ARK-5420 User Manual 54Please carefully read and study the below screenshots and source codes in blue.Please download programming specifications for the PCA955 NXP semiconductor.6.1 ARK-5420 Digital DIO DefinitionSee Section 2.3.6.6.2 Configuration SequenceARK-5420’s GPIO is realized through PCA9554 GPIO IC connected to ICH SMBUS.Therefore, the configuration and access to GPIO IC is completed by IO Spaceaccessing ICH SMBUS controller.Below is the diagram of ICH SMBUS IO Space:For ARK-5420, IO address of the above SMB_BASE is 0xF040.The detailed SMBUS IO control access code, please refer to Chapter 3.The corresponding SMBUS slave address of PCA9554 of GPIO 00 - GPIO 07 onARK-5420 is 0x40 (8bit address):GPIO 00 – GPIO 07: PCA9554 0x40 (IO0 – IO7)Below are pinouts for PCA9554:SMB_BASE + Offset Mnemonic Register Name Default Type00h HST_STS Host Status 00h R/WC, RO, R/WC(special)02h HST_CNT Host Control 00h R/W, WO R/W03h HST_CMD Host Command 00h R/W04h XMIT_SLVA Transmit SlaveAddress 00h R/W05h HST_D0 Host Data 0 00h R/W06h HST_D1 Host Data 1 00h R/WTable 6.1: Pin DescriptionSymbol Pin DescriptionDIP16, SO16,SSOP16, TSSOP16HVQFN16 SSOP20A0 1 15 6 address input 0A1 2 16 7 address input 1A2 3 1 9 address input 2IO0 4 2 10 input/output 0IO1 5 3 11 input/output 1IO2 6 4 12 input/output 2IO3 7 5 14 input/output 3VSS 8 6 15 supply groundIO4 9 7 16 input/output 4IO5 10 8 17 input/output 5IO6 11 9 19 input/output 6IO7 12 10 20 input/output 7INT 13 11 1 interrupt output (open-drain)