CY22394(2008) 查看數據表（PDF） - Cypress Semiconductor

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CY22394
(Rev.:2008)

Three-PLL Serial-Programmable Flash-Programmable Clock Generator

Cypress Semiconductor 

CY22393, CY22394, CY22395

Writing Multiple Bytes

To write multiple bytes at a time, the master must not end the

write sequence with a STOP condition. Instead, the master

sends multiple contiguous bytes of data to be stored. After each

byte, the slave responds with an acknowledge bit, the same as

after the first byte, and accepts data until the STOP condition

responds to the acknowledge bit. When receiving multiple bytes,

the CY22393, CY22394, and CY22395 internally increment the

register address.

Read Operations

Read operations are initiated the same way as Write operations

except that the R/W bit of the slave address is set to ‘1’ (HIGH).

There are three basic read operations: current address read,

random read, and sequential read.

Current Address Read

The CY22393, CY22394 and CY22395 have an onboard

address counter that retains “1” more than the address of the last

word access. If the last word written or read was word ‘n’, then a

current address read operation returns the value stored in

location ‘n+1’. When the CY22393, CY22394 and CY22395

receive the slave address with the R/W bit set to a ‘1’, they issue

an acknowledge and transmit the 8-bit word. The master device

does not acknowledge the transfer, but generates a STOP

condition, which causes the CY22393, CY22394 and CY22395

to stop transmission.

Random Read

Through random read operations, the master may access any

memory location. To perform this type of read operation, first set

the word address. Do this by sending the address to the

CY22393, CY22394 and CY22395 as part of a write operation.

After the word address is sent, the master generates a START

condition following the acknowledge. This terminates the write

operation before any data is stored in the address, but not before

setting the internal address pointer. Next, the master reissues

the control byte with the R/W byte set to ‘1’. The CY22393,

CY22394 and CY22395 then issue an acknowledge and transmit

the 8-bit word. The master device does not acknowledge the

transfer, but generates a STOP condition which causes the

CY22393, CY22394 and CY22395 to stop transmission.

Sequential Read

Sequential read operations follow the same process as random

reads except that the master issues an acknowledge instead of

a STOP condition after transmitting the first 8-bit data word. This

action increments the internal address pointer, and subsequently

outputs the next 8-bit data word. By continuing to issue acknowl-

edges instead of STOP conditions, the master serially reads the

entire contents of the slave device memory. Note that register

addresses outside of 08H to 1BH and 40H to 57H can be read

from but are not real registers and do not contain configuration

information. When the internal address pointer points to the FFH

register, after the next increment, the pointer points to the 00H

register.

Figure 2. Data Transfer Sequence on the Serial Bus

SCLK

SDAT

START

Condition

Address or

Acknowledge

Valid

Data may

be changed

STOP

Condition

Document #: 38-07186 Rev. *D

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