ADAU1442/ADAU1445/ADAU1446
Data Sheet
Rev. D | Page 26 of 92
CONTROL PORT
Overview
three control modes: I2C control mode, SPI control mode, or
self-boot mode (no external controller).
SPI control port and a 2-wire I2C bus control port. Each can be
used to set the RAMs and registers. When the SELFBOOT pin
is low at power-up, the chip defaults to I2C mode but can be put
into SPI control mode by pulling Pin CLATCH low three times.
When the SELFBOOT pin is set high at power-up, th
e ADAU1442/register settings from an external EEPROM at startup.
The control port is capable of full read and write operations for
all memories and registers, except for those that are read only.
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 registers.
All addresses can be accessed in either a single-word 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
being written.
The first byte (Byte 0) of a control word contains the 7-bit chip
address plus the R/W bit. The next two bytes (Byte 1 and Byte 2)
together form the subaddress of the memory or register location
must be two bytes because the memory locations within the
and their sizes exceed the range of single-byte addressing. All
subsequent bytes (starting with Byte 3) contain the data, such as
control port data, program data, or parameter data. The exact
formats for specific types of writes are shown in
Figure 13 and
mechanisms for updating signal processing parameters in real
time without causing pops or clicks in the output. In cases
where large blocks of data must be downloaded, the output of
the DSP core can be halted, new data can be loaded, and then
the output of the DSP core can be restarted. This is typically
done during the booting sequence at startup or when loading a
new program into RAM. In cases where only a few parameters
must be changed, they can be loaded without halting the program.
A software-based safeload mechanism is included for this purpose,
and it can be used to buffer a full set of parameters (for example,
the five coefficients of a biquad) and then transfer these parameters
into the active program within one audio frame.
The control port pins are multifunctional according to the mode in
which the part is operating
. Table 16 details these functions.
I2C Port
serial (I2C-compatible) microprocessor bus driving multiple
peripherals. Two pins, serial data (SDA) and serial clock (SCL),
ADAU1446 and the system I2C master controller. In I2C mode, bus, which means that the parts cannot initiate a data transfer.
Each slave device is recognized by a unique address. The address
ADAU1446 have eight possible slave addresses: four for writing
operations and four for reading. These are unique addresses for
Users can communicate with these addresses by using the USBi
communication channel list in the hardware configuration tab
of SigmaStudio. 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. Address Bit 5 and
Address Bit 6 are set by tying the ADDRx pins of th
e ADAU1442/SDA and SCL should have pull-up resistors on the lines connected
to them (a standard value is 2.0 k, but this can be changed
depending on the capacitive load on the line). The voltage on
these signal lines should not be greater than the voltage of
IOVDD (3.3 V).
Sequence
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
0
1
0
ADDR1
ADDR0
R/W
Addresses
ADDR1
ADDR0
Slave Address
0
0x70
0
1
0x71
0
1
0
0x72
0
1
0x73
1
0
0x74
1
0
1
0x75
1
0
0x76
1
0x77
1
0 = write, 1 = read.
Addressing
Initially, all devices on the I2C bus are in an idle state, in which
the devices monitor the SDA and SCL lines for a start condition
and the proper address. The I2C master initiates a 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 or
an address and data stream 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