EVAL-ADAU1701EB AD [Analog Devices], EVAL-ADAU1701EB Datasheet - Page 19

• Manufacturer Part Number: EVAL-ADAU1701EB
• Description: SigmaDSP 28/56-Bit Audio Processor with 2ADC/4DAC
• Manufacturer: AD [Analog Devices]

Preliminary Technical Data
CONTROL PORT
OVERVIEW
The ADAU1701 can operate in one of three control modes:
The ADAU1701 has both a 4-wire SPI control port, and a 2-
wire I
RAMs and registers. When selfboot mode is not selected at
power-up, the part defaults to I
control mode by pulling pin CLATCH/WP low three times.
When the SELFBOOT pin is set high, the ADAU1701 will load
its program, parameters, and registers settings from an external
EEPROM on start-up.
The control port is capable of full read/write operation for all of
the memories and registers. Most signal processing parameters
are controlled by writing new values to the parameter RAM
using the control port. Other functions, such as mute and
input/output mode control, are programmed by writing to the
control registers.
All addresses may be accessed in both a single-address mode or
a burst mode. A control word consists of the chip address, the
register/RAM subaddress, and the data to be written. The
number of bytes per word depends on the type of data that is
written.
The first byte of a control word (Byte 0) contains the 7-bit chip
address plus the R/W bit. The next two bytes (Bytes 1 and 2)
together form the subaddress of the memory or register
location within the ADAU1701. This subaddress needs to be
two bytes because the memories within the ADAU1701 are
directly addressable, and their sizes exceed the range of single-
byte addressing. All subsequent bytes (Bytes 3, 4, etc.) contain
the data, such as control port data or program or parameter
data. The exact formats for specific types of writes are shown in
Table 27 to Table 35.
The ADAU1701 has several mechanisms for updating signal
processing parameters in real time without causing pops or
clicks. In cases where large blocks of data need to be down-
loaded, the output of the DSP core can be halted (using Bit x of
the core control register), new data loaded, and then restarted.
This is typically done during the booting sequence at start-up or
when loading a new program into RAM. In cases where only a
few parameters need to be changed, they can be loaded without
halting the program. To avoid unwanted side effects while
loading parameters on the fly, the SigmaDSP provides the
safeload registers. The safeload registers can be used to buffer a
full set of parameters (e.g. the five coefficients of a biquad) and
•
•
•
2
C bus control port that can each be used to set the part’s
I
SPI Control
Selfboot (no external controller)
2
C Control
2
C mode, but can be put into SPI
Rev. PrF | Page 19 of 43
then transfer these parameters into the active program within
one audio frame. The safeload mode uses internal logic to
prevent contention between the DSP core and the control port.
The control port pins are multi-functional according to which
mode in which the part is operating. details these different
functions.
I
The ADAU1701 supports a 2-wire serial (I
microprocessor bus driving multiple peripherals. Two pins,
serial data (SDA) and serial clock (SCL), carry information
between the ADAU1701 and the system I
In I
means that it will never initiate a data transfer. Each slave device
is recognized by a unique address. The address byte format is
shown in Table 15. The ADAU1701 has four possible slave
addresses: two for writing operations and two for reading.
These are unique addresses for the device and are illustrated in
Table 16. The LSB of the byte sets either a read or write
operation; Logic Level 1 corresponds to a read operation, and
Logic Level 0 corresponds to a write operation. The sixth and
seventh bits of the address are set by tying the ADDRx pins of
the ADAU1701 to logic level 0 or logic level 1. Both SDA and
SCL should have 2.2 kΩ pull-up resistors on the lines connected
to them. The voltage on these signal lines should not be above
IOVDD (3.3 V).
Table 15. ADAU1701 Address Byte Format
Bit 0
Table 16. ADAU1701 I
ADDR1
0
0
0
0
1
1
1
1
Addressing
Initially, all devices on the I
where the devices monitor the SDA and SCL lines for a start
condition and the proper address. The I
data transfer by establishing a Start condition, defined by a
high-to-low transition on SDA while SCL remains high. This
indicates that an address/data stream will follow. All devices on
the bus respond to the start condition and shift the next eight
bits (7-bit address + R/ W bit) MSB first. The device that
recognizes the transmitted address responds by pulling the data
2
C PORT
0
2
C mode the ADAU1701 is always a slave on the bus, which
Bit 1
1
ADDR0
0
0
1
1
0
0
1
1
Bit 2
1
Read/Write
0
1
0
1
0
1
0
1
Bit 3
2
C Addresses
0
2
C bus are in an idle state, which is
Bit 4
1
Bit 5
ADDR1
2
C master initiates a
2
C master controller.
2
C compatible)
Slave Address
0x68
0x69
0x6A
0x6B
0x6C
0x6D
0x6E
0x6F
ADAU1701
Bit 6
ADDR0
Bit 7
R/W