connects MIC12 PDM to MCU DFSDM

SB17 Connects MIC34 PDM to MCU DFSDM

SB24 Connects MIC34 PDM to MCU SAI

SB25 Connects MIC12 PDM to MCU SAI

SB26 Clock from the SAI peripheral

2.3.1.1 Sample use casesIn this section, we analyze specific use cases together with the corresponding solder bridge configurations basedon the acquisition peripherals involved. Custom setups are also possible for ad-hoc functions.

Note: SB1, SB2, SB6 are reserved for the USB or oscillator pins and are not involved in the audio acquisition process.

2.3.1.1.1 Jumper settings for DFSDM-based systems

1 or 2 microphone acquisition

The clock is generated by DFSDM peripheral and the PDM line of the first and second microphone is routed tothe MCU.

UM2631Solder bridge configurations

UM2631 - Rev 1 page 5/22

Table 2. Solder bridge configuration for 1 or 2 microphone acquisition

Solder bridge Status

SB7 Open

SB8 Open

SB9 Open/closed

SB10 Open

SB11 Open

SB12 Close

SB13 Open

SB14 Open

SB15 Open

SB16 Close

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Open

SB25 Open

SB26 Open

Note: J2 must be placed in position 1-2 for on-board microphone acquisition or 2-3 when using an externalmicrophone while J3 must be left open. When acquiring on-board microphones, close SB9 to acquire both ofthem.

4 microphone acquisition

The PDM line of the third and fourth microphone is also routed to the MCU.

Table 3. Solder bridge configuration for 4 microphone acquisition


SB7 Open

SB8 Open

SB9 Open

SB10 Open

SB11 Open

SB12 Close

SB13 Open

SB14 Open

SB15 Open

SB16 Close

SB17 Close


UM2631 - Rev 1 page 6/22


SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Open

SB25 Open

SB26 Open

Note: J2 and J3 must be placed in position 2-3 for external microphone acquisition.

2.3.1.1.2 Jumper settings for I²S-plus-SPI-based systems


The I²S peripheral is used directly to give the right clock to the microphone and to acquire the same microphone.



SB7 Open

SB8 Open

SB9 Open

SB10 Open

SB11 Closed

SB12 Open

SB13 Closed

SB14 Closed

SB15 Open

SB16 Open

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Open

SB25 Open

SB26 Open

Note: J2 must be placed in position 1-2 for on-board microphone acquisition or 2-3 when using an externalmicrophone, while J3 must be left open. If using external microphones, do not plug anything in M2_EXT header.


UM2631 - Rev 1 page 7/22


The I²S peripheral is used to generate twice the frequency needed by the microphones. In this scenario, the clockis then halved by the timer and routed to the microphones to give them the right clock. I²S therefore reads valuesfrom both edges of the merged PDM lines.



SB7 Closed

SB8 Open

SB9 Open /closed

SB10 Open

SB11 Closed

SB12 Open

SB13 Closed

SB14 Open

SB15 Closed

SB16 Open

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Open

SB25 Open

SB26 Open

Note: J2 must be placed in position 1-2 for on-board microphone acquisition or 2-3 when using external microphones,while J3 must be left open. When acquiring on-board microphones, close SB9 to acquire both of them.4 external microphone acquisitionThe I²S peripheral is used to generate a clock frequency that is twice the frequency needed by the microphones,and SPI is configured in slave mode to use such timing. As in the previous case, the clock is then halved by thetimer and routed to the microphones to give the right clock. I²S and SPI read values from both the edges of themerged PDM lines.


Solder bridges Status

SB7 Closed

SB8 Closed

SB9 Open

SB10 Closed

SB11 Closed

SB12 Open


UM2631 - Rev 1 page 8/22

Solder bridges Status

SB13 Closed

SB14 Open

SB15 Closed

SB16 Open

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Open

SB25 Open

SB26 Open


Note: Other configurations are available, based on the MCU used.

Note: When acquiring 4 microphones using a NUCLEO-F746ZG development board, JP6 jumper on the board mustbe opened.

2.3.1.1.3 Jumper settings for SAI-based systems

1 or 2 microphone acquisition

The clock is generated by SAI peripheral and the PDM line of the first and second microphone is routed to theMCU.

Table 7. Solder bridge configuration for 1 or 2 microphone acquisition


SB7 Open

SB8 Open

SB9 Open/closed

SB10 Open

SB11 Open

SB12 Open

SB13 Open

SB14 Open

SB15 Open

SB16 Open

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open


UM2631 - Rev 1 page 9/22

https://www.st.com/en/product/nucleo-f746zg


SB24 Open

SB25 Closed

SB26 Closed

Note: J2 must be placed in position 1-2 for on-board microphone acquisition or 2-3 when using an externalmicrophone while J3 must be left open. When acquiring on-board microphones, close SB9 to acquire both ofthem.


The PDM line of the third and fourth microphone is also routed to the MCU.



SB7 Open

SB8 Open

SB9 Open/closed

SB10 Open

SB11 Open

SB12 Open

SB13 Open

SB14 Open

SB15 Open

SB16 Open

SB17 Open

SB18 Open

SB19 Open

SB20 Open

SB21 Open

SB24 Closed

SB25 Closed

SB26 Closed



UM2631 - Rev 1 page 10/22

3 NUCLEO-F746ZG support

To connect an X-NUCLEO-CCA02M2 expansion board to a NUCLEO-F746ZG development board, morphoheader connectors must be soldered on the relevant footprint available on the STM32 Nucleo.

Note: For the expansion board, you do not need to solder the whole 2 x 80 pin header but only a pair of 2 x 38 pinstripline connectors.

UM2631NUCLEO-F746ZG support

UM2631 - Rev 1 page 11/22


https://www.st.com/en/product/nucleo-f746zg


4 Connectors

The pin assignments for the Arduino UNO R3 and the ST morpho connectors are shown in Table 9. ST morphoconnectors and Table 10. Arduino connectors respectively.

Table 9. ST morpho connectors

Connector Pin Signal Remarks

CN7

1 MIC_CLKx2 If SB20 is closed

3 MIC_PDM34 If SB20 is closed

6 E5V

12 3V3

16 3V3

18 5V

20 GND

22 GND

24 V_IN

29 OSC_CLK_OUT If SB6 is closed

35 MIC_CLK_NUCLEO If SB12 is closed

CN10


12 OTG_FS_DP_NUCLEO If SB1 is closed

14 OTG_FS_DM_NUCLEO If SB2 is closed











UM2631Connectors

UM2631 - Rev 1 page 12/22

Table 10. Arduino connectors

Connector Pin Signal Remarks

CN6

2 3V3

4 3V3

5 5V

6 GND

7 GND

8 V_IN

CN5




CN9






UM2631Connectors

UM2631 - Rev 1 page 13/22

5 Schematic diagrams

Figure 5. X-NUCLEO-CCA02M2 circuit schematic (1 of 3)

C5

NC (1.5K)

J1

E5V

2GND

D46

5VBUS

D11

3OUT

D-2SB1

NC (100nF)

OTG_FS_DM_NUCLEOOTG_FS_DP_NUCLEO

V_USB

2

3V3

SH27

ID4

GND5

EN1

C3

1

1Vbus

SH49

VDD4

3V3

100nF

R3

V_USB

1

D2

USBLC6-2SC6U1

D1

U2 NC (8MHz)

ON: 5 V Voice -> STM32 Nucleo(stream power from expansion board USB)OFF: 5 V generated on the STM32 Nucleo

8SH3

OSC_CLK_OUT

D34

D23

6SH1

2GND

ESDA7P60-1U1M

NC (15pF)

SB2

0R

USB Mini-B

C42

D+3

STPS160A

USB


2

Open

6

34

6

OTG_FS_DP_NUCLEOOTG_FS_DM_NUCLEO

5

3335

3234

E5V

1921

MIC_LED

37

61

22

SB7

CN8

9

2

262830

3

2425

SB17

SPI1_MOSI

3

17

MIC_CLK

OSC_CLK_OUT

MIC_CLK_x2

HEADER 19x2

78

1416

CN5

2

4

36

4SPI1_MISO

25

u4_LED

MIC_PDM34 MIC_PDM12

MIC_CLK_NUCLEO

35

20

3CN6

R4

CN10

SB14

SB10

1

SB1626

17

36

SPI1_SCK

1

18

3

6

31

4

7

4

18

100

11

SB24

SB21

8

238

2729

CN9

16

2

9

MIC_CLK_x2

SB20

5

SB26

5

38

29

5

24

5

15pF

MIC_CLK_NUCLEO

3

CN7

MIC_CLK_NUCLEO

11

27

MIC_CLK_x2

SPI1_CS

C6

2830

MIC_PDM12

SB15

SB25

7

2

15

10

3133

10

22

14

20

13

37

32

19

7

4

MIC_PDM34

21

1

3

9

5VV_IN

MIC_CLK_x2

SB12

8

15

6

SB13

MIC_CLK_NUCLEOMIC_CLK_x2

SB11

OpenOpen

Open

Close

Close

Close

Close

Open

Open

OpenOpen

Open

Open

Open

Open

Open

Open

17

SB23

12

3V3

1012

SB22

8

HEADER 19x2

23

4

2

385

MIC_PDM34

13

SB8 MIC_PDM34

SB6

1

6

UM2631Schematic diagrams

UM2631 - Rev 1 page 14/22


6

Open

6

GN

D5D

3V3

3CLK

MIC_PDM12_u4

MIC_PD

MIC_CLK

MIC_PDM34_u4

1

MIC_PDM12_OB

2

6

1

6

MIC_PDM12_EXTOpen

SB19

3

MIC_PDM12_OB

MIC_PDM34

MIC_CLK

MIC_PDM12_EXT

MIC_CLK

MIC_PU

1

MIC_PU

2LR

u4_LED

J2

MIC_PDM12_EXT

4

MIC_LED

MIC_PDM34_EXT

HEADER 3X2

1

HEADER 3

SB9

CLK

Mic Source Selector

Additional

Open

2

3 2

5

3V3

3

1VDD

MIC_PDM12_u4

3V3

MIC_PD6

14

4

C7

NCCN1

2

4

2

4

4

3

J3

M2

u4

On-Board (OB)

External (EXT)

5

C2

MIC_LED

GN

D5A

MIC_CLK

1

10K

MIC_PU

NC (HEADER 3x2)

4

MIC_PDM34_OB

MIC_PD

MIC_CLK

DOUT

1uF

M1_EXT_B

5

MIC_PDM34_EXT

MIC_CLK

3

MP34DT06J

GN

D5B

100nF

M1 MP34DT06J

5DG

ND

M2_EXT

6

MIC_PU

8

MIC_PD

3V3

MIC_PDM12_EXT

1uF

1

3

SB18

HEADER 3X2

3

DOUT

5

55

MIC_PU

2

GN

D5A

MIC_PD

M3_EXT

GN

D5C 5C

MIC_PDM34_u4

3V3

MIC_PU

C8

MIC_PDM12_u4

MIC_PDM12_EXT

MIC_PDM34_EXT

R1

MIC_LED

MIC_PDM34_EXT

MIC_CLK

4

MIC_LED

9

NC (HEADER 3x2)

LR2

M4_EXT_A

3

2

R2

VDD

3V3

HEADER 3X2

4

1

3V3

3V3

3V3

10

1

MIC_PDM34_OB

MIC_PDM34_EXT

3V3

HEADER 3MIC_PDM34_OB

5

3

7

100nF

M4_EXT_B

5B

GN

D

C1

MIC_PDM12_OB

GN

D

6

HEADER 3X2

10K

3MIC_LED

2

2

MIC_PDM12

1

MIC_CLK MIC_LED

M1_EXT_A

MIC_PDM34_u4

MIC_CLK

UM2631Schematic diagrams

UM2631 - Rev 1 page 15/22

6 Bill of materials

Table 11. X-NUCLEO-CCA02M2 bill of materials

Item Quantity Reference Part/value Description Manufacturer Order code

1 1 CN1 Stripline M (notmounted) Harwin M52-040023W1045

2 1 CN5 HEADER 10 Stripline F Harwin orequivalent M20-7821046

3 2 CN6, CN9 HEADER 8 Stripline F Harwin orequivalent M20-7820846

4 2 CN7, CN10 HEADER 19x2 Stripline F Samtec ESQ-119-14-G-D

5 1 CN8 HEADER 6 Stripline F Harwin orequivalent M20-7820646

6 3 C1, C2, C5100 nF X7R±10% 0805(2012M)

Ceramic capacitor Murata GCM21BR71H104KA02L

7 1 C315 pF C0G±5% 0805(2012M)

Ceramic capacitor(not mounted) Kemet C0805C150J5GACTU

8 1 C4100 nF X7R±10% 0805(2012M)

Ceramic capacitor(not mounted) Murata GCM21BR71H104KA02L

9 1 C615 pF C0G±5% 0805(2012M)

Ceramic capacitor Kemet C0805C150J5GACTU

10 2 C7, C81 µF X7R±10% 0805(2012M)

Ceramic capacitor Murata GCM219R71C105KA37D

11 1 D1 60 V, 1 A Power Schottkyrectifier ST STPS160A

12 1 D2 ESDA7P60-1U1M

High power transientvoltage suppressor ST ESDA7P60-1U1M

13 1 J1 HEADER 2 Stripline TH 3M 961102-6404-AR

14 2 J2, J3 HEADER 3 Stripline M 3M 961103-6404-AR

15 4

M1_EXT_A, M2_EXT,M3_EXT,M4_EXT_A

HEADER 3X2 3x2 coupon header Harwin M20-7820346

16 2M1_EXT_B,M4_EXT_B

NC (HEADER3x2)

3x2 coupon header(not mounted) Harwin M20-7820346

17 2 M1, M2 MP34DT06J

MEMS audio sensoromnidirectionalstereo digitalmicrophone

ST MP34DT06J

18 2 R1, R210 K 100ppm/°C ±1%0805 (2012M)

SMD resistors TEConnectivity CRG0805F10K

19 1 R31.5 K 100ppm/°C ±1%0805 (2012M)

SMD resistor (notmounted) Vishay CRCW08051K50FKEA

UM2631Bill of materials

UM2631 - Rev 1 page 16/22

https://www.st.com/en/product/stps160

https://www.st.com/en/product/ESDA7P60-1U1M


Item Quantity Reference Part/value Description Manufacturer Order code

20 1 R4100 100ppm/°C ±1%0805 (2012M)

SMD resistor Vishay CRCW0805100RFKEA

21 7

SB1, SB2,SB7, SB9,SB11,SB13,SB15

0 R 100ppm/°C ±1%0603 (1608M)

SMD resistors Vishay CRCW06030000Z0EB

22 16

SB6, SB8,SB10,SB12,SB14,SB16,SB17,SB18,SB19,SB20,SB21,SB22,SB23,SB24,SB25,SB26

0 R 100ppm/°C ±1%0603 (1608M)

SMD resistors (notmounted) Vishay CRCW06030000Z0EB

23 1 USB USB Mini-B USB connector Contact MUSB-5B-2.0-S059 SERIES

24 1 U1 USBLC6-2SC6 ESD protection forhigh speed USB 2.0 ST USBLC6-2SC6

25 1 U2 8 MHz 50 ppm7 x 5 x 1.8 mm

8 MHz oscillator (notmounted) Raltron CO4305-8.000-EXT

26 1 J1 J1 closed Jumper Molex 90059-0007

27 1 J2 J2 - position1-2 Jumper Molex 90059-0008

28 1 J3 J3 off Jumper Molex 90059-0009

UM2631Bill of materials

UM2631 - Rev 1 page 17/22

https://www.st.com/en/product/USBLC6-2

Revision history

Table 12. Document revision history

Date Version Changes

18-Sep-2019 1 Initial release.

UM2631

UM2631 - Rev 1 page 18/22

Contents

1 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

1.1 Hardware requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.1 USB connector and power source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2 Audio acquisition strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2.1 DFSDM microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2.2 I²S and SPI microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2.3 SAI microphone acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Solder bridge configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3.1 Solder bridge functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 NUCLEO-F746ZG support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

4 Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

5 Schematic diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

6 Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

UM2631Contents

UM2631 - Rev 1 page 19/22

List of figuresFigure 1. X-NUCLEO-CCA02M2 expansion board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Figure 2. X-NUCLEO-CCA02M2 on STM32 Nucleo board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Figure 3. Microphone coupon board connected to X-NUCLEO-CCA02M2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Figure 4. General acquisition strategy using I²S and SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Figure 5. X-NUCLEO-CCA02M2 circuit schematic (1 of 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Figure 6. X-NUCLEO-CCA02M2 circuit schematic (2 of 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Figure 7. X-NUCLEO-CCA02M2 circuit schematic (3 of 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

UM2631List of figures

UM2631 - Rev 1 page 20/22

List of tablesTable 1. Solder bridge functions with respect to audio acquisition strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Table 2. Solder bridge configuration for 1 or 2 microphone acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Table 3. Solder bridge configuration for 4 microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Table 4. Solder bridge configuration for 1 microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Table 5. Solder bridge configuration for 2 microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Table 6. Solder bridge configuration for 4 microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Table 7. Solder bridge configuration for 1 or 2 microphone acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Table 8. Solder bridge configuration for 4 microphone acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Table 9. ST morpho connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Table 10. Arduino connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Table 11. X-NUCLEO-CCA02M2 bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Table 12. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

UM2631List of tables

UM2631 - Rev 1 page 21/22

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