AT2004 Datasheet, PDF (7/25 Pages) List of Unclassifed Manufacturers – 4 Channels ADPCM Processor with Echo Cancellation and Conferencing

AT2004
4 Channels ADPCM Processor with Echo Cancellation and Conferencing
Chip ID Setup
The two Chip ID pins A0 and A1 (Pins 6,7) should also be set during chip initialization. The “Chip ID” is used to differentiate between
AT2004 chips in a system that uses more than one AT2004 chip. When using only one chip, it is recommended to tie A0 and A1 to
digital zero. Thus, when programming the AT2004 chip, you can use the Chip ID = ‘00’ to substitute wherever you see A1, A0.
The maximum number of AT2004 can be used in a system is 4, and a chip ID must be assigned to each AT2004 in a system. The format
of A0 and A1 should be specified according to the following table:
A1 A0 Description
0 0 AT2004 chip ID=0
0 1 AT2004 chip ID=1
1 0 AT2004 chip ID=2
1 1 AT2004 chip ID=3
Programming the AT2004
Using the Serial Port to Input Commands
Commands for the AT2004 are entered using the 3-wire Serial Interface. The “three wires” refer to the three pins which control the
interface: SDI/SDO (Serial Data In/Serial Data Out), SCLK (Serial Clock), and SCSZ (Serial Chip Select). When SCSZ is enabled (low),
the SDI is sampled every SCLK signal. Sampled bits are collected into an 8-bit register and read by the DSP. The SCSZ signal can be
held more than 8-bits at a time in 8-bit multiples forming a COMMAND SEQUENCE. Different command sequences form the bulk of
AT2004 programming.
Byte 1
Generic 3-byte Command Sequence
Byte 2
Byte 3
SDI
LSB B1 B2 B3 B4 B5 B6 B7
SCLK
SCSZ
Command Sequence Overview
The AT2004 understands five different types of command sequences.
1. The PLL command sequences sets the operating speed of the chip.
2. The MCU7byte command sequence set the ADPCM algorithms, bit-slots, delay and EC’s reference channel number.
3. The Per Channel Control command sequence sets the echo canceling options and other options in the chip.
4. The Conferencing command sequence sets the conferencing channels.
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©2001 Atelic System, Inc