CS49310 datasheet(64/86 Pages) CIRRUS

64 / 86 page

CS49300 Family DSP

DS339PP4

external ROM, in order to have access to the single

application code stored in the 32 kilobyte non-

paged memory. The host is completely isolated

from memory accesses in this situation. Once the

hardware has been designed, the DSP itself will be

responsible for all communication with the ROM.

8.7.2. 32 Kilobyte Paged Autoboot Memory

An external memory architecture which is paged

on 32 Kilobyte boundaries offers the higher end

system the ability to store several full download or

IBA application codes in each 32 Kilobyte page.

Figure 41 shows an example of a 32 Kilobyte

paged memory image for a the premium 6.1/7.1

channel system describe in Table 12 above.

The flow diagram given in Figure 36 demonstrates

the interaction required by the microcontroller

during autoboot. After placing the decoder into a

reset state, the host selects the page in memory

containing first code by driving uC15 to a low state.

The host also drives ABOOT low and holds it in a

low state until the rising edge of RESET to initiate

autoboot. As noted in the autoboot section, the

ABOOT pin should be connected to an open-drain

output of the microcontroller so as to allow the

specified pull-up resistor to generate the high

value. The open-drain driver is required because

the DSP will begin using the pin as an output after

a successful download (INTREQ and ABOOT are

multiplexed on the same pin).

After waiting for 175 ms, the download should

have completed. During the wait period, the host

should ignore all INTREQ behavior (mask the

INTREQ interrupt). The host can then verify that

the code has successfully initialized itself by

reading a variable from the application and

checking the returned value against the default

value. Any variable can be used for the verification

step, but a robust design will select a variable

whose value is neither all 0’s nor all 1’s. If the first

read attempt returns an incorrect value, a 5 ms wait

should be inserted and the read should be repeated.

If a second invalid number is read, the entire boot

process should be repeated. When the number

returned matches the default value for the variable

read, the host knows that the application is resident

in the DSP and awaiting further instruction. Please

see Section 8.2, “Autoboot” on page 56 for more

information.

For systems that would prefer to store all

application codes in an external parallel Flash

Memory (vs. a OTP EPROM) in order to realize a

“field-upgradable”

system,

please

contact

dsp_support@crystal.cirrus.com for information

Figure 40. Non-Paged Memory

0x00000

0x0FF F F

Dolby D igital with

P ro Logic II C ode

another F ull D ownload C ode

A dd ress line uC 15, uC 16, a nd

uC 17 us ed fo r paging

M P E G M ultichannel w ith

P ro Logic II

Dolb y Digital w ith

P ro Logic II w ith C irrus

E x tra S urround

0x00000

0x07F FF

0x08000

0x0F FF F

0x10000

0x17F FF

D T S -E S E xte nded S urrou nd

0x18000

0x1F FF F

D T S-ES N eo:6

0x20000

0x27F FF

HDCD

0x28000

0x2F FF F

LO G IC 7

0x30000

0x37F FF

MP 3

0x38000

0x3F FF F

V irtu al Dolby Dig ital w ith

V M A x V irtualT heater

Figure 41. Example Contents of a Paged 32 Kilobytes

External Memory (Total 256 Kilobytes)

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