Cirrus Logic CS4953xx - Manual (Page 21)

2-7 Copyright 2010 Cirrus Logic, Inc. DS732UM10
Slave Boot Procedures
CS4953xx Hardware User’s Manual
17. Read the APP_START message. If code execution is successful, the CS4953xx sends out an
APP_START message. This indicates that the code has been initialized and can accept further
configuration messages. The host should not attempt further communication with the CS4953xx until
the APP_START message has been read.
If the CS4953xx does not send an application start message, the host must return to Step 1.
18. Send Hardware Configuration messages. The master boot procedure is completed. The operating
system on the CS4953xx is now ready for host configuration of hardware and software.
Hardware configuration messages are used to define the behavior of the CS4953xx’s audio ports.
19. Send Software Configuration messages.The software configuration messages are specific to each
application. The application code User’s Guide for each application provides a list of all pertinent
configuration messages.
20. Send the KICKSTART message. The CS4953xx application locks the PLL and begins processing
audio after receiving this message.
2.3.2 Slave Boot
The Slave Boot procedure is a sequence in which the external host is the bus master and directly loads
the CS4953xx application code. The system host controller has each of the five communication modes
available, as specified in Table 2-1 . from either the serial control interface (SPI or I
2
C) or the parallel
control interface (Intel, multiplexed Intel, or Motorola modes). The boot messages used can be found in
Section 2.3.3 "Boot Messages" on page 2-10 . For information on how to configure the CS4953xx
overlays, such as hardware configuration messages, software configuration messages, and the kick-start
message, please refer to AN288, “CS4953xx/CS497xxx Firmware User’s Manual.”