SCPS128D July   2006  – March 2021 PCA9554

PRODUCTION DATA  

  1. Features
  2. Description
  3. Revision History
  4. Description (Continued)
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Interface Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Functional Block Diagram
    2. 8.2 Device Functional Modes
      1. 8.2.1 Power-On Reset
      2. 8.2.2 I/O Port
      3. 8.2.3 Interrupt Output ( INT)
        1. 8.2.3.1 Interrupt Errata
          1.        23
          2. 8.2.3.1.1 24
          3. 8.2.3.1.2 25
    3. 8.3 Programming
      1. 8.3.1 I2C Interface
      2. 8.3.2 Register Map
        1. 8.3.2.1 Device Address
        2. 8.3.2.2 Control Register And Command Byte
        3. 8.3.2.3 Register Descriptions
        4. 8.3.2.4 Bus Transactions
          1. 8.3.2.4.1 Writes
          2. 8.3.2.4.2 Reads
  9. Application Information Disclaimer
    1. 9.1 Application Information
      1. 9.1.1 Typical Application
        1. 9.1.1.1 Design Requirements
          1. 9.1.1.1.1 Minimizing ICC When I/Os Control Leds
  10. 10Power Supply Recommendations
    1. 10.1 Power-On Reset Requirements
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Control Register And Command Byte

Following the successful acknowledgment of the address byte, the bus master sends a command byte that is stored in the control register in the PCA9554. Two bits of this command byte state the operation (read or write) and the internal register (input, output, polarity inversion or configuration) that will be affected. This register can be written or read through the I2C bus. The command byte is sent only during a write transmission.

Once a command byte has been sent, the register that was addressed continues to be accessed by readsuntil a new command byte has been sent.

GUID-2A6A8C69-3D6F-4431-B194-B5ABB9408FBB-low.gifFigure 8-7 Control Register Bits
Table 8-3 Command Byte
CONTROL REGISTER BITSCOMMAND BYTE
(HEX)
REGISTERPROTOCOLPOWER-UP
DEFAULT
B1B0
000x00Input Port RegisterRead byteXXXX XXXX
010x01Output Port RegisterRead/write byte1111 1111
100x02Polarity Inversion RegisterRead/write byte0000 0000
110x03Configuration RegisterRead/write byte1111 1111