DM00061574

DM00061574

AN4146

Application note

STSmartVoice demonstration board STEVAL-MKI126Vx

MEMS Digital

Microphone 1

Introduction

This application note describes the STSmartVoice demonstration board STEVAL-

MKI126Vx. The connections and setup of the programming and interface boards are also detailed as well as other versions of the main board hosting the different microphones.

The STA321MP/MPL (package option respectively VFQFPN56 and TQFP64) has been designed to decode the pulse-density modulation (PDM) signal coming from the microphones and convert it into the most common digital audio format: I

2

S. The device is also able to provide pulse-width modulation (PWM) outputs, one per channel, suitable to support an analog interface. The processor also includes a digital block, the hardware accelerator, composed of a chain of biquads (see

Figure 1

).

The STEVAL-MKI126Vx board can connect up to six microphones using the sockets provided or through a dedicated six-microphone array. The digital interface of the device allows interfacing the MIC output to the most widely used audio receivers and digital amplifiers or simply evaluating the MIC using generic audio measurement equipment. The filtered PWM signals allow the connection of a headset to listen to the audio received through the microphones.

The fully digital path ensures a high level of processing with sound preconditioning, filtering and voice enhancement. The pre- and post-mixing of the signals coming from the microphones, in combination with the frequency equalization block, allow the implementation of acoustic algorithms such as beam forming.

Figure 1. Microphone processor

MEMS Digital

Microphone 6

SDA

SCL

STA321MP/MPL

PDM

Interface

I2C

1

6

Audio

Matrix

( Muxing/

Mixing )

PLL

Scalable

Microphone

Processor TM

Hardware

Accelerator

PWM

Serial Data

Output

I

2

S

OUTxA

OUTxB

LRCK

BICK

SDAT 1/2/3

Clock management

March 2013 DocID023502 Rev 2 1/30

www.st.com

Contents

Contents

AN4146

1

2

Demonstration board and accessories . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.1

Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2

STEVAL-MKI126Vx board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3

Microphone adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.4

STEVAL-MKI126Vx overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.5

STEVAL-MIKI126Vx connections and setup . . . . . . . . . . . . . . . . . . . . . . . 9

1.5.1

1.5.2

1.5.3

1.5.4

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Clock management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

MEMS microphones, PDM interface and level shifter . . . . . . . . . . . . . . 12

Output section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Selectors, jumpers and connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.1

Selectors and jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.2

Microphone audio adapter connections . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3 Software settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Appendix A STEVAL-MKI126Vx schematics, layout and BOM . . . . . . . . . . . . . . 22

4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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AN4146

List of tables

List of tables

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Table 6.

L/R channel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Selectors and jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Jumpers and further options - summary table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

I

2

C writes of setup file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

STEVAL-MK126Vx bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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List of figures

List of figures

AN4146

Figure 1.

Microphone processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2.

STEVAL-CCA035V1 (APWLink). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 3.

STEVAL-MKI138V1 (ST audio hub) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 4.

STEVAL-MKI126Vx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 5.

MP34DT01 microphone adapter board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 6.

STEVAL-MKI126Vx - block diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 7.

STEVAL-MKI126Vx placement and serigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 8.

Power supply - block diagram subsection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 9.

Clock management - block diagram subsection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 10.

Microphones and I/O interfaces - block diagram subsection . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 11.

Headphone out schematic - only one channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 12.

Female headers on STEVAL-MKI126Vx board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 13.

Microphone audio adapter board plugged into STEVAL-MKI126

(STSmartVoice demonstration board) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 14.

Interface board connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 15.

APWorkbench launch wizard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 16.

APWorkbench tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 17.

Multi-microphone interface panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 18.

Pre- and post-mixer of channel 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 19.

STEVAL-MKI126Vx schematic - page 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 20.

STEVAL-MKI126Vx schematic - page 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 21.

STEVAL-MKI126Vx schematic - page 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 22.

STEVAL-MKI126Vx schematic - page 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 23.

STEVAL-MKI126Vx layout - top view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 24.

STEVAL-MKI126Vx layout - bottom view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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AN4146

1

Demonstration board and accessories

Demonstration board and accessories

The STSmartVoice board STEVAL-MKI126Vx requires a dedicated interface board,

STEVAL-CCA035V1 (APWLink) or STEVAL-MKI138V1 (ST audio hub), for programming the device. Additional boards hosting the microphones are compatible with the board using suitable connectors placed onboard. These boards are listed and shown in the following sections and figures.

1.1 Interface

I

The STEVAL-CCA035V1 works as a programming board since it manages writing to the

2

C. The microphone processor is a digital device set using the I

2

C commands. In addition, the STEVAL-CCA035V1 also serves as an interface board since the I

2

S provided by the processor is routed on its connector (referred to as the APWLink connector). Finally, this board also provides on the connector the 12.288 MHz clock used by the processor in case the sampling frequency of the I

2

S is 192 kHz or 48 kHz.

Figure 2. STEVAL-CCA035V1 (APWLink)

The STEVAL-MKI138V1 performs the functions listed above plus supports audio streaming via the USB cable. Basically the ST audio hub, using the STM32F107RC microcontroller, is able to program the STA321MPL device via the I

2

C and decodes the I

2

S into a USB stream in order for the PC to manage the sound captured by the microphones.

Figure 3. STEVAL-MKI138V1 (ST audio hub)

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Demonstration board and accessories AN4146

The main task of the STEVAL-MKI126Vx in

Figure 4

is to convert the PDM signals provided

by the microphones both into the more common I

2

S and PWM. The I

2

S signal is routed both on a general connector and APWLink connector. The PWM signals, properly filtered, provide an analog interface. There are two different versions of the board depending on the microphones soldered onboard:

STEVAL-MKI126V1: MP45DT02 devices have been soldered

STEVAL-MKI126V3: MP34DT01 devices have been soldered

Figure 4. STEVAL-MKI126Vx

6/30

Microphone adapters are small circular PCBs with a single soldered MEMS microphone.

There are three different ordering codes for each board corresponding to the different type of mounted digital microphone (STEVAL-MKI129V1 for the MP34DT02, STEVAL-MKI129V2 for the MP34DB01, and STEVAL-MKI129V3 for the MP34DT01. Please refer to AN4184

“Microphone coupon boards STEVAL-MKI129Vx based on the MP45DT02, MP34DB01, and MP34DT01” for further details.

Figure 5. MP34DT01 microphone adapter board

DocID023502 Rev 2

AN4146 Demonstration board and accessories

Figure 6. STEVAL-MKI126Vx - block diagram

Array connector

STEVAL-MKI126V

3.3V

Vdd

Clk

L/R gnd

MIC3 MIC4 MIC5 MIC6

Vdd Vdd Vdd

Out Clk

L/R gnd

Out Clk

L/R gnd

Out Clk

L/R gnd

Out

S6 S7

J3

S8 S9

J4

S3

Vdd

Clk

L/R

Out gnd

MIC1

S5

SW1

SW2

Vdd

Clk

L/R gnd

Out

MIC2

S4

3.3V

S2 JP1

Regulator

1.8V

Regulator

3.3V

3.3V

S12 S13 S14 S15 S16 S17

3.3V

Level shifter

High

3.3V

Low

1.8V

3.3V

Flip-flop

/2

/4

PDM Interface

CK

STA321MPL

I2C

PWM

I2S

(3x)

OpAmp

LRCK

BICK

SDO12

SDO34

SDO56

S1

S10 S11

HP Jack

I

2

S connector

+3.3V

Gnd +5V

11.2896MHz

APWlink connector

The board hosts the homonymous microphone processor STA321MP or MPL according to the package.

It also includes two voltage regulators in order to provide the required voltages. One regulator generates 3.3 V for supplying both the processor and the microphone and the other one generates 1.8 V in case the user desires to supply the microphones at this voltage.

For the reason above, there is also a voltage level shifter that must be used if the microphones and the processor are fed with different voltages.

Another important section is represented by the clock. The board hosts an oscillator in order to provide the clock to the processor. The device is able to generate the clock for the microphones (default clock-out value / 4), but a flip-flop has been introduced for dividing the STA321MP clock out for a debugging purposes; the flip-flop during normal use is bypassed.

The input section is represented by the two soldered microphones, the four microphone

sockets and the 8x2 header connector for the microphone array. The board has been

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Demonstration board and accessories AN4146

designed for automatically switching from the microphones onboard to the microphones on the array thanks to two voltage-controlled switches SW1 and SW2.

The output section is represented by an I

2

S connector that exports the I

2

S bus and a headphone amplifier, TS482, which also allows a digital-to-analog path. These two paths allow interfacing the microphones to, respectively, a generic audio processor or measurement equipment or to interface the MEMS to a PC.

I

A further component is the APWLink connector that allows the control of the processor via

2

C. This connector also provides a 3.3 V source line and I

2

S signals.

All selectors have their own name on the board serigraphy and are composed of two resistors where only one is soldered according to the desired functionality.

Figure 6

depicts all the components listed and the different colored traces represent the

following sections of the board:

Power supply (green trace)

Clock management (black trace)

PDM interface (rainbow traces)

Output sections

– Headphone out (fuchsia trace)

– I

2

S signals (fuchsia trace)

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AN4146

1.5

Demonstration board and accessories

STEVAL-MIKI126Vx connections and setup

The figure below represents the placement of the component and the selectors, made up of resistors, which manage all the possible configurations and signals paths supported by the demonstration board.

Figure 7. STEVAL-MKI126Vx placement and serigraphy

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Demonstration board and accessories AN4146

S3

The STA321MP processor needs 3.3 V as a supply voltage while the operative voltage range of the microphones is 1.64 V - 3.6 V where the typical value is 1.8 V. For this reason there are two voltage regulators onboard. One regulator is used to generate the 3.3 V from an external 5 V supply (J20) while the other one generates the 1.8 V from the 3.3 V. The

3.3 V can also be provided from the APWLink connector on pin 11 and enabled on the board by closing JP1. In spite of the fact that the STEVAL-CCA035V1 board is always connected

(for the I

2

C communication) and so 3.3 V is always provided to the STEVAL-MKI126Vx, the demonstration board also hosts the 3.3 V regulator (scaled by an external 5 V supply) to allow better noise immunity. The following diagram depicts the supply lines scheme: S2

(R78-R79) selects the 3.3 V source while S3 (R80-R81) selects either 1.8 V or 3.3 V as the microphone supply voltage. These selectors are indicated on the board with the serigraphy

3V3 SEL and MIC_VCC, respectively.

Figure 8. Power supply - block diagram subsection

S2 JP1

APWlink connector

Regulator

1.8V

Regulator

3.3V

+3.3V

Gnd +5V

Once the 3.3 V voltage supply has been chosen, the devices that are fed with this voltage are the STA321MP, the flip-flop, the level shifter and the opamp. Regarding the microphones section, the selector S3 offers the possibility to choose their supply level.

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AN4146 Demonstration board and accessories

Clock management is an important topic since all of the devices involved have their own clock.

Figure 9. Clock management - block diagram subsection

Microphones

Clock

S10 S11

3.3V

Level shifter

High

3.3V

Low

1.8V

3.3V

3.3V

Flip-flop

/2

/4

PDM Interface

CK

STA321MPL

S1

APWlink connector

11.2896MHz

The processor device needs two clocks: one for its digital core and one for the PDM (a register bit allows selecting the ratio between the two clocks). The microphones and the

PDM interface need the same clock while the processor core clock is fed with a quadruple of such clock. The core clock can be provided to the processor through the STEVAL-

CCA035V1, 12.288 MHz on pin 15, or thanks to an onboard 11.2896 MHz oscillator, the selector S1 (R82-R83) is used to select one of these two clocks. The choice of the frequency value depends on the desired output sampling frequency of the I

2

S:

12.288 MHz: Fs = 12.288/64 = 192 kHz

→ Fs = 48 kHz enabling I

2

S decimator

11.2896 MHz: Fs = 11.2896/64 = 176.4 kHz

→ Fs =44.1 kHz enabling I

2

S decimator

The clock for the microphones and PDM interface is generated thanks to the PLL enabling the device microphone mode (refer to the STA321MP datasheet) and exported thanks to the clock-out (pin 25). The PDM interface is internally clocked by enabling one bit of a dedicated device register. If the microphone mode is not enabled, the external flip-flop is used as a frequency divider of the clock-out; this is for a debugging purposes only. For this reason, the

I/F_CLK pin stays open by not soldering it to R32.The clock routing is managed by the two selectors S10, S11 called MIC_CLK_SEL on the board serigraphy. In microphone mode, the

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Demonstration board and accessories AN4146

clock-out works exactly as the microphone clock, so it must be provided to the microphone pins. This is done by closing the resistor R43 of the selector S11 (R42-R43). In the case of supplying the microphones at 1.8 V, the clock provided to the microphones must be reduced from 3.3 V to 1.8 V. The level shifter provides this scaled clock, if needed. When the user wants to feed the microphones at 1.8 V, the resistor R42 of the selector S11 must be soldered instead of R43 (R42-R43).The selector S10 (R40-R41) is used when the microphone mode is not enabled, thus, for debugging purposes only. For this reason, both of its resistors are not soldered.

L/R

GND

VDD

Table 1. L/R channel selection

Clock low

Data valid

High impedance

Clock high

High impedance

Data valid

Since the STA321MP processor manages the channels separately, there is no need to set the microphone in stereo configuration in this demonstration board. The L/R pins can be set to either GND or VDD through the selectors S4, S5, S6, S7, S8 and S9 (respectively the couples R38-R39, R36-R37, R46-R47, R44-R45, R48-R49 and R50-R51). By default, all the L/R pins are connected to GND, in other words R36, R38, R44, R46, R48 and R51 are soldered.

The processor STA321MP samples the microphone data according to the PDM interface clock. The sampling edge can be set to both rising and falling since, in microphone mode, the processor provides an internal PDM interface clock shifted 90º with respect to the clockout. Refer to the STA321MP/MPL datasheet for details.

The data output is a digital signal carrying the audio information with a PDM encoding. The processor STA321MP is able to decode these signals and convert them into the more common I

2

S and PWM. The I

2

S signal is routed both on a general connector and APWLink connector; the PWM signals, suitably filtered, provide an analog interface (fuchsia traces in

Figure 10 on page 13

).

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AN4146 Demonstration board and accessories

Figure 10. Microphones and I/O interfaces - block diagram subsection

Array connector

3.3V

Vdd

Clk

L/R gnd

MIC3 MIC4 MIC5 MIC6

Vdd Vdd Vdd

Out Clk

L/R gnd

Out Clk

L/R gnd

Out Clk

L/R gnd

Out

S6 S7

J3

S8 S9

J4

3.3V

3.3V

Vdd

Clk

L/R

Out gnd

MIC1

S5

SW1

SW2

Vdd

Clk

L/R

Out gnd

MIC2

S4

3.3V

S12 S13 S14 S15 S16 S17

3.3V

Level shifter

High

3.3V

Low

1.8V

PDM Interface

STA321MPL

PWM

I2S

(3x)

OpAmp

LRCK

BICK

SDO12

SDO34

SDO56

HP Jack

I

2

S connector

APWlink connector

The inputs of the PDM interface depend on the group of selectors S12, S13, S14, S15, S16 and S17 called Data Level SEL (respectively the couples R64-R65, R70-R71, R66-R67,

R72-R73, R68-R69 and R74-R75). These selectors are set if the PDM inputs come from the microphones or from the level shifter.

The level shifter (enabled through the level shifter EN) is used when the microphones supply voltage is set to 1.8 V. Under this condition the sensors are a 1.8 V section while the decoder is still a 3.3 V section. In order to match these two board portions, a level shifter is needed to increase the PDM data output level before providing it to the processor.

In a default configuration the PDM inputs are directly connected to the microphones data, in other words R65, R67, R69, R71, R73 and R75 are soldered.

Microphones 1 and 2 are always connected since they are soldered on the board

(a)

, the other four inputs depend on the connection of the microphone adapter boards. If the user wants to use the external microphone array, the microphone adapter boards must be unplugged and then the user must connect the array to the array connector with the dedicated cable. When the array is plugged in, pin 2 of the array connector is forced to a. Regarding MIC1 and MIC2, the board can host every type of ST digital microphone since it supports all the footprints

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Demonstration board and accessories AN4146

ground (due to the array board schematic) and this trace is used to switch off the LED D1 and to control the voltage-controlled switches SW1 and SW2 (IC1 and IC2 on the STEVAL-

MKI126Vx board). The LED switching off indicates that the array is connected and the switches commutate the PDM input 1 and 2 from the data of the microphones onboard to the data of the microphones on the array.

The output section is simply represented by a connector that exports the I

2

S bus (J17) and an operational amplifier used as the headphone driver. The STA321MP includes a PWM modulator so it possible to export this signal and after a suitable filtering (refer to

Figure 11

)

an analog signal is obtained. This dual output option allows interfacing the microphones to both a digital processor (through the I

2

S interface) and to analog systems like the PC line in

(filtered output).

Figure 11. Headphone out schematic - only one channel

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AN4146

2

Selectors, jumpers and connectors

Selectors, jumpers and connectors

2.1 Selectors and jumpers

Name on block diagram

S1

S2

S3

S4

S5

S6

S7

S8

S9

S10

S11

DEBUGGING

PURPOSES ONLY

S12

Table 2. Selectors and jumpers

Serigraphy

MCK_Sel

3V3 SEL

MIC_VCC

LR_H/L

LR_H/L

MIC CLK SEL

MIC CLK SEL

Data Level SEL

Function

Core clock selection:

R82: Coming from APWLink connector

R83: Coming from on-board oscillator

3.3 V selection:

R78: External supply needed

R79: Coming from APWLink connector

Microphone supply voltage:

R80: 3.3 V

R81: 1.8 V

Microphone 2 L/R:

R38: GND

R39: Vdd

Microphone 1 L/R:

R36: GND

R37: Vdd

Microphone 3 L/R:

R46: GND

R47: Vdd

Microphone 4 L/R:

R44: GND

R45: Vdd

Microphone 5 L/R:

R48: GND

R49: Vdd

Microphone 6 L/R:

R50: Vdd

R51: GND

Microphone clock voltage level:

R42: 1.8 V

R43: 3.3 V

Microphone clock voltage level:

R40: 1.8 V

R41: 3.3 V

PDM1 selection:

R64: when microphones are 1.8 V supplied

R65: when microphones are 3.3 V supplied

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Selectors, jumpers and connectors AN4146

Table 2. Selectors and jumpers (continued)

Name on block diagram Serigraphy Function

S13

S14

S15

S16

S17

Data Level SEL

Data Level SEL

Data Level SEL

Data Level SEL

Data Level SEL

PDM2 selection:

R70: when microphones are 1.8 V supplied

R71: when microphones are 3.3 V supplied

PDM3 selection:

R66: when microphones are 3.3 V supplied

R67: when microphones are 3.3 V supplied

PDM4 selection:

R72: when microphones are 1.8 V supplied

R73: when microphones are 3.3 V supplied

PDM5 selection:

R68: when microphones are 1.8 V supplied

R69: when microphones are 3.3 V supplied

PDM6 selection:

R74: when microphones are 1.8 V supplied

R75: when microphones are 3.3 V supplied

JP1

Table 3. Jumpers and further options - summary table

Name on block diagram

Serigraphy Function

J3-J4

3V3 APW

TWIN3-TWIN2

Level shifter EN

PLL_Bypass

3V3 from APWLink board enable:

Closed: 3V3 from APWLink

Open: line open

Reserved

Level shifter enable:

Pin 1: GND device is disabled

Pin 3: 1.8 V device is enabled

PLL bypass or not:

R76: PLL is bypassed

R77: PLL not bypassed

16/30 DocID023502 Rev 2

AN4146 Selectors, jumpers and connectors

Connecting the microphone audio adapter boards is very simple. The STEVAL-MKI126Vx board hosts four groups of three female headers like those depicted in the figure below. The

J12, J25 and J26 group can host one of the three different types of microphone audio adapters

Figure 12. Female headers on STEVAL-MKI126Vx board

Figure 13

shows the connection of the audio adapter board for the MP34DT01. It’s also possible to cut one of the microphones and use a single small circular PCB, allowing the evaluation of a different type of digital microphone at the same time.

Figure 13. Microphone audio adapter board plugged into STEVAL-MKI126

(STSmartVoice demonstration board)

DocID023502 Rev 2 17/30

Software settings AN4146

The demonstration board is programmed using the PC interface board STEVAL-CCA035V1

(APWLink) or STEVAL-MKI138Vx (ST audio hub). The figure below shows the connection using the APWLink connector (J15).

Figure 14. Interface board connection

To program the microphone processor STA321MP/MPL, the APWorkbench tool is needed.

Follow these steps to correctly set up the device:

1.

Run the tool

2. Click on the "MEMS Microphones Demo Kit" button

3. Select “STSmartVoice Demo Kit” in the “Microphone Kit Selection” box

4. Click on the "Run selected application…" button

Figure 15. APWorkbench launch wizard

18/30 DocID023502 Rev 2

AN4146 Software settings

The selection of the application allows the user to access all supported configurations of the

STSmartVoice board. The kit will work as a microphone onboard manager by selecting the

"Multi-microphone interface" choice. Then the user must confirm by clicking on the "Apply selected configuration" button.

Figure 16. APWorkbench tool

DocID023502 Rev 2 19/30

Software settings AN4146

The selection of the kit as a "Multi-microphone interface" will perform the I

2

C writes given in the table below.

Address

00

02

0A

0B

0C

0E

0F

04

07

08

5D

81

Value

9B

20

00

54

54

48

48

18

7A

80

01

09

Table 4. I

2

C writes of setup file

Note

PDM interface enable

20: FS = XTI/256.

Example:

44.1 kHz = 11.2896 MHz/256

48 kHz = 12.288 MHz/256

Ch4/5 Binary

Remove Soft Volume

Bridge power-UP

Master volume 0 dB

Ch1: +6 dB

Ch2: +6 dB

Ch4: +12 dB

Ch5: +12 dB

Microphone mode

Output I

2

S interface pins set as output

20/30 DocID023502 Rev 2

AN4146 Software settings

The selection of the kit as a "Multi-microphone interface" also lets the user access the dedicated panel given in the figure below.

Figure 17. Multi-microphone interface panel

The user can route the signal of the desired microphone on the output interfaces (I

2

S or HP out) using the mapping drop-down menus on the right side of the panel. These menus act on the pre-mixer of the respective channel. In the default configuration of the I

2

S output data

1 and 2 (SDO12), the pre-mixer of channel 1 takes 100% of PDMIN_1 (MIC1) and channel

2 takes 100% of PDMIN_2 (MIC2). The user can also directly edit the mixer values at will.

The post-mixer works in the same way, but takes a percentage of the outcome of the processing block.

As an example, the figure below shows the layout of the pre- and post-mixer of channel1.

Figure 18. Pre- and post-mixer of channel 1

DocID023502 Rev 2 21/30

Appendix A STEVAL-MKI126Vx schematics, layout and BOM

Figure 19. STEVAL-MKI126Vx schematic - page 1

R79

0R0

R78

0R0 N.F.

LRCKO

BICKO

SDO_12

SDO_34

SDO_56

I/F_CLK

CKOUT/4_H

9

7

5

3

1

3V3

3V3_INT

3V3_EXT

R81

0R0 N.F.

R80

0R0

J17

6

4

2

10

8

5X2_HEADER

R32

0R0 N.F.

1

2

1V8

MIC_VCC

PWDN

3V3_INT

3V3_INT

R7

10K

1

2

C9

1nF

C17

100nF

3V3_INT

3V3_INT

I/F_CLK

C15

100nF

C1

100nF

3V3_INT

PDMIN_6

PDMIN_5

PDMIN_4

PDMIN_3

PDMIN_2

PDMIN_1

RESET

3V3_INT

1

2

MVO

3

GND

VDD3.3

4

GND

5

VDD2.5

SDI78

6

SDI56

7

SDI34

8

9

SDI12

10

LRCKI

11

BICKI

VDD3.3

12

GND

13

VDD2.5

14

15

RESET

PLLB

16

U1

SDA

SCL

XTI

R3

3.3K

1

2

C13

1nF

C14

100pF

3V3_INT

C5

100nF

C8

100nF

3V3_INT

SDO_56

SDO_34

SDO_12

LRCKO

BICKO

48

OUT2A

OUT2B

VDD2.5

47

46

GND

45

44

VDD3.3

OUT3A

43

OUT3B

42

OUT4A

41

OUT4B

40

OUT5A

39

OUT5B

38

VDD2.5

37

GND

36

VDD3.3

OUT6A

OUT6B

35

34

33

C16

100nF

3V3_INT

EAPD

R29

10k

C12

100nF

C11

100nF

3V3_INT

R14

3.9K

R15

3.9K

R16

3.9K

C43

470pF R17

3.9K

C49

220pF

R31

5k

R18

3.9K

C44

150pF R19

3.9K

3.9K

R21

3.9K

R20

470pF

C45

3.9K

R23

3.9K

R22

150pF

C46

3.9K

R25

3.9K

R24

3V3_INT

R27

10k

C51

220pF

3V3_INT

R28

10k

3V3_INT

1

OUT1

2

IN1-

3

IN1+

4

GND

HPOUT1

U10

8

VCC

IN2+

7

OUT2

IN2-

6

5

TS482

R30

5k

C47

220pF

R26

10k

HPOUT2

C48

220pF

CKOUT_H

3V3_INT

XT_ACTIVE

CSX750FBC11.2896MTR

4 3

2

2 1

2

10K

Y1

R2

1

R1

100

1

OSC_CK

EN

R83

0R0

R82

0R0 N.F.

OSC_CK

XTI

MCLK

R85

0R0

R84

0R0 N.F.

3V3_INT

EN

HPOUT1

HPOUT2

C50

220uF

C52

220uF

2

3

1

HEADPHONE O/P

J24

AN4146 STEVAL-MKI126Vx schematics, layout and BOM

Figure 20. STEVAL-MKI126Vx schematic - page 2

J20

CN-02P

1

2

+

U7

IC-LD1117V33

3

VIN

GND

VOUT

2

C26

100nF

3V3_EXT

C27

100nF C18

100nF

1V8 3V3_INT

3V3_INT

C40

10uF

+

1V8

U2

1

VIN

LDS3985XX

OUT

3

VINH

5

C39

100nF

C2

33nF

C3

1uF

+

C24

10uF

MIC_DATA1

PDMIN_2_2378

MIC_DATA3

PDMIN_4_2378

MIC_DATA5

PDMIN_6_2378

CKOUT_L

CKOUT/4_H

C19

100nF

U6

1

VL

2

I/O_VL1

3

I/O_VCC2

4

I/O_VL3

5

I/O_VCC4

6

I/O_VL5

7

I/O_VCC6

8

I/O_VL7

9

I/O_VCC8

10

GND

VCC

20

I/O_VCC1

I/O_VCC3

19

I/O_VL2

18

17

I/O_VL4

16

I/O_VCC5

15

I/O_VL6

14

I/O_VCC7

13

I/O_VL8

12

OE

11

ST23783E

1

S1

3

2

PDMIN_1_2378

MIC_DATA2

PDMIN_3_2378

MIC_DATA4

PDMIN_5_2378

MIC_DATA6

CKOUT_H

CKOUT/4_L

1V8

CKOUT_H

CKOUT/2_H

3V3_INT

U4

1

2

CLR

1D

3

1CK

4

1PR

5

1Q

6

1Q

7

GND

CK

Q

CK

Q

D

Q

D

Q

74VHC74

VDD 14

2CLR 13

2D 12

2CK 11

2PR 10

2Q 9

2Q 8

CKOUT/4_H

C23

100nF

+

JP1

JP

3V3

SCL

MUTE

SDO_12

SDO_56

BICKO

2

R5 100

1

MCLK

2

0R0 R6

1

C4

47pF

5

7

9

1

3

11

13

15

C6

10pF

J15

2

4

6

8

10

12

14

16

SDO_34

LRCKO

2

R4 100

1

RESET

PWDN

SDA

FAIL

C7

10pF

DocID023502 Rev 2 23/30

STEVAL-MKI126Vx schematics, layout and BOM

Figure 21. STEVAL-MKI126Vx schematic - page 3

On Board MIC

R37

0R0 N.F.

R36

0R0

1

U3

GND

2

LR

VDD

DOUT

6

5

MIC_VCC

C10

10uF

C20

100nF

3

GND CLK

MP45DT01

4

C29

15pF

3

4

MP34DB01

U9

VDD L/R

DATA CLK

2

1

R8

100R

C28

15pF

MIC_DATA1_BOARD

MIC_CK

R39

0R0 N.F.

R38

0R0

1

U5

GND VDD

6

2

LR DOUT

5

3

GND CLK

4

C30

15pF

MP45DT01

3

4

MP34DB01

U11

VDD L/R

DATA CLK

2

1

MIC_VCC

C21

10uF

C22

100nF

R9

100R

C31

15pF

MIC_DATA2_BOARD

MIC_CK

AN4146

3

CLK

4

DATA

U12

L/R

2

VDD

1

MP34DT01

3

CLK

4

DATA

U13

L/R

2

VDD

1

MP34DT01

On board Mic socket

MIC_DATA3

R10

MIC_CK

JP

JP3

100R

C32

15pF

J26

1

2

1

J12

2

3

CON3

C33

15pF

CON3

3

J25

1

2

CON3

3

MIC_VCC

0R0 N.F.

R47

MIC_DATA5

C36

15pF

R12

MIC_CK

100R

J32

1

C37

15pF

J14

1

2

3

CON3

CON3

2

3

J31

CON3

1

2

3

MIC_VCC

0R0 N.F.

R49

MIC_DATA4

R11

MIC_CK

100R

C34

15pF

J30

1

2

3

1

2

J28

3

C35

CON3

15pF

CON3

J29

1

CON3

2

3

MIC_VCC

R45

0R0 N.F.

MIC_DATA6

C38

15pF

R13

MIC_CK

100R

J36

1

C41

15pF

1

J34

2

3

CON3

CON3

2

3

J35

1

2

CON3

3

MIC_VCC

0R0 N.F.

R50

24/30 DocID023502 Rev 2

AN4146 STEVAL-MKI126Vx schematics, layout and BOM

Figure 22. STEVAL-MKI126Vx schematic - page 4

Mic Array / on board Mic switch

MIC_DATA1_BOARD

MIC_DATA1

MIC_DATA1_ARRAY

MIC_DATA2_BOARD

MIC_DATA2

MIC_DATA2_ARRAY

75R

R54

6 S2

5

D

4 S1

IC1

IN 1

VCC

2

GND

3

ARRAY_DET

3V3_INT

C54

100nF

6 S2

5

D

4 S1

IC-STG719

IC2

IN 1

VCC

2

GND

3

IC-STG719

J3-1

J3-2

C55

100nF

MIC_DATA3

MIC_DATA4

J4-1

J4-2

MIC_DATA5

MIC_DATA6

MIC Input Selection Indicator

ARRAY_DET

3V3_INT

Mic data level selection

Default setting : 3V3

MIC_DATA1

PDMIN_1

PDMIN_1_2378

R65

0R0

R64

0R0 N.F.

MIC_DATA3

PDMIN_3

PDMIN_3_2378

MIC_DATA5

PDMIN_5

PDMIN_5_2378

MIC_DATA2

PDMIN_2

PDMIN_2_2378

MIC_DATA4

PDMIN_4

PDMIN_4_2378

MIC_DATA6

PDMIN_6

PDMIN_6_2378

R73

0R0

R72

0R0 N.F.

R75

0R0

R74

0R0 N.F.

R67

0R0

R66

0R0 N.F.

R69

0R0

R68

0R0 N.F.

R71

0R0

R70

0R0 N.F.

MIC CLOCK SELECTION

R40

CKOUT/4_L

0R0 N.F.

MIC_CK

R41

0R0

CKOUT/4_H

R42

0R0 N.F.

R43

0R0 N.F.

CKOUT_L

MIC_CK

CKOUT_H

MIC ARRAY INTERFACE

MIC_VCC

ARRAY_DET

MIC_CK

MIC_DATA1_ARRAY

MIC_DATA2_ARRAY

MIC_DATA3

MIC_DATA4

MIC_DATA5

MIC_DATA6

9

11

13

15

5

7

1

3

10

12

14

16

6

8

2

4

J38

LED On: On board Mic

LED Off: Mic Array

DocID023502 Rev 2 25/30

STEVAL-MKI126Vx schematics, layout and BOM

Figure 23. STEVAL-MKI126Vx layout - top view

AN4146

Figure 24. STEVAL-MKI126Vx layout - bottom view

26/30 DocID023502 Rev 2

AN4146 STEVAL-MKI126Vx schematics, layout and BOM

CCAP

CCAP

CCAP

CCAP

CCAP

CCAP

CCAP

CCAP

CCAP

CCAP

TCAP

Type

CCAP

CCAP

CCAP

RES

RES

RES

RES

RES

RES

RES

Package

Table 5. STEVAL-MK126Vx bill of material

Description Qty Reference

CC0603

CC0805

CC0603

CC0603 220 pF +/-10% NPO 50 V

CC1206

CC0603

10 uF +/-10% X7R 10 V

1 nF +/-5% X7R 50 V

CC0603

CC0603

CC0603

100 nF +/-10% X7R 50 V

10 uF +/-10% X7R 10 V

18

C1 C5 C8 C11 C12

C15 C16 C17 C18

C19 C20 C22 C26

C27 C54 C55 C23

C39

2 C10 C21

15 pF +/-10% NPO 50 V 12

C28 C29 C30 C31

C32 C33 C34 C35

C36 C37 C38 C41

4 C47-49 C51

1 uF +/-10% X7R 10 V

100 pF +/-10% NPO 50 V

10 pF +/-10% NPO 50 V

4 C24 C25 C40 C42

2 C9 C13

2 C3 C53

1 C14

2 C6 C7

CC0603 47 pF +/-10% NPO 50 V

CC0603 470 pF +/-10% NPO 50 V

CC0603 150 pF +/-10% NPO 50 V

CC0603

C7343

33nF +/-5% X7R 50V

220 uf 10 V +/-10% 125°C tanatalum

1 C4

2 C43 C45

2 C44 C46

1 C2

R0603

R0603

R0603

R0603

R0603

R0603

0 ohm +/-10% 1/8W

0 ohm +/-10% 1/8W

100 ohm +/-10% 1/8W

220 ohm +/-10% 1/8W

75 ohm +/-10% 1/8W

10K ohm +/-10% 1/8W

19

R6 R36 R38 R43

R44 R46 R48 R51

R65 R67 R69 R71

R73 R75 R76 R79

R80 R82 R84

20

R32 R37 R39 R40

R41 R42 R45 R47

R49 R50 R64 R66

R68 R70 R72 R74

R77 R78 R81 R83

R85

10

R1 R4 R5 R8 R9 R10

R11 R12 R13 R33

1 R34

1 R54

6

R2 R7 R26 R27 R28

R29

R0603 3.3 k ohm +/-10% 1/8W 1 R3

Manufacturer Remark

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Murata

AVX

Murata

Murata

Murata

Murata

Murata

Murata

Murata

Do not solder

DocID023502 Rev 2 27/30

STEVAL-MKI126Vx schematics, layout and BOM AN4146

Type Package

Table 5. STEVAL-MK126Vx bill of material (continued)

Description Qty Reference

RES

RES

Diode

OSC

Connector

Connector

Connector

Connector

Connector

Phonejack

Plastic supportor

Plastic supportor

IC

R0603 3.9 k ohm +/-1% 1/8W 12

R14 R15 R16 R17

R18 R19 R20 R21

R22 R23 R24 R25

2 R30 R31 R0603

D1206 SMD LED diode, red,1.8 V 1 D1

SMD5X7 CSX750FBC11.2896MTR

1 Y1

Throughhole

5K ohm +/-1% 1/8W

1x3 2.54 mm pitch female connector

12

J12 J14 J25 J26 J28

J29 J30 J31 J32 J34

J35 J36

Through- hole

Through- hole

Through- hole

1x3 2.54 mm pitch male connector

2x8 2.54 mm pitch male

Connector

2x5 2.54 mm pitch male connector

1

2

1

S1

J15 J38

J17

1x2 2.54 mm pitch male connector

5 J3 J4 JP1 JP3 J20

Through- hole

Through- hole

Through- hole

Through- hole

TQFP64

SONGCHEN CKX-3.5-06 female 8 mm male 3 mm

STA321MPL

1

4

4

J24

1 U1

Manufacturer

Murata

Murata any source

Citizen any source any source any source any source any source

Song Cheng any source any source

STMicroelectronics

Remark

IC VQFN56 STA321MP 1 U8 STMicroelectronics

Do not solder

IC

IC

IC

IC

IC

IC

SOT23-5

TSOP20

MINISO8

SO14

SOT223

SOT23-

6L

LDS3985M18R 1.8 V regulator

ST2378ETTR

TS482IST

1 U2

1 U6

1 U10

74VHC74MTR 1 U4

LD1117S33 1 U7

STG719STR 2 IC1 IC2

STMicroelectronics

STMicroelectronics

STMicroelectronics

STMicroelectronics

STMicroelectronics

STMicroelectronics

MEMS mic

MEMS mic

MEMS mic

MP34DT01

MP34DB01

MP45DT02

2 U12

2 U9

2 U3

STMicroelectronics

STMicroelectronics

STMicroelectronics

Solder for V3

Solder for V2

Solder for V1

28/30 DocID023502 Rev 2

AN4146 Revision history

Date

02-Oct-2012

Revision

1

22-Mar-2013 2

Table 6. Document revision history

Changes

Initial release.

Added audio hub demonstration board (STEVAL-MKI138V1) to application note

Updated

Section 1: Demonstration board and accessories

, added

Figure 3

Updated

Section 1.3: Microphone adapters

, updated

Figure 5

Updated

Section 2.2: Microphone audio adapter connections

, added

Figure 12

, updated

Figure 13

Updated

Section 3: Software settings

, added

Figure 14

, updated

Figure 15

,

16

,

17

DocID023502 Rev 2 29/30

AN4146

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Information in this document supersedes and replaces all information previously supplied.

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