5 softboot, 1 softboot messaging, 2 softboot procedure – Cirrus Logic CS485xx User Manual

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Softboot

CS485xxr Hardware User’s Manual

DS734UM7

2-8

2.5 Softboot

The O/S application code for the

CS485xx

allows users to swap out one or more overlays during run time,

without the need for re-download of the entire overlay stack. This is helpful for reducing the time required for
switching between different types of incoming audio data streams.

The Softboot procedure includes initial messaging that sends the

CS485xx

into a boot state where the host

can boot the

CS485xx

with different overlays according to the boot methods described in this chapter. This

includes a soft reset of the

CS485xx

, which then requires that the host send or re-send the hardware and

software configuration messages.

2.5.1 Softboot Messaging

Two messages are relevant to the softboot procedure for the

CS485xx

. These messages are: SOFTBOOT

and SOFTBOOT_ACK.

The SOFTBOOT message is sent from the host controller to the

CS485xx

to indicate to the

CS485xx

that the

system requires swapping of overlays.

The SOFTBOOT_ACK is sent from the

CS485xx

to the host controller to indicate that the host can now boot

the

CS485xx

with the new overlays.

2.5.2 Softboot Procedure

Figure 2-4

describes the Softboot procedure. This is a step-by-step guideline that can be used as an aid in

developing the system controller code required to drive the

CS485xx

Table 2-6. SOFTBOOT Message

Mnemonic

Value

SOFTBOOT

0x81000009

0x00000001

Table 2-7. SOFTBOOT_ACK Message

Mnemonic

Value

SOFTBOOT_ACK

0x00000005