CS4811 Cirrus Logic, CS4811 Datasheet - Page 14

• Manufacturer Part Number: CS4811
• Description: Fixed Function Multi-Effects Audio Processor
• Manufacturer: Cirrus Logic

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3.5
The serial control port is used for self-booting from
an external EEPROM and supports both the SPI
bus and the I
face is selected via the SPI/I
pled during de-assertion of the RST pin.
3.5.1
The SPI bus interface consists of 4 digital signals,
CCLK, CDIN, CDOUT and CS. CCLK, the control
port bit clock, is used to clock individual data bits.
CDIN, the control data input, is the serial data input
line to the CS4811. CDOUT, the control data output,
is the output data line from the CS4811. CS, the chip
select signal, is asserted to enable an external SPI
port. Data is clocked in on the rising edge of CCLK
and clocked out on the falling edge.
3.5.1.1
The SPI master mode is designed for read-only op-
eration during self-booting from a serial EEPROM.
A typical self-boot sequence with a Xicor X25650 se-
rial EEPROM, or equivalent, is shown in Figure 9. On
exit from reset, the CS4811 asserts CS. The 8-bit read
instruction (00000011) is sent to the EEPROM fol-
lowed by a pre-defined 16-bit start address. The
14
CDOUT
CDIN
CLK
Serial Control Port
CS
SPI Bus
SPI Mode
2
C
®
0
MSB
bus interfaces. The desired inter-
0 0
1
2
COMMAND
0
READ
3
0
Figure 9. Control Port Timing, SPI Master Mode Self-Boot
4
0
2
5 6
C pin, which is sam-
0 1 1
7
8
0 0
ADDRESS = 0X0000
9 10 11
0 0
16-BIT
21 22 23 24
0 0 0
7 6
CS4811 then automatically clocks out sequential
bytes from the EEPROM until the last byte has
been received. These bytes include initialization
and configuration data for the device along with the
application firmware code. After the last byte is re-
ceived, the CS4811 deasserts CS and begins program
execution. At this point, the serial control port be-
comes inactive and cannot be accessed.
3.5.2
The I
consists of 2 digital signals, SCL and SDA. SCL or
serial clock, is used to clock individual data bits.
SDA or serial data, is a bidirectional data line. Two
additional pins, AD1 and AD0, are inputs which
determine the 2 lowest order bits of the 7-bit I
device address and should be tied to ground.
3.5.2.1
The I
eration during self-booting from a serial EEPROM.
A typical self-boot sequence with a Microchip
X24256 serial EEPROM, or equivalent, is shown
in Figure 10. On exit from reset, the CS4811 sends
an initial write preamble to the EEPROM which
consists of a I
25 26 27 28 29
5
DATA
4
2
2
C bus interface implemented on the CS4811
C master mode is designed for read-only op-
3 2 1 0
I
2
I
30 31
C Bus
2
C Mode
2
C start condition and the slave ad-
7 6
5
DATA + n
4
3 2 1 0
CS4811
DS486PP2
2
C