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ZR36057

ENHANCED PCI BUS MULTIMEDIA CONTROLLER

Zoran Corporation 

Enhanced PCI Bus Multimedia Controller

5.5.4 Connecting The ZR36057 To The ZR36050

Figure 8 shows the recommended connection of the ZR36057 to

the ZR36050.

ZR36050

CLK_IN

CCS

CBUSY

END

CODE[7:0]

ZR36057

VCLKx2

CCS

CBUSY

CEND

CODE[7:0]

ADDR[9:0]

DATA[7:0]

n+1

CS

RD

WR

RESET

GADD

GDAT[7:0]

GCSn

GRD

GWR

GPIOn

Figure 8. ZR36057 to ZR36050 Connections

5.5.4.1 ZR36050 Host Interface

The host interface of the ZR36050 is controlled by the ZR36057

as one of the guests. The recommended guest timing parame-

ters are Tdur=12, Trec=3. An external register must be added in

order to support access to the entire ZR36050 internal memory

space. This external register is controlled by the ZR36057 as an

additional guest.

One basic host access to the ZR36050 internal memory via the

ZR36057 is performed using two successive guest bus access-

es. The first is to the external address register during which the

GDAT bus holds (for example) the 8 Lsb’s of the ZR36050

internal memory address. The second is the command itself

during which the GDAT bus holds the data to be written to the

ZR36050 internal memory and the 2 Msb’s of the address are

driven by GADD[1..0].

5.5.4.2 CEND Input Signal

Assertion of END by the ZR36050 indicates the end of a field

process in compression or decompression. This is latched as

CEND in the Codec Interface.

5.5.4.3 The ZR36050 GO Command

The GO command signals the ZR36050 to start a compression

or decompression process. The GO command is performed

automatically by the ZR36057, by writing to address 0x00h of

the ZR36050 internal memory. The host software is responsible

for pre-loading this address to the external address register after

the completion of ZR36050 initialization.

The ZR36057 uses the JPEGuestID and the JPEGuestReg

parameters for the GO command guest address.

In Motion Video Compression mode, the first GO command is

initiated by the host after finishing the initialization of all the

peripheral devices. After the first field, the GO command is

executed after the code of the previous field has been trans-

ferred to the system memory.

In Decompression mode, the GO command is executed only

after the Code FIFO has been filled from the relevant system

memory code buffer.

Important Note:

The automatic GO command is enabled by the Go_En register

bit, in the JPEG Mode and Control Register. If the host software

tries to execute a PostOffice cycle while Go_En is set to ‘1’

(enabled), the PostOffice cycle may not be executed correctly.

Therefore, Go_En must be disabled during PostOffice accesses.

The following is the sequence of actions required for a Post

Office access or series of accesses:

• Disable the Go_En bit.

• Wait at least 15 PCI clock cycles to allow the currently exe-

cuting GO command, if there is one, to be completed.

• Execute the PostOffice access, or the series of accesses.

• Enable the Go_En bit (at least for 5 PCI clocks).

If an internal GO command is requested while Go_En is dis-

abled, it is stored internally, and executed when Go_En is

enabled again.

Note that there is a trade-off between the “chunk” size of a series

of PostOffice accesses and the delay imposed on the ZR36050

GO command. Using a large chunk size reduces the overhead

resulting from the need to toggle Go_En, but delaying the GO

command too much can prevent the next field process from exe-

cuting correctly.

5.5.4.4 CCS Input Signal

The ZR36050 CCS signal designates the start of a code trans-

action. It stays active until the end of the transaction. In

Compression mode, the ZR36057 uses CCS to enable the

sampling of the incoming code stream. In Decompression mode,

it uses CCS to enable the drive of the code stream.

5.6 I2C Bus Interface

The I2C port of the ZR36057 consists of a clock signal, SCK, and

data signal, SDA. Both have two possible levels: active low or

passive tri-state. This configuration lets the ZR36057 be the only

master of an I2C clock. Both lines must be pulled-up externally.

By accessing the I2C application-specific register bits appropri-

ately, the host software can generate valid I2C start and stop

conditions, write address and write or read data one bit at a time.

5.7 General Purpose I/O Pins

The ZR36057 has 8 general purpose I/O pins, fully controlled by

the host. Each of these pins can be separately configured as

17

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