BelaSigna R281
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7
System Performance
Recognition Rate
Performance has been measured in various noise
conditions and is shown in Figure 3. Tests were performed
in a sound isolation booth with a series of pre−recorded
trigger and non−trigger phrases playing continuously, mixed
with varying levels of noise. Recognition rate is 100% in a
quiet environment (no noise playing). The system was
trained in a quiet environment. In all cases, the false trigger
rate (the number of times the system triggered on a
non−trigger phrase) was 0%.
Figure 3. Recognition Rate Versus SNR
Current Consumption
Average current consumption was also measured with the device operating in a pure noise environment with no speech
present. The results are presented in Table 9.
Table 9. AVERAGE CURRENT CONSUMPTION
Condition Average Current Consumption (uA), VBAT = 1.8 V
Quiet Environment 160
Babble Noise 170
*Not including microphone current consumption
Single User Operation
Because BelaSigna R281 performs recognition based on
a training procedure performed by a specific individual,
recognition of the trigger phrase is effectively
“single−user”. Only the person who trained the system (or
an individual with an extremely similar voice print) will be
able to reliably trigger the device.
Digital Interfaces
Wake Up Pin
The Wake Up pin is a digital output (referenced to VDDO)
which is used to indicate that the trigger phrase was detected.
It is intended to be connected to a digital input of an external
host, and its behavior (active high versus active low and
duration) is configurable via I
2
C.
For more information refer to AND9267/D.
Boot Select Pin
This pin is reserved for future purpose and must be
connected to VDDA.
Inter*IC Communication (I
2
C) Interface
The I
2
C interface is an industry−standard interface that
can be used for high−speed transmission of data between
BelaSigna R281 and an external device. The interface
operates at speeds up to 100 Kbit/sec, and always operates
in slave mode at an address of 0x62.
