CS49310 datasheet(60/90 Pages) CIRRUS

60 / 90 page

CS49300 Family DSP

DS339F7

more detailed description of the different hardware

configurations can be found in Section 11,

“Hardware Configuration” on page 74.

The software configuration messages are specific

to each application. The software user’s guides

(AN163, AN163x, AN162, AN162x) for each

application code provides a list of all pertinent

configuration messages. Writing the KICKSTART

message to the CS493XX begins the audio

decode process. The KICKSTART message will

also be described in the user’s guide for each

application. Until the KICKSTART has been sent,

the decoder is in a wait state.

8.2.1. Autoboot INTREQ Behavior

It is important to note that ABOOT and INTREQ

are multiplexed on pin 20 of the CS493XX.

Because this pin serves as an input before reset,

and an output after reset, the host should release

the ABOOT line after RESET has gone high. As

shown in Figure 37, "Autoboot INTREQ Behavior"

on page 60, the host must drive ABOOT low

around the rising edge of RESET.

After the host has released the ABOOT line, it will

remain high while the DSP prepares to load code

from the external memory. INTREQ should be

ignored during download, i.e. interrupts should be

masked on the host. The download time will vary

according to the size of the download image and

the frequency of the main DSP clock. The autoboot

sequence is specified to complete within 200 ms

(from the rising edge of RESET). Note: This time

has been tested using the ac3_493263_13.ld

application

code

release,

however

other

application code releases MAY take longer than

200mS as they have may an increased image size

and may take longer to initialize all of the internal

state variables. It is up to the designer to verify the

actual times required for each application code in

their system.

RESET

ABOOT

Trstsu

Trsthld

Driven Low by Host

Driven Low by CS492X

Download in Progress

Figure 37. Autoboot INTREQ Behavior

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