9557 查看數據表（PDF） - NXP Semiconductors.

零件编号

产品描述 (功能)

生产厂家

9557

8-bit I2C-bus and SMBus I/O port with reset

NXP Semiconductors. 

NXP Semiconductors

PCA9557

8-bit I2C-bus and SMBus I/O port with reset

7. Functional description

Refer to Figure 1 “Block diagram of PCA9557”.

7.1 Device address

Following a START condition the bus master must output the address of the slave it is

accessing. The address of the PCA9557 is shown in Figure 8. To conserve power, no

internal pull-up resistors are incorporated on the hardware selectable address pins and

they must be pulled HIGH or LOW.

slave address

0 0 1 1 A2 A1 A0 R/W

fixed

Fig 8. PCA9557 device address

programmable

002aad279

The last bit of the slave address defines the operation to be performed. When set to

logic 1 a read is selected, while a logic 0 selects a write operation.

7.2 Control register

Following the successful acknowledgement of the slave address, the bus master will send

a byte to the PCA9557, which will be stored in the control register. This register can be

written and read via the I2C-bus.

bit: 7 6 5 4 3 2 1 0

0 0 0 0 0 0 D1 D0

002aad280

Fig 9. Control register

Table 4. Register definition

D1

D0

Name

0

0

Register 0

0

1

Register 1

1

0

Register 2

1

1

Register 3

Access

read-only

read/write

read/write

read/write

Description

Input port register

Output port register

Polarity inversion register

Configuration register

PCA9557

Product data sheet

Rev. 06 — 11 June 2008

© NXP B.V. 2008. All rights reserved.

7 of 26

Share Link: