3

ATSAM3308

6090A–DRMSD–08/04

allowing inter P24 communication at the current sampling rate. Slots 0 to 7 are reserved

for a specific router DSP, which also handles audio out, audio in, and remix send.

Async Bus

The Async Bus has 24-bit data inside the chip and 16-bit data outside.

The P16 processor normally masters the Async Bus; it can read/write the P24 memories

and the external or embedded ROM/RAM. However, each P24 can request a bus mas-

ter cycle for accessing external ROM/RAM or other P24 memories. This allows efficient

intercommunication between several P24s on asynchronous block basis. Specific P24

instructions FLOAT and FIX convert fixed-point DSP data to floating-point 16 bits. This

allows for 20-bit audio dynamic range when using 16-bit external memory.

16-bit Processor

The P16 processor is widely used in ATSAM products. Using the P16 keeps large firm-

ware investments from the ATSAM97xx series. A built-in ROM, connected to the P16

holds basic input/output software (BIOS) for peripherals such as UART, DataFlash,

SmartMedia and MPU, as well as a debugger that uses a dedicated asynchronous serial

line. The firmware can reside on external parallel ROM/Flash or it can be downloaded at

power-up into the built-in 16k x 24 RAM from serial EEPROM, DataFlash, SmartMedia

or host.

MMU (Memory

Management Unit)

The MMU handles transfer requests between the external or embedded RAM/ROM, the

P16 and the P24s through the Async Bus. The ATSAM3308 includes 16k x 24 RAM on

chip.

Router: Final ACC, MIX,

Audio Out, Audio In

This block includes RAM (accessed through the Async Bus) that defines the routing

from the Sync Bus to/from the Audio I/O or back to the Sync Bus (mix send). It takes

care of mix and accumulation from Sync Bus samples. Eight channels of audio in and

eight channels of audio out are provided (4-stereo in/out, I2S format). The stereo audio

in channels may have a different sampling rate than the audio out channels. In this case,

one (or more) P24 takes care of sampling rate conversion.

I/O

The ATSAM3308 includes very versatile I/Os, that share common pins for reduced pin

count and small IC footprint. Most I/Os, when not used for a specific function, remain

available as firmware controlled general-purpose pins.

The following peripherals are included on chip:

•

2 x 8-bit timers

•

2 x 16-bit timers

•

Parallel slave 8-bit port, MPU401 compatible

•

Parallel master 8-bit port, for connection to SmartMedia and/or LCD display,

switches, etc.

•

2 x asynchronous bidirectional serial ports

•

Synchronous serial slave port (SPI type host connection).

•

SPI master bidirectional port for EEPROM or DataFlash connection.

•

Firmware controlled I/O pins.