AN4146 Datasheet, PDF (1/30 Pages) Fairchild Semiconductor – Design Guidelines for Quasi-Resonant Converters

AN4146
Application note
STSmartVoice demonstration board STEVAL-MKI126Vx
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: I²S. 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 1
MEMS Digital
Microphone 6
SDA
SCL
STA321MP/MPL
1
PDM
Interface
6
Audio
Matrix
( Muxing/
Mixing )
I2C
PLL
Scalable
Microphone
Processor TM
Hardware
Accelerator
PWM
Serial Data
Output
I²S
Clock management
OUTxA
OUTxB
LRCK
BICK
SDAT 1/2/3
March 2013
DocID023502 Rev 2
1/30
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