STMicroelectronics X-NUCLEO-AMICAM1 User Manual

UM2649

User manual

Getting started with the X-NUCLEO-AMICAM1 analog MEMS microphone

expansion board based on MP23ABS1 for STM32 Nucleo

Introduction

The X-NUCLEO-AMICAM1 expansion board allows synchronized acquisition and streaming of up to 4 microphones at a maximum sampling rate of 192 KHz.

It represents a quick and easy solution to develop microphone-based applications and start implementing audio algorithms.

The expansion board is designed around the MP23ABS1 analog MEMS microphone and is compatible with the ST morpho connector layout and with analog microphone coupon boards (e.g., STEV

The X-NUCLEO-AMICAM1 embeds three MP23ABS1 microphones: two connected to an external ADC and one directly routed to the STM32 embedded ADC.

The analog amplification stage is achieved thanks to ST TSV91x wide bandwidth operational amplifiers.

Figure 1. X-NUCLEO-AMICAM1 expansion board

AL-MIC004V1).

UM2649 - Rev 1 - December 2019 For further information contact your local STMicroelectronics sales of

fice.

www.st.com

1 Overview

High bandwidth Op

MP23ABS1

Microphone

External

Ext MIC

I2S

Analog

TSV91x

Internal

High bandwidth Op

DFSDM

Microphone

MP23ABS1

Analog

Microphone

Analog

Amp

TSV91x

MP23ABS1

High bandwidth Op

ADC

Amp

connector

TSV91x

Amp

TSV91x

Amp

TSV91x

ADC

SPI

USB

Sensing

Connectivity

Amp

Processing

Ext MIC

connector

Ext MIC

connector

Ext MIC

connector

Ext MIC

connector

The X-NUCLEO-AMICAM1 expansion board is a comprehensive tool designed for the evaluation of MP23ABS1 analog MEMS microphones.

It features:

•

3 on-board MP23ABS1 analog MEMS microphones

• 5 slots to plug analog microphone coupon boards (e.g., STEVAL-MIC004V1)

• Synchronized acquisition and streaming of up to 4 microphones

• Amplification stage based on TSV91x wide bandwidth operational amplifiers

• On-board external ADC

• Direct acquisition of a single microphone exploiting STM32 embedded ADC

• Up to 192 KHz sampling frequency

• Free comprehensive development firmware library and audio capture plus USB streaming sample application compatible with STM32Cube

• Compatible with STM32 Nucleo boards

• Equipped with ST morpho connectors (top and bottom) and Arduino UNO R3 connectors (top) to allow stacking of multiple boards

• RoHS and WEEE compliant

The X-NUCLEO-AMICAM1 expansion board implements an amplification stage for each microphone, based on TSV91x operational amplifiers, and allows microphone recording using either a dedicated third-party external analog to digital converter, mounted on-board, or the embedded STM32 ADC.

Three microphones are mounted on the X-NUCLEO-AMICAM1 expansion board: 2 of them (M1OB, M2OB) are connected to the external ADC while the third one (M3OB) is directly connected to STM32 embedded ADC.

Five additional headers are available for external analog microphone coupon boards (e.g. STEVAL-MIC004V1). The external ADC is controlled through a SPI interface.

The expansion board provides also USB streaming using the STM32 Nucleo microcontroller USB peripheral; a USB connector is available for data and power supply.

Solder bridges allow choosing from different options, depending on the number of microphones and the MCU peripherals involved.

UM2649

Overview

UM2649 - Rev 1

Figure 2. X-NUCLEO-AMICAM1 expansion board block diagram

page 2/17

2 Hardware description

R1

A2V5

R2

INTREF_BUFF

M1

R3

R4

R5

C1

M1+

INTREF_BUFF (1.25 V)

UM2649

Hardware description

Two different solutions are implemented on the X-NUCLEO-AMICAM1 evaluation in different scenarios:

• a low power and low cost solution using STM32 embedded ADC and TSV912 operational amplifier

• the use of a third party external ADC and TSV914 amplifier

Acoustic quality, power consumption hardware requirements (power supply and amplification circuits) differ on the basis of the chosen solution.

expansion board to allow MP23ABS1

2.1 Amplification stage and signal acquisition - internal ADC

The STM32 analog to digital converter is used in single ended configuration: the microphone signal, in this case, is amplified around a common mode which is equal to half the VREF provided to the STM32 analog supply input (for further details on the power scheme, see Figure 5. X-NUCLEO-AMICAM1 expansion board: power supply

scheme).

Figure 3. X-NUCLEO-AMICAM1 expansion board: amplification of a single microphone

The first operational amplifier is used as a buffer for the bias signal generated by a voltage divider (with R1 equal

to R2); the second one adds a gain equal to

ADC.

Depending on the STM32 Nucleo development board, different ADC configurations are possible, enabling several acquisition strategies which may include oversampling, filtering and decimation using DFSDM hardware peripheral to gain in SNR and bit depth.

R4

1 +

to the microphone signal which is then routed to the STM32

R3

2.2 Amplification stage and signal acquisition - external ADC

UM2649 - Rev 1

The adopted third party analog to digital converter has a differential interface: the microphone amplification stage performs both gain addition and single to dif

ferential conversion to exploit the ADC dynamics.

page 3/17

M1+

M1-

COMM

M1

R1

R2

R3

R4

R5

C1

UM2649

Power scheme

Figure 4. X-NUCLEO-AMICAM1 expansion board: amplification and conversion to differential

R2

1 +

The first operational amplifier adds a gain equal to

configuration with R3 equal to R4, simply adds a phase shift of 180 degrees to the amplified signal.

The COMM represents the bias provided by the external ADC, which is controlled by an SPI interface, and microphone data are acquired by the STM32 through an I²S interface.

, while the second one, configured in inverting

R1

2.3 Power scheme

Power scheme is designed to provide separate supplies to the critical analog parts, which you can find on both the X-NUCLEO-AMICAM1 and the STM32 Nucleo boards.

UM2649 - Rev 1

page 4/17

Figure 5. X-NUCLEO-AMICAM1 expansion board: power supply scheme

USB

X-NUCLEO-AMICAM1

U1

3.0 LDO

U5V

E5V

+5V

STM32 NUCLEO

USB

JP5

U4

3V3 LDO

J1

3V3

J2

VREF

U2

2.5 LDO

EXT ADC

UM2649

Solder bridges

All the analog supplies are generated starting from the 3V3 coming from the LDO on the STM32 Nucleo boards.

Starting from this source, two dif

• U1 LDO which outputs 3 volts used by the microphones connected to the external ADC and all the relevant components

• U2 LDO which generates 2.5 volts and feeds the single microphone connected to the internal STM32 ADC as well as the STM32 analog reference

Note: in the standard board configuration, the single microphone (M3OB) connected to the STM32 ADC is disabled by

Caution: Do not close J2 if the proper solder bridge is not open on the STM32 Nucleo board, as the STM32 Nucleo and

2.4 Solder bridges

default; to enable this feature two actions are required:

• unsolder a solder bridge on the STM32 Nucleo (the solder bridge depends on the STM32 Nucleo type, as detailed in Section 3.1.2 Single microphone acquisition configuration)

• close J2 header

the X-NUCLEO-AMICAM1 expansion board could be damaged (refer to Section 3.1 Board setup for further information).

The on-board USB connector supports audio streaming to the host PC and can also be used to power the whole system up, including the STM32 Nucleo board, by:

• closing jumper J1 on the X-NUCLEO-AMICAM1 expansion board

• placing JP5 in position E5 on the STM32 Nucleo development board

Solder bridges allow you to choose among different configurations and enable or disable on-board microphones versus microphone coupon boards.

ferent regulators are used on the X-NUCLEO-AMICAM1 expansion board:

UM2649 - Rev 1

page 5/17

Table 1. X-NUCLEO-AMICAM1: solder bridge functions

Function Solder bridge

I²S serial data 2 from external ADC SB1

I²S bit clock to external ADC SB2

I²S serial data 1 from external ADC SB3

I²S word select SB4

Amplified single microphones to STM32 ADC pin SB6

NRST signal to external ADC reset pin SB7

NRST signal to external ADC reset pin SB8

Microphone coupon M5 connected to STM32 ADC SB9

On-board microphone M3OB connected to STM32 ADC SB10

I²S master clock to external ADC SB11

SPI CS to external ADC SB12

SPI MOSI to external ADC SB13

SPI MISO from external ADC SB14

SPI clock SB15

I²S bit clock to external ADC SB16

I²S master clock to external ADC SB18

USB DP signal SB19

USB DM signal SB20

I²S serial data 2 from external ADC SB21

I²S bit clock to external ADC SB22

Microphone coupon M1 connected to external ADC SB23

On-board microphone M1OB connected to external ADC SB24

Microphone coupon M2 connected to external ADC SB25

On-board microphone M2OB connected to external ADC SB26

UM2649

Connectors

2.5 Connectors

Connector Pin Signal Remarks

CN7

UM2649 - Rev 1

Table 2. X-NUCLEO-AMICAM1 expansion board: ST morpho connectors

1 I2S_CK

2 I2S_SD2

3 I2S_SD1

4 NRST

6 E5V

8 GND

12 3V3

14 NRST

16 3V3

17 I2S_WS

page 6/17

Connector Pin Signal Remarks

18 5V

19 GND

CN7

CN10

20 GND

22 GND

28 M5+

1 SPI_CS

4 I2S_MCLK

7 A2V5 If J2 is closed

9 GND

11 GND

12 OTG_FS_DP_NUCLEO

13 SPI_MISO

14 OTG_FS_DM_NUCLEO

15 SPI1_MOSI

19 I2S_MCLK

20 GND

25 GND

26 GND

30 I2S_CK

32 AGND

UM2649

Connectors

Table 3. X-NUCLEO-AMICAM1 expansion board: Arduino connectors

Connector Pin Signal Remarks

2 3V3

3 NRST

4 3V3

CN6

CN8 1 M5+

CN5

CN9 7 I2S_CK

5 5V

6 GND

7 GND

8 V_IN

2 I2S_MCLK

4 SPI_MOSI

5 SPI_MISO

6 SPI_SCK

7 GND

8 A2V5 If J2 is closed

UM2649 - Rev 1

page 7/17

UM2649

System requirements

3 System requirements

To use the X-NUCLEO-AMICAM1 expansion board, you need the same hardware and software resources of

STM32 Nucleo boards (for details, refer to UM1724 on www

disk and at least 128 MB of RAM to run the firmware package.

3.1 Board setup

The X-NUCLEO-AMICAM1 expansion board can be connected to any STM32 Nucleo board. However, the related firmware offers an out-of-the-box package for some STM32 Nucleo boards.

When mounting the X-NUCLEO-AMICAM1 on the STM32 Nucleo, align all the pins with their corresponding connector.

Caution: 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.

The default X-NUCLEO-AMICAM1 configuration allows the acquisition of two on-board microphones (M1OB and M2OB) through the external ADC mounted on the board.

The following configurations and use cases can also be implemented:

• 4 microphone acquisition using coupon boards (e.g. STEVAL-MIC004V1) and the external ADC

• single microphone acquisition using STM32 embedded ADC

.st.com) as well as 40 MB of free space on your hard

3.1.1 4 microphone acquisition configuration

Step 1. Open SB24 and SB26 to disconnect M1OB and M2OB on-board microphones from the ADC

Step 2. Close SB23 and SB25 to connect M1 and M2 external headers to the ADC

Step 3. Mount coupon boards on the headers

Caution: Do not close SB23 and SB24 at the same time to avoid potential shortcircuit between M1OB on-board

microphone and M1 external microphone if the coupon is mounted.

Do not close SB25 and SB26 at the same time: it will result in a potential shortcut between M2OB onboard microphone and M2 external microphone if the coupon is mounted.

3.1.2 Single microphone acquisition configuration

Step 1. Change the solder bridge configuration on the STM32 Nucleo to allow VREF routing to the appropriate

STM32 pin as follows:

–

On STM32 Nucleo-XXXXRX 64-pin boards (MB1136): open SB57

– On STM32 Nucleo-LXXXZX 144-pin boards (MB1312): open SB149, close SB 119

– On STM32 Nucleo-XXXXZX 144-pin boards (MB1137): open SB12

Step 2. Close J2 on the X-NUCLEO-AMICAM1 board.

Caution: Do not close J2 if the proper solder bridge is not open on the STM32 Nucleo board, as the STM32 Nucleo and

the X-NUCLEO-AMICAM1 expansion board could be damaged.

Step 3. Check SB9 and SB10 on the X-NUCLEO-AMICAM1.

– SB10 closed, SB9 open: acquisition of the on-board M3OB microphone

– SB10 open, SB9 closed: acquisition of an external coupon plugged onto M5 header

Caution: Do not close SB9 and SB10 at the same time as a potential shortcircuit could occur between M3OB on-board

microphone and M5 external microphone if the coupon board is mounted.

UM2649 - Rev 1

page 8/17

4 Bill of materials

Table 4. X-NUCLEO-AMICAM1 bill of materials

Item Q.ty Ref. Part / Value Description Manufacturer Order code

1 1 CN5 HEADER 10 Arduino connector

2 2 CN6, CN9 HEADER 8 Arduino connectors

3 2 CN7, CN10 HEADER 19x2 Morpho connectors

4 1 CN8 HEADER 6 Arduino connector

C1, C2, C4, C5, C8, C1

1, C12, C13,

5 20

6 11

7 8

8 1 C20

9 1 C21

10 1 C23

11 1 C27

12 1 C36

13 1 D1 ESDA7P60-1U1M

14 1 D2 STPS160A Schottky diode ST STPS160A

15 2 J1, J2 HEADER 2 Stripline TH 2 pin Harwin M20-9773646

16 3

17 5

C19, C22, C25, C28, C33, C35, C37, C38, C39, C40, C43, C44

C3, C14, C15, C16, C17, C18, C24, C31, C34, C41, C42

C6, C7, C9, C10, C26, C29, C30, C32

M1OB, M2OB, M3OB

M1, M2, M3, M4, M5

1 µF X5R ±10% 0402 (1005 Metric)

100 nF 16 V X7R ±10% 0402 (1005 Metric)

10 nF 16 V X7R ±10% 0402 (1005 Metric)

39 nF 25 V X7R ±10% 0402 (1005 Metric)

47 µF 10 V X5R ±20% 0805 (2012 Metric)

2.2 nF 16 V X7R ±10% 0402 (1005 Metric)

10 µF 10 V X5R ±10% 0805 (2012 Metric)

10 nF 16 V X7R ±10% 0402 (1005 Metric)

MP23ABS1

HEADER 3X2

Ceramic capacitors Kemet C0402C105K8PAC7411

Ceramic capacitors Kemet C0402C104K4RAC7411

Ceramic capacitors (not mounted)

Ceramic capacitor Murata GRM155R71E393KA88D

Ceramic capacitor Taiyo Yuden LMK212BBJ476MG-T

Ceramic capacitor Wurth Elektronik 885000000000

Ceramic capacitor

Ceramic capacitor Yageo CC0402KRX7R7BB103

High junction temperature T

High performance MEMS audio sensor single ended analog bottom-port microphone

Analog microphone coupon connector

Samtec or equivalent

Yageo CC0402KRX7R7BB103

Samsung ElectroMechanicsMurata

ST ESDA7P60-1U1M

ransil

ST MP23ABS1TR

Fischer Elektronik or equivalent

SSQ-110-21-F-S

SSQ-108-21-F-S

SSQ-119-01-L-D

SSQ-106-21-F-S

CL21A106KPFNNNG

BL1/36Z

UM2649

Bill of materials

UM2649 - Rev 1

page 9/17

UM2649

Bill of materials

Item Q.ty Ref. Part / Value Description Manufacturer Order code

18 1 R1

19 1 R2

20 1 R3

21 1 R4

22 1 R5

23 8

24 9

25 1 R11

26 9

27 1 R17

28 1 R18

29 1 R19

30 4

31 2 R42, R43

32 14

33 10

34 1 SP1 Not mounted Any Any

35 1 USB1 USB Mini-B USB connector CUI UJ2-MBH-1-SMT-TR

R6, R7, R8, R9, R12, R13, R14, R15

R10, R25, R28, R29, R32, R33, R36, R38, R41

R16, R22, R23, R24, R30, R31, R34, R35, R37

R26, R27, R39, R40

SB1, SB2, SB3, SB4, SB6, SB10, SB12, SB13, SB14, SB15, SB19, SB20, SB24, SB26

SB7, SB8, SB9, SB1

1, SB16, SB18, SB21, SB22, SB23, SB25

1.5 K OHM ±1% 1/16 W 0402 (1005 Metric)

33 K OHM ±1% 1/16 W 0402 (1005 Metric)

12 K OHM ±1% 1/16 W 0402 (1005 Metric)

51 K OHM ±1% 1/16 W 0402 (1005 Metric)

24 K OHM ±1% 1/16 W 0402 (1005 Metric)

0 OHM ±1% 0.2 W 0402 (1005 Metric)

10 K OHM ±1% 1/16 W 0402 (1005 Metric)

3.32 K OHM ±1%

0.1 W 0402 (1005 Metric)

56 K OHM ±1%

0.12 W 0402 (1005 Metric)

160 OHM ±1% 1/16 W 0402 (1005 Metric)

4.7 K OHM ±1% 1/16 W 0402 (1005 Metric)

100 K OHM ±1%

0.12 W 0402 (1005 Metric)

2 K OHM ±1% 1/16 W 0402 (1005 Metric)

1 M OHM ±1% 1/16 W 0402 (1005 Metric)

0 OHM ±1% 0.1 W 0603 (1608 Metric)

SMD resistor (not mounted)

SMD resistor Vishay CRCW040233K0FKED

SMD resistor Vishay CRCW040212K0FKED

SMD resistor Vishay CRCW040251K0FKED

SMD resistor Vishay CRCW040224K0FKED

SMD resistors Vishay CRCW04020000Z0EDHP

SMD resistors Panasonic ERA2AEB103X

SMD resistor Panasonic ERJ-2RKF3321X

SMD resistors TE Connectivity CRGP0402F56K

SMD resistor TE Connectivity CPF0402B160RE1

SMD resistor ROHM MCR01MZPF4701

SMD resistor TE Connectivity CRGP0402F100K

SMD resistors Vishay CRCW04022K00FKED

SMD resistors Vishay CRCW04021M00FKED

SMD resistor Vishay CRCW06030000Z0EB

SMD resistors (not mounted)

Vishay CRCW04021K50FKED

Vishay CRCW06030000Z0EB

UM2649 - Rev 1

page 10/17

Item Q.ty Ref. Part / Value Description Manufacturer Order code

36 2 U1, U2 LDK130M-R

37 1 U3 USBLC6-2SC6

38 1 U4 AD1974

39 1 U5 TSV912

40 2 U6, U7 TSV914

300 mA low quiescent current very low noise LDO

ESD protection for USB 2.0 high speed

4-channel dif

ferential ADC

Wide-bandwidth (8MHz) rail to rail input/output 5 V CMOS Op-Amps, dual

Wide-bandwidth (8MHz) rail to rail input/output 5 V CMOS Op-Amps, quad

ST LDK130M-R

ST USBLC6-2SC6

Analog Devices AD1974YSTZ

ST TSV912

ST TSV914

UM2649

Bill of materials

UM2649 - Rev 1

page 11/17

17 19

10 12

2

6

28 30

33

SPI1_MISO

29

SB1

I2S_CK

NRST

NC

SB3

8

5

4

8

SB2

1

3

3V3

34

SPI1_CS

32

23

18

SB6

0R

NC

SPI_MISO

6

HEADER 19x2

27

3

1

0R

8

CN9

1

0R

CN5

SB7

SB8

E5V

SB22

SB13

I2S_CK

OTG_FS_DP_NUCLEO OTG_FS_DM_NUCLEO

10

SB18

6

11 13

37

2

M5+

35 37

3

5

15

2

36

9

20

8

SB20

I2S_CK

SPI_CS

24

SB15

35

26

12

17 19

1

4

0R

16 16

I2S_MCLK

7

SB12

23

38

SPI_MOSI

NC

SB16

5

7

14

SPI1_MOSI

15

SPI1_SCK

CN6

I2S_MCLK

CN10

3

14

SB14

6

SB11

1

2221

9

I2S_SD1

31

A2V5

7

CN7

18

HEADER 19x2

2

6

NC

25

2

8

J2

4

24

28 3029

26

I2S_SD2

NC

4

21

2

38

9

5VV_IN

10

5

1

31 33

3

7

34 36

11

56

13 5

25

20 22

SPI_SCK

I2S_WS

321

CN8

27

4

SB21

3

4

I2S_SD2

SB4

SB19

0R

NC

0R

NC

0R 0R 0R

UM2649 - Rev 1

5 Schematic diagrams

Figure 6. X-NUCLEO-AMICAM1 circuit schematic - connectors

page 12/17

Schematic diagrams

UM2649

5

OUT

NRST

C2

R60

1

AGND3

36

24K

C19

C1

ASDATA1

24

5

GND

48

C10

1

D1

1

AD1974

16

17

47µF

ADC2LN

SPI_CS

100nF

NC8

1

21

ABCLK

22

C16

1

C9

NC

2

10K

R2

R150

5

C18

VBUS

D3

4

10µF

AVDD

38

39

30

2

C12

USB Mini-B100nF

USB1

D+

3

IN

1

PD/RST

10

M4+

1µF

3V3

STPS160A

C15

4

7

NC2

45

ADC2RP

C28

I2S_WS

MCLKO/XO

C29

NC

J1

CM

C8

R5

37

AVDD4

M2+

33K

NC7

31

100nF

D2

LDK130M-R

3V3

2

GND

100nF

D-

2

V_USB

28

25

DGND2

SPI_MISO

AVDD

15

LDK130M-R

42

ADC1RN

COUT

AGND2

5

11

NC

1µF

USB

51K

R10

3.0 V Analog LDO

AVDD3

C32

NC

9

SH4

to ADC

ID

4

C24

COMM

R70

M1+

NC10

ASDATA2

20

EN

3

NC3

8

43

ADC2LP

44

R4

NC5

100nF

ALRCLK

CIN

23

C25

C14

M1-

2

D2

3

CLATCH

27

R80

C30

NC

ADC

M3-

possible

SH3

8

D1

1

A2V5

1

V_USB

I2S_CK

DVDD

AVDD

2.2nF

1µF

MCLKI/XI

3

I2S_SD1

DGND1

13

DVDD1

SP1

C27

C13 R140

1µF

AUXDATA2

C17

NC9

29

Vbus

OUT

5

M3+

FILTR

35

M4-

C6

NC

SH2

7

E5V

M2-

GND

2

100nF

R3

IN

1

AUXBCLK

18

9

NC4

12

C5

32

AGND5

33

DVDD

USBLC6-2SC6U3

AGND1

3k32

NC

ADC1LP

40

C23

R120

I2S_SD2

AVDD1

C20 39nF

C31

C22

14

CCLK

26

I2S_MCLK

100nF

6

SH1

AGND4

R11

NC

4

R1 NC

R90

12K

AUXLRCLK

19

C21

2.5 V Analog LDO

2

AVDD2

34

3V3

SPI_SCK

OTG_FS_DM_NUCLEO OTG_FS_DP_NUCLEO

3V3

41

ADC1RP

C4

Place as close as

C7

NC1

6

SPI_MOSI

C11

NC

4

ESDA7P60-1U1M

DVDD

1µF

EN

3

C3

C26

NC

R130

2

U4

AUXDATA1

NC6

ADC1LN

D4

6

46

ADC2RN

LF

47

100nF

U1

U2

GND

2

Power supply

1µF

1µF 1µF

1µF

1µF 1µF

1µF

UM2649 - Rev 1

Figure 7. X-NUCLEO-AMICAM1 circuit schematic - USB, power

, external ADC

Schematic diagrams

page 13/17

UM2649

M4

14

11

IN4+

12

AVDD

COMM

R32 10K

C42

M2H

COMM

56K

M4OUT

M3+

4

GND2

1

DOUT

R28 10K

3

GND2

7

3

GND2

1

VDD

M4+

M1

R36 10K

MP23ABS1

AVDD

R41 10K

M2OB

9

IN3-

OUT

2

4

M2+

M2

100nF

COMM

4

IN4-

13

IN1-

3

R39 2K

5

GND3

COMM

GND2

6

GND4

R27 2K

R37

56K

OUT28OUT3

OUT1

2

AVDD

6

GND4

M2+

M2OB

COMM

M4-

5

IN1+

5

VCC+

6

TSV914

C38

1µF

1

M1+

OUT4

M1H

R40 2K

DOUT

10

VCC-

VDD

1

R24

M1OB

R29 10K

SB23

AVDD

R31 56K

3

GND1

COMM

M1+

1µF

R26 2K

IN3-

IN3+

10

COMM

R25 10K

U7

1µF

3

GND1

M3+

M3-

1µF

IN3+

M3OUT

GND2

6

GND4

GND3

M2OB

OUT

2

M2-

2

GND1

56K

VCC-

HEADER 3X2

R35 56K

AVDD

1

56K

M2H

M1-

HEADER 3X2

4

GND2

3

M4OUT

VCC+

6

IN2-

SB25

5

IN2+

SB26

MP23ABS1

R33 10K

SB24

4

HEADER 3X2

R38 10K

R23

8

OUT3

C41

OUT1

2

IN1-

R22

6

GND4

M1H

M3OUT

GND3

U6

C39

100nF

M3

IN2+

4

3

IN1+

GND1

3

GND1

4

GND3

COMM

R30 56K

M1OBAVDD

COMM

M1OB

COMM

AVDD

M4+

2

VDD

1

Microphones

OpAmp

TSV914

M1OUT

GND3

M2OUT

2

OUT

AVDD

1

VDD

5

GND3

2

OUT

C40

M2OUTM1OUT

C44

HEADER 3X2

11

IN4+

12

COMM

9

IN4-

13

GND1

5

IN2-

7

OUT2

OUT4

14

C37

C43

5

VDD

R34 56K

1µF

NC

0R

0R 0R

UM2649 - Rev 1

Figure 8. X-NUCLEO-AMICAM1 circuit schematic - microphones to external ADC

page 14/17

Schematic diagrams

UM2649

IN2+

4

VCC-

C34

1µF

R43

M3OB

R42 1M

MINTOUT

VDD

1

VCC+

IN1-

3

M5H

10nF

A2V5

DOUT

4

8

3

GND2

INTREF

INTREF_BUFF

C33

MP23ABS1

GND2

6

GND4

C36

5

GND3

TSV912

R19 100k

C35

1

GND1

OUT

2

R16 56K

MINTOUT

INTREF

A2V5

IN1+

5

A2V5

1

OUT1

2

4

1M

M5+

6

IN2-

7

OUT2

HP Filter --> fc = 2.8Hz LP Filter --> fc = 99.4 KHz

R184.7k

SB9 NC

M3OB

M5H

INTREF_BUFF

A2V5

R17 160

M5

M3OB

5

VDD

HEADER 3X2

GND3

100nF

U5

INTREF_BUFF

3

GND1

SB10 0R

2

1µF

UM2649 - Rev 1

Figure 9. X-NUCLEO-AMICAM1 circuit schematic - microphones to internal ADC

page 15/17

Schematic diagrams

UM2649

Revision history

able 5. Document revision history

T

Date Version Changes

09-Dec-2019 1 Initial release.

UM2649

UM2649 - Rev 1

page 16/17

UM2649

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UM2649 - Rev 1

page 17/17