CS49310 datasheet(61/86 Pages) CIRRUS

61 / 86 page

CS49300 Family DSP

DS339PP4

8.3.1. Design Considerations when using

GFABT Codes

The designer should be aware that the gfabt codes

do not lock the PLL, so therefore the actual time in-

volved with autobooting is subject to the open loop

VCO frequency. The PLL is only locked when the

command is sent from the host, typically along

with the kickstart command. Also, the designer

should take into account the access time of the

Flash Memory, EPROM, and latches used in their

specific design. While there is a temptation to use

the gfabt4 code which would theoretically mini-

mize the Autoboot time, the designer should realize

that this may result in the DSP to attempting to Au-

toboot too quickly, resulting in clocking times that

exceed that of the specified access times of partic-

ular external memory devices or the associated

latches.

The designer should note that the times listed in

Table 11 were taken from 3 sample CS493264-CL

Rev. G devices and are in no way a guarantee of the

times that your design will achieve as all values are

dependent on the open loop frequency of the DSP.

Furthermore the times listed in Table 11 DO NOT

include the code initialization time (the time spent

after download while the code prepares for

messages). Therefore, the times listed above should

be used as the upper bound on boot time when

using the gfabt codes.

8.4. Internal Boot

Certain applications are stored in the ROM of the

CS493253, CS493254, CS493263 and CS493264.

To enable these applications a special loader called

an internal boot assist program must be used. This

internal boot assist (or IBA) code can be

downloaded using either host boot or autoboot

methods. After the IBA program has been

downloaded, it enables the internally stored

application code. The IBA codes are typically

around 350 bytes in size and hence can easily be

stored in a host controller.

8.5. Application Failure Boot Message

Each piece of application code is specifically

tailored for an individual part in the CS493XX

family. Although it is possible to load a piece of

code

into

the

wrong

chip

and

receive

BOOT_SUCCESS byte, the code will not initialize

itself. In order to facilitate the debug of designs

which can accept many members of the CS493XX

family, an APPLICATION_FAILURE message is

provided.

As mentioned earlier, the host must wait for at least

5ms after download before sending configuration

messages to the CS493XX. This provides time for

the code to initialize itself. If the INTREQ pin is

low after the download process has completed, the

host should read from the CS493XX. The byte

0xF0 indicates APPLICATION_FAILURE. This

byte informs the host that the application code was

loaded into an incompatible DSP.

Although most of the messages listed in Tables 9

and 10 are essentially ignored for autoboot, it

should

noted

that

the

APPLICATION_FAILURE message is applicable

whether host boot or autoboot is used.

8.6. Resetting the CS493XX

Resetting the CS493XX uses a combination of

software and hardware. To reset the device, a

previous application must have been downloaded.

The flow diagram in Figure 39, "Performing a

Reset" on page 62 shows the procedure for

performing a reset.

The following is a detailed description of a reset

sequence to the CS493XX. All writes and reads

with the CS493XX should follow the protocol

given in Section 6, “Control” on page 32.

1) Reset begins when the host issues a hard reset

and holds the mode pins appropriately (WR,

RD, and PSEL) as described in Section 6,

“Control” on page 32. It is assumed that the

communication

protocol

followed

for

CS49310 数据表(PDF) 61 Page - Cirrus Logic

CS49310 数据表(HTML) 61 Page - Cirrus Logic

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

数据表下载