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CXD2085M

ID-1 Detection

Sony Semiconductor 

CXD2085M

1. Description of ID-1 (transmission system of additional video information, aspect ratio identification)

As shown in the table below, the additional video information consists of 14-bits data, and a 6-bit CRCC is

added to the data to form 20-bit data in total. This is carried on lines 20 and 283 in the vertical blanking area of

the NTSC video signal.

Table 1. Description of ID-1 signal

A

WORD0

B

WORD1

WORD2

Bit No.

1

2

3

4

5

6

4bits

4bits

Description

Transmission aspect ratio

Screen display format

Not defined

"1"

Full-mode (16:9)

Letter-box

—

"0"

4:3

Normal

—

Identification information relating to the video signals and other signals (audio

signals, etc.) transmitted simultaneously with the video signals

Identification signal dependent on WORD0

Identification signal and other information dependent on WORD0

(From the Provisional standard of EIAJ, CPX-1204)

In the CXD2085M, the above 14-bit data are obtained in the I2C bus for I2C bus mode. Also, first two bits only

can be output to OLBX (Pin 15) and O169 (Pin 16) set as the direct output pins.

2. Difference between ID-1 Data from the I2C Bus and Direct Output Pin

14

ID-1 decoding

2

Direct pin outputs

OLBX, O169

Data validity determination

I2C

VBVLD

To microcomputer

CXD2085M

As shown in the figure above, the data validity determination which detects that the valid ID signal is exist or

not, and the decoded result are obtained independently during ID-1 decoding. These two results are output to

the direct output pins after taking their logical AND.

Processing inside the microcomputer which has acquired the information from the I2C bus is performed either

by simply outputting this data directly to the pins or by taking the logical AND as above.

In addition, performing the processing when the data validity determination (VBVLD) is "1" and the decoding

results bits 1 and 2 are "0" allows the video to be identified as 4:3 video.

3. General-Purpose I/O Port Function

In I2C bus mode, the CXD2085M can use two pins OLBX (Pin 15) and O169 (Pin 16) as the general-purpose

I/O ports. The three types of setting are available; both two pins for inputs, for outputs, and one for input and

another for output. While resetting by XRST (Pin 1) in I2C bus mode, two pins are set as the general-purpose

input ports. Perform the power-on reset by XRST when there is a possibility that the IC external circuit and the

OLBX and O169 signals could collide. Be sure to set the OLBX and O169 pins as the output pins when they

are not used.

–5–

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