
Symphony SoundBite Reference Manual, Rev. 2.0
4Freescale Semiconductor
Functional Blocks
Digital Signal Processor:
A DSPB56371 device (U1) comprises the bulk of the DSP functional block and sits at the heart of the
Symphony SoundBite development board. Positions 1 through 4 of SW2 are connected to the MOD pins
of the DSP and set the boot mode. An I2C serial EEPROM (U6), connected to the DSP through positions
5 and 6 of SW2, provides non-volatile data storage and allows the Symphony SoundBite to boot up and
run applicationsoftware in a stand-alone configuration (without a PC connected to download code). Audio
data in I2S format is transmitted through the DSP's ESAI port and received via the DSP's ESAI_1 port.
The balance ofthe DSPpinsare connected to anexpansion header (CON1), as well asto an8-position DIP
switch and to 9 LEDs for general purpose use.
The sytem clock is provided by two gates of U12 and a 24.576 MHz crystal. Power-on reset and manual
reset of the DSP and codecs is controlled by the reset manager (U11, U13) and the reset switch (SW3).
Audio Conversion:
The Audio Conversion functional block consists of three AK4556 devices (U2, U3, and U4) and one
AK4584 (U5) 24-bit codec. Digital audio data is transmitted and received in I2S format. The AK4584
generates the master left/right and bit clocks for all the codecs and the DSP's ESAI ports. Four stereo pairs
(or 8 mono channels) of analog audio input and output are provided at jacks J1–J8.
Digital audio input/output in optical S/PDIF format is supported by combination analog/digital jacks (J1,
J2) and an integrated digital audio receiver/transmitter in the AK4584 device. A built-in microphone is
connected to a fixed gain preamplifier (U14) which in turn is connected through jumper JP1 to the analog
inputs at jack J1. The microphone gain can be adjusted further through the internal amplifier within the
AK4584. The AK4584 is configured by the DSP over serial control lines connected to dedicated GPIO
pins on the DSP.
Debug/Communication Interface:
Debugging and communication between a host computer's USB port and the DSP is implemented using
the FT2232 multi-mode USB device (U7). Three modes of communication are permitted between the host
computer and the DSP: I2C, SPI and JTAG/OnCE. The communication mode is selected by software on
the host PC via the GPIO pins on the FT2232 device, which route the signal lines to the appropriate
peripheral on the DSP via buffer U9 (SPI and JTAG/OnCE) and analog switch U10 (I2C).
JTAG/OnCE is used for low-level debugging of the DSP. The SHI port on the DSP can be used for
high-level communication between the DSP and host PC using I2C or SPI protocol. The USB identity of
the FT2232 is provided by the serial EEPROM (U8). LED10, LED11, andLED12 indicate whichprotocol
is in use by the PC host application software.
Power Supply:
The Power Supply allows the Symphony SoundBite board to operate from an external power supply or
directly from a host computer's USB port. Note that when the Symphony SoundBite is powered only from
the USB port, AK4584 performance may not meet its data sheet specifications. For that reason, powering
the Symphony SoundBite board with an external supply is recommended and preferred.
Jumper JP3 selects the source for the board's power supply: external power via jack PWR_JACK (short
pins 1-2), power from the host computer's USB port (short pins 2-3). Alternately, if no pins of JP3 are
shorted, the Symphony SoundBite can be supplied with regulated 5V via pin 1 of the expansion connector
CON1.