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SAA7121

Digital Video Encoder (ConDENC)

Philips Electronics 

Philips Semiconductors

Digital Video Encoder (ConDENC)

Preliminary specification

SAA7120; SAA7121

I2C-bus interface

The I2C-bus interface is a standard slave transceiver,

supporting 7-bit slave addresses and 400 kbits/s

guaranteed transfer rate. It uses 8-bit subaddressing with

an auto-increment function. All registers are write only,

except one readable status byte.

Two I2C-bus slave addresses are present:

88H: LOW at pin SA

8CH: HIGH at pin SA.

Tables 5 and 4 summarize the format of the I2C-bus

addressing. For more information on how to use the

I2C-bus see “The I2C-bus and how to use it”, order

no. 9398 393 40011. Tables 7 to 42 contain the

programming information for the subaddresses. Table 6

summarises this information.

Table 3 8-bit multiplexed format (similar to “CCIR 601”)

Sample

Luminance pixel number

Colour pixel number

0

Cb0

0

1

Y0

0

2

Cr0

1

BITS

2

4

Y1

Cb2

2

5

Y2

2

6

7

Cr2

Y3

3

Table 4 I2C-bus address format; see Table 5

S SLAVE ADDRESS ACK SUBADDRESS ACK DATA 0 ACK

--------

DATA n ACK P

Table 5 Explanation of Table 4

PART

S

Slave address

ACK

Subaddress(2)

DATA

--------

P

START condition

1 0 0 0 1 0 0 x or 1 0 0 0 1 1 0 x (1)

acknowledge, generated by the slave

subaddress byte

data byte

continued data bytes and ACKs

STOP condition

DESCRIPTION

Notes

1. x is the read/write control bit; write:

x = logic 0;

read: x = logic 1, no subaddressing with read.

2. If more than 1 byte DATA is transmitted, then auto-increment of the subaddress is performed.

1997 Jan 06

11

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