R261 Datasheet, PDF (15/28 Pages) ON Semiconductor – Advanced Noise Reduction Solution for Voice Capture Devices

BelaSigna R261
Digital Control, Hardware Configuration and Interfaces
Boot Control
The BOOT_SEL pin controls the booting method of
At power−on−reset, BelaSigna R261 will normally _{BelaSigna R261. There are in fact two alternate methods to}
execute the application stored in ROM with the default _{boot a custom application or hardware/algorithm}
hardware and algorithm configuration. Additional built−in configuration. These methods, along with the default boot
hardware and algorithm configuration options are available _{method, are described in Table 9. Note that the BOOT_SEL}
as described later in this section by using the CONFIG_SEL _{pin is not available on the WLCSP−26 package option,}
and ATT_SEL pins. These settings are selected at boot−time _{consequently, this signal is left floating and the automatic}
based on the pin voltage levels.
boot selection described below applies for all applications
using this reduced ball package variant.
Table 8. BOOT CONTROL OPTIONS
Boot Method
Condition
EEPROM Boot
(Automatic boot selection)
BOOT_SEL high
(or floating/not
available on package)
LSAD Boot
I²C Boot
BOOT_SEL low
Connect to BelaSigna
R261 via I²C after
default boot−up
Description
Enables SPI interface and attempts to boot from external EEPROM. EEPROM
may contain a custom application or configuration. If no EEPROM, or bad
content, loads the default application in ROM with hardware and algorithm
configuration determined by CONFIG_SEL and ATT_SEL pins. See the “Be-
laSigna R261 Configuration and Communications Guide” for more information.
Loads default application in ROM. Hardware and algorithm configuration de-
termined by CONFIG_SEL and ATT_SEL pins.
The I²C control interface can be used to download a custom application, or to
re−configure the default application. See the “BelaSigna R261 Configuration
and Communications Guide” for more information.
When the automatic boot selection process is being used,
either when selecting the 26−ball package version, or simply
when leaving the BOOT_SEL pin unconnected on the
application PCB, it is very important to ensure that the SPI
pins will not be driven by any external hardware component.
Typically, a custom application may want to use the PCM
interface, which is also multiplexed with the SPI port.
Extreme care must be taken in such use cases, to ensure that
the SPI ports remain at high impedance during the boot
process. Contact your local technical support for more
information on this particular use case.
Reset
BelaSigna R261 can be forced to execute a
power−on−reset by pulling the NRESET pin to ground for
at least 100 ns. Note: NRESET is not available on the
26−ball WLCSP package.
Algorithm Control
BelaSigna R261 has provisions to control whether the
noise reduction algorithm processed signal is output, or an
unprocessed signal is output. This effectively enables or
disables the algorithm. The algorithm can be controlled via
the I²C interface or by use of the ALGO_CTRL pin. When
using the ALGO_CTRL pin, the algorithm state is toggled
whenever the digital signal transitions to low and stays low
for at least 10 ms, as shown in Figure 6. The actual transition
between algorithm enable/disable states can occur at any
time during the 10 ms low period of the signal.
10 ms (min)
10 ms (min)
ALGO_CTRL
Algorithm State
Enabled
Disabled
Figure 6. ALGO_CTRL Timing Diagram
Enabled
BelaSigna R261 has two processing channels (Channel 0
and Channel 1), when the noise reduction algorithm is
enabled, Channel 0 contains the processed signal and
Channel 1 contains the unprocessed signal. The effect of
toggling the algorithm state is to swap Channel 0 and
Channel 1, i.e. disabling the algorithm causes Channel 0 to
contain the unprocessed signal and Channel 1 to contain the
processed signal. These two output channels represent the
internal DSP output signals with BelaSigna R261. The
DMIC and analog audio outputs can each be configured to
use either channel. See the Output stage section to see how
Channel 0 and Channel 1 are used by the various
configuration options of BelaSigna R261’s output stage.
Sleep Control
As described in the modes of operation, there are multiple
methods to enter and exit from Sleep mode. Each of these
methods is meant to be used independently, i.e. methods of
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