
ADAU1442/ADAU1445/ADAU1446
Data Sheet
Rev. D | Page 30 of 92
Self-Boot
load a program and a set of parameters that are saved in an
external EEPROM. Combined with the auxiliary ADC and the
multipurpose pins, this can potentially eliminate the need for a
microcontroller in a simple audio system. The self-boot sequence
acting as masters on the I2C bus on startup, which occurs when
The maximum necessary EEPROM size is 40,960 bytes, or
40 kB. This much memory is only needed if the program RAM
(4096 × 6 bytes) and parameter RAM (4096 × 4 bytes) are each
completely full.
A self-boot operation is triggered on the rising edge of RESET
when the SELFBOOT pin is set high, and it occurs after 10 ms
ADAU1446 read the program, parameter, and register data
have finished self-booting, additional messages can be sent to the
this typically is not necessary in a self-booting application. The
0x68 for a write and 0x69 for a read in this mode. The ADDRx pins
have different functions when the chip is in this mode; therefore,
the settings on them are ignored.
bus during a self-boot operation. Care should be taken that no
other device on the I2C bus tries to perform a write operation
generate SCL at 8 × fs; therefore, when fs,NORMAL is 48 kHz, SCL
runs at 384 kHz. SCL has a duty cycle of in accordance with
the I2C specification.
Chip Address 0xA1. The LSBs of the addresses of some EEPROMs
are pin configurable; in most cases, these pins should be tied
low to set this address. SigmaStudio writes to the EEPROM at
Address 0xA0.
EEPROM Format
The EEPROM data contains a sequence of messages. Each
discrete message is one of the four types defined i
n Table 17.Each message consists of a sequence of one or more bytes. The
first byte identifies the message type. Bytes are written MSB
first. Most messages are block write (0x01) types, which are
program RAM, parameter RAM, and control registers.
The body of the message following the message type should
start with two bytes indicating message length and then include
a byte indicating the chip address. Following this is always a
2-byte register or memory address field, as with all other
control port transactions.
SigmaStudio is capable of generating the EEPROM data necessary
function called write latest compilation to E2PROM. This function
Table 16. Functions of the Control Port Pins
Pin
I2C Mode
SPI Mode
Self-Boot
SCL/CCLK
SCL—input
CCLK—input
SCL—output
SDA/COUT
SDA—open collector output
COUT—output
SDA—open collector output
ADDR1/CDATA
ADDR1—input
CDATA—input
Unused input—tie to ground or power
CLATCH
Unused input—tie to ground or power
CLATCH—input
Unused input—tie to ground or power
ADDR0
ADDR0—input
Unused input—tie to ground or power
Table 17. EEPROM Message Types
Message ID
Message Type
Following Bytes
0x00
End
None
0x01
Write
One byte indicating message length (including chip address and
subaddress), one byte indicating chip address, two bytes indicating
subaddress, and an appropriate number of data bytes
0x02
Delay
Two bytes for delay
0x03
No op
None