CS7666 Просмотр технического описания (PDF) - Cirrus Logic

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CS7666

Digital Color-Space Processor for CCD Cameras

Cirrus Logic 

CS7666

HIGH for READ packets. The master can read and

write to non-existent registers within the selected

device. WRITE operations will have no effect;

READ operations will return a value of 00h.

Station Address

Each device on the I2C bus has a unique 7-bit ad-

dress. An eighth bit, the R/W bit, determines if the

current data transfer writes data to the slave device

or reads data from the slave device. It is common to

represent the station address and R/W bit as two 8-

bit station addresses, one address for write accesses

and another address for read accesses. We will fol-

low this practice. The CS7666 default station ad-

dress is 34h for writes and 35h for reads. The

station address can be changed by writing a new

station address to register FFh. The value written to

this register does not include the R/W bit. For ex-

ample. The default station address (34h write / 35h

read) will be stored as 1Ah in register FFh.

Write Operations in Three-Byte Mode

The WRITE format consists of a three-byte packet.

The first byte is the station address with the data di-

rection bit set LOW to indicate a write. The second

byte is the device register address (0..255). The

third byte is the register data (0..255). No addition-

al bytes are allowed.

EPROM

CS7615

CS7666

CS4954

External

controller

To other sub-systems

Figure 7. I2C configuration showing primary

and secondary I2C busses.

Byte Sequence WRITE Format Packet Detail

First Byte

Station Address with LSB Set LOW

Second Byte Device Register Address (0..255)

Third Byte

Register Data (0..255)

Table 8. WRITE Format Packet

Address Set Operation

The ADDRESS SET format consists of a two-byte

packet which sets the address of a subsequent

READ operation. The first byte of the Station Ad-

dress with the LSB (data direction bit) set LOW to

indicate a write operation. The second byte is the

register address (0..255). The ADDRESS SET for-

mat is the same as the WRITE format, without the

register data (third byte).

Byte Sequence

ADDRESS SET format

Packet Details

First Byte

Station Address with LSB Set LOW

Second Byte Device Register Address (0..255)

Table 9. ADDRESS SET Format Packet Operation

Read Operations in Three-Byte Mode

The READ operation may consist of two or more

bytes. The first byte is the station address with the

LSB (data direction bit) set HIGH indicating a read

operation. The addressed device then sends one or

more bytes back from the register last addressed by

the previous WRITE operation or the previous AD-

DRESS SET operation.

Byte Sequence READ Format Packet Details

First Byte

Station Address with LSB set HIGH;

Source Device then Returns One

Byte of Register Data (0..255)

Second Byte Returned data from CS7666

Table 10. READ Format Packet.

Operating CS7666 in Four-Byte I2C Config-

uration

In this configuration the external controller talks

only to the CS7666 through the primary I2C inter-

face. All the other slave devices on the camera

DS302PP1

17

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