ON Semiconductor BELASIGNA R262 BR262PMEVK, BelaSigna R262, BR262PMEVK User Manual

BR262PMEVK

BELASIGNA) R262
Prototyping Module
Evaluation Board
User'sManual

The BelaSigna R262 Prototyping Module

The BelaSigna R262 prototyping module is a miniature,
self-contained unit that can be integrated into a product or
prototype to evaluate the performance of BelaSigna R262
“in-form-factor”.

Key Features

The module is shown in Figure 1 and features:

 A Miniature Size of only 22 mm  6mm
 The 30-ball WLCSP Version of BelaSigna R262

(BR262W30A103E1G)

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EVAL BOARD USER’S MANUAL

 Two MEMS Microphones Spaced 10 mm Apart

(Knowles Part Number SPU0410HR5H−PB)

 Through-hole Test Points for External Connections
 Configured to Boot Directly to the ROM Application

Using the Internal Clock

2

 I

C and GPIO Signals Available on Test Points

 An Onboard I

Application

2

C EEPROM for Optional Custom

Dual MEMS

Microphones

Figure 1. BelaSigna R262 Prototyping Module

Default Configuration

The prototyping module configures BelaSigna R262 to
run off its internal oscillator and to boot directly into the
ROM-based noise reduction algorithm. The module is
pre-configured to simultaneously output two different
algorithm turnings: a pure close-talk output on AO0, and an
output that is close-talk mixed 60% towards far-talk on
AO1. All that is required is to supply the module with 1.8 to

Through-hole Test

points

BelaSigna R262

3.3 VDC (requires approximately 20 mA), and to connect
the analog outputs to your in-form-factor design. Power is
connected to VBAT (+) and GND (−). The prototyping
module configures the ROM application as summarized in
Table 1 when power is applied.

A description of all test points and a complete schematic

and layout is available in Appendix A.

 Semiconductor Components Industries, LLC, 2012

December, 2012 − Rev. 0

1 Publication Order Number:

EVBUM2166/D

BR262PMEVK

Table 1. BelaSigna R262 PROTOTYPING MODULE LSAD CONFIGURATION

Pin Name Preset Description

CLOCK_SEL (SPI_CLK/GPIO0) 7 Internal Clock

BOOT_SEL (SPI_CS/GPIO1) 4 Active Mode

CHAN_SEL (SPI_SERO/GPIO2) 3 Dual Output Noise Reduction

ALPHA_SEL (SPI_SERI/GPIO3) 4 Mixer set 60% between Start and End of Range

Talk Distance Selectable between Close-talk and Far-talk

(5 cm – 500 cm)

(Two Single-ended Analog Outputs)

Channel 0 as per BOOT_SEL “Start of Range” (Close-talk)

Channel 1 as per BOOT_SEL and ALPHA_SEL

Connecting the Prototyping Module

The analog output signals are available on AO0 (6),
AO1 (7), and GNDA (−). An optional momentary
push-button control can be connected between GP5 (5) and
GNDD (−) that can be used to swap the two processed
outputs between AO0 and AO1. The pinout for the module,
along with typical connections are illustrated in Figure 2.
The analog outputs of the device can be connected to your
system’s analog inputs as single-ended signals using AO0
and GNDA and/or AO1 and GNDA. If the module is
re-configured to output a mono, differential analog output
by changing the CHAN_SEL resistors R4 and R5, via I

2

commands, or by loading a custom application, you can

GND

1.8 to 3.3 VDC

connect AO0 and AO1 to your system as a differential
analog signal.

NOTE: The analog output impedance is 3 kW and is intended to drive

a high-impedance (line-level) input, not speakers nor
headphones directly. Refer to the BelaSigna R262 datasheet
for more information on output stage characteristics.

You can also use the prototyping module as a digital
microphone replacement outputting a stereo DMIC signal
on test point GP4 (4), provided you supply an appropriate
DMIC clock signal on the CLK (8) test point and
re-configure the module’s CLOCK_SEL resistive divider to

C

match the provided clock frequency. Refer to the
BelaSigna R262 datasheet for more information.

Analog Output 1
Analog Output 0
Analog GND

Swap Channels

Figure 2. BelaSigna R262 Prototyping Module Typical Connections

Operating the Prototyping Module

The default configuration of the prototyping module
provides the widest noise reduction adjustment range
(close-talk to far-talk) by selecting preset 4 on the
BOOT_SEL input, and is pre-configured to simultaneously
output two different algorithm tunings: a pure close-talk
output on AO0, and an output that is close-talk mixed 60%
towards far-talk on AO1. The processed outputs from these
two algorithm tunings are available as single-ended analog
outputs on AO0 – GNDA, and AO1 – GNDA. The
application will swap the output channels when GP5 is
momentarily pulled low. If a momentary push-button is
connected between GP5 and GNDD, pressing and releasing

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this button will swap the two processed outputs between
AO0 and AO1.

Close-Talk

Close-talk mode aggressively filters noise and manages
gain to pick up speech within 5 to 10 cm from the
microphone array, effectively attenuating both speech and
noise that is farther away. This mode is suitable for mobile
handsets and radios where the speech source is very close to
the microphones and the noise level can be quite high; up to
90 dB SPL. Noise reduction performance in this mode
ranges from 20 to 30 dB SNR improvement (SNR−I),
depending on the type of noise.

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BR262PMEVK

Close-Talk Mixed 60% Towards Far-Talk

The second, mixed mode of close-talk mixed 60%
towards far-talk is similar to the core near-talk mode and
features excellent noise reduction in applications where the
speech source is located slightly further away from the
microphones; typically 50 to 100 cm. This mode is suitable
for handsfree devices and performs well in noise levels up
to 70 dB SPL. Expected noise reduction performance in this
mode is 10 to 20 dB SNR−I, depending on the type of noise.

Refer to the AND9109/D − BelaSigna R262 Getting
Started Guide for details on the different algorithm modes
and performance metrics.

Module Positioning

The speech source can come from any direction (normally
in front of the microphones), as long as it is within the
“working sphere” of the current algorithm mode. For
close-talk mode, the mouth reference point (MRP) should be
located between 5 and 10 cm from the microphones.

For close-talk mixed 60% towards far-talk, the MRP
should be located between 50 and 100 cm from the
microphones.

Acoustic Design

If the prototyping module is replacing an existing
microphone, the old microphone should be removed and the
module should be mounted as close as possible to the
original microphone location.

The device casing should be modified or manufactured
such that there is an appropriate acoustic path to the two
microphones on the module. Two holes roughly 0.5 to 1 mm
in diameter should be drilled in the casing 10 mm apart
above the sound ports of the onboard microphones. If
possible a rubber or foam isolation gasket should be installed
between the microphones and the device casing.

Electrical Considerations

The analog output(s) of the module can be connected
directly to any existing microphone input but keep in mind
that it may be necessary to lower any existing microphone
pre-amplification.

Care should be taken to properly shield the module and the
analog outputs if your product involves radio frequencies.
Use coaxial or shielded cable when connecting the analog
outputs of the module, and if necessary, wrap the module
with foil tape.

Customizing the Prototyping Module

If you would prefer to have the default tunings to be
something other than close-talk and close-talk mixed 60%
towards far-talk, you can change the values of the resistive
dividers on the BOOT_SEL (R3 and R4) and ALPHA_SEL
(R7 and R8) inputs. A component placement diagram
showing the locations of the various resistors is illustrated in
Figure 3. Refer to the BelaSigna R262 datasheet for more
information on BOOT_SEL and ALPHA_SEL inputs, and
the resistive divider values required to achieve specific
presets.

If you would like to re-configure the module to use the
DMIC interface, you must supply an appropriate DMIC
clock signal on the CLK test point and re-configure the
module’s CLOCK_SEL resistive divider (R1 and R2) to
match the provided clock frequency. A stereo DMIC signal
will be output on test point GP4. Refer to the
BelaSigna R262 datasheet for more information on the
supported DMIC clock frequencies, and the resistive divider
values required to select them.

If you would like to re-configure the module to output a
differential analog signal, you must adjust the resistive
dividers on the CHAN_SEL input (R5 and R6) to select
preset 0 or preset 5. Refer to the BelaSigna R262 datasheet
for more information on the CHAN_SEL input and the
resistive divider values required to achieve specific presets.

If you would like to re-configure the module to load a
custom application from the EEPROM, you must load a
valid custom application onto the EEPROM and remove
resistor R4 to have the module boot from EEPROM. Refer
to the BelaSigna R262 datasheet for more information on the
BOOT_SEL input and the resistive divider values required
to achieve specific presets. Contact your local
ON Semiconductor support representative for more
information about custom applications.

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BR262PMEVK

APPENDIX A

For your convenience, the prototyping module has many

test points. Signals that are intended to be interfaced to

external devices are provided on through-hole test points.
All of the available test points are summarized in Table 2.

Table 2. BelaSigna R262 PROTOTYPING MODULE TEST POINT DESCRIPTIONS

Test Point Name Designator Description

VBAT + Main Module Power Supply (1.8 to 3.3 VDC, 20 mA)

SCL 2 I2C Clock

SDA 1 I2C Data

GND − Main Module Ground

AO1 7 Channel 1 Analog Output

AO0 6 Channel 0 Analog Output

GNDA − Analog Ground (Internally Connected to GND)

VDDA Internal 2.0 V Power Supply

VDDD Digital Power Supply (Internally Generated)

GNDD − Digital Ground (Internally Connected to GND)

CLK 8 Optional Input Clock

TP2 Microphone 1 Test Point

VREG Internal 1.0 V Power Supply

TP1 Microphone 0 Test Point

GP5 5 Optional GPIO Input (SWAP_CHAN)

GP4 4 Optional DMIC Output

TP3 3 Reset

Figure 3. Component Placement Diagram

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BR262PMEVK

Figure 4. BelaSigna R262 Prototyping Module Schematic

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5

BR262PMEVK

Figure 5. BelaSigna R262 Prototyping Module Layout

(View from Top to Bottom)

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or services visit our Web site at www.onsemi.com

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