Cirrus Logic CS4953xx - Manual (Page 25)

2-11 Copyright 2010 Cirrus Logic, Inc. DS732UM10
Slave Boot Procedures
CS4953xx Hardware User’s Manual
HCMB_PARALLEL is used when the application code is stored in external parallel ROM, such as an
external 8-bit or 16-bit EEPROM or Flash. The external data bus width is specified by the ‘M’ variable in
the first control word. Also, the 20-bit start address is specified in the second control word with the ‘A’
variable. Read cycle parameters can also be configured by the ‘x’ and ‘y’ variables. The
HCMB_PARALLEL message should be substituted for the HCMB_ message in
Figure 2-2 .
2.3.3.3 Host-Controlled Master Boot from I
2
C ROM
HCMB_I2C is used when the application code is stored in external I
2
C ROM, such as an I2C EEPROM.
The HCMB_I2C message should be substituted for the HCMB_ message in Figure 2-2 . This
boot mode can be configured to interface with many types of I
2
C ROMs. The 16-bit start address is
specified by the ‘A’ variable. The I
2
C clock is derived from the internal core clock. This clock can be
divided down with the ‘c’ 12-bit divider variable. The command byte (the first byte to the I
2
C ROM) can be
defined by the ‘s’ variable. The CS4953xx control port used for the HCMB_I2C can be configured by the
‘p’ variable.
2.3.3.4 Host-Controlled Master Boot from SPI ROM
HCMB_SPI is used when the application code is stored in external SPI ROM, either SPI EEPROM or SPI
Flash. The HCMB_SPI message should be substituted for the HCMB_ message in
Figure 2-2 .
This boot mode can be configured to interface with many types of SPI ROMs. The start address “A”
variable can be either 24-bit or 16-bit, configured by the “L” variable. Some SPI ROMs require some
‘dummy’ bytes after the address byte, before reading from the part, configurable by the ‘B’ variable.
Table 2-4. HCMB_I2C message for the CS4953xx
MNEMONIC VALUE
HCMB_I2C
1100 0000 000p cccc cccc cccc 0sss ssss
0000 0000 0000 0000 0000 0000 AAAA AAAA
Where
p = Serial Control Port Selection =1 for SCP2 (Normal Operation)
0 for SCP1 (Not Supported by O/S)
c = clock divider for I
2
C clock signal
s = 8-bit I
2
C command
A = 16-bit external memory start address
Table 2-5. HCMB_SPI message for CS4953xx
MNEMONIC VALUE
HCMB_SPI
1101 BBB0 0SSp cccc cccc cccc ssss ssss
L000 0000 AAAA AAAA AAAA AAAA AAAA AAAA
Where
B = number of dummy bytes sent after Address, before read
S = Chip Select
p = Serial Control Port Selection =
1 for SCP2
0 for SCP1,
c = SPI clock speed = DSP Core Clock/(c+2)
s = 8-bit SPI command
L = Address Length = 0 for 16-bit Address, 1 for 24-bit Address
A = 24/16-bit external memory start address