JAJSVR9K December   2005  – December 2024 PCA9557

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 I2C Interface Timing Requirements
    7. 5.7 Reset Timing Requirements
    8. 5.8 Switching Characteristics
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Functional Block Diagram
    2. 7.2 Feature Description
      1. 7.2.1 RESET
        1. 7.2.1.1 RESET Errata
          1. 7.2.1.1.1 System Impact
          2. 7.2.1.1.2 System Workaround
      2. 7.2.2 Power-On Reset
    3. 7.3 Programming
      1. 7.3.1 I2C Interface
    4. 7.4 Register Maps
      1. 7.4.1 Device Address
      2. 7.4.2 Control Register And Command Byte
      3. 7.4.3 Register Descriptions
        1. 7.4.3.1 Bus Transactions
          1. 7.4.3.1.1 Writes
          2. 7.4.3.1.2 Reads
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Minimizing ICC when I/O is Used to Control LED
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Power-On Reset Errata
        1. 8.3.1.1 System Impact
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 サポート・リソース
    4. 9.4 Trademarks
    5. 9.5 静電気放電に関する注意事項
    6. 9.6 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4.2 Control Register And Command Byte

Following the successful acknowledgment of the address byte, the bus controller sends a command byte that is stored in the control register in the PCA9557. Two bits of this data byte state the operation (read or write) and the internal registers (input, output, polarity inversion or configuration) that is affected. This register is written or read through the I2C bus. The command byte is sent only during a write transmission.

Once a new command byte has been sent, the register that was addressed continues to be accessed by reads until a new command byte has been sent. Figure 7-8 shows the PCA9557 control register bits.

PCA9557 Control Register BitsFigure 7-8 Control Register Bits

Table 7-3 shows the PCA9557 command byte.

Table 7-3 Command Byte
CONTROL REGISTER BITSCOMMAND BYTE
(HEX)		REGISTERPROTOCOLPOWER-UP
DEFAULT
B1B0
000×00Input PortRead byte×××× ××××
010×01Output PortRead/write byte0000 0000
100×02Polarity InversionRead/write byte1111 0000
110×03ConfigurationRead/write byte1111 1111