【RaspberryPiPico C/C++】I/OエキスパンダーMCP23017使い方

#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/i2c.h"

// I2C defines
#define I2C_PORT ( i2c1 )
#define I2C_SDA ( 6 )
#define I2C_SCL ( 7 )

enum MCP23017_BANK0_ADR
{
    ADR_IODIRA,
    ADR_IODIRB,
    ADR_IPOLA,
    ADR_IPOLB,
    ADR_GPINTENA,
    ADR_GPINTENB,
    ADR_DEFVALA,
    ADR_DEFVALB,
    ADR_INTCONA,
    ADR_INTCONB,
    ADR_IOCON,
    ADR_IOCON_,
    ADR_GPPUA,
    ADR_GPPUB,
    ADR_INTFA,
    ADR_INTFB,
    ADR_INTCAPA,
    ADR_INTCAPB,
    ADR_GPIOA,
    ADR_GPIOB,
    ADR_OLATA,
    ADR_OLATB,
    ADR_MAX
};

#define MCP23017_SADR   ( 0x20 ) //0x2X

#define INIT_CMD_MAX ( 3 )
const uint8_t MCP23017_INIT_CMD[ INIT_CMD_MAX ][ 2 ] =
{
    { ADR_IOCON , 0x00 }, // default
    { ADR_IODIRA, 0x00 }, // all out
    { ADR_GPIOA , 0x00 }, // all low
};

int main()
{
    stdio_init_all();

    // I2C Initialisation. Using it at 400Khz.
    i2c_init( I2C_PORT, 400*1000 );
    
    gpio_set_function( I2C_SDA, GPIO_FUNC_I2C );
    gpio_set_function( I2C_SCL, GPIO_FUNC_I2C );
    gpio_pull_up( I2C_SDA );
    gpio_pull_up( I2C_SCL );

    // 初期化
    {
        for ( uint8_t i = 0; i < INIT_CMD_MAX; i++ )
        {
            i2c_write_blocking( I2C_PORT, MCP23017_SADR, &MCP23017_INIT_CMD[ i ][ 0 ], 2, false );
        }
    }

    while ( 1 )
    {
        static uint8_t data = 0x01;
        uint8_t buf[ 2 ];
        buf[ 0 ] = ADR_GPIOA;
        buf[ 1 ] = data;
        i2c_write_blocking( I2C_PORT, MCP23017_SADR, &buf[ 0 ], 2, false );
        sleep_ms( 300 );
        data =  (uint8_t)( ( data * 2 ) % 0xFF );
    }

    return 0;
}