8 MCP23017 Small Chip PCB

#include <Adafruit_MCP23X17.h>

unsigned long current_time, previous_time = 0;
int i, j, state = 0;

Adafruit_MCP23X17 mcp[8];

void setup()
{
  for (j=0; j<8; j++)
  {
    mcp[j].begin_I2C(0x20+j);
    for (i=0; i<16; i++)
    {
      mcp[j].pinMode(i, OUTPUT);
    }
  }
}

void loop()
{
  for (j=0; j<8; j++)
  {
    for (i=0; i<16; i++)
    {
      state = 0;
      while (state != 2)
      {
        current_time = millis();
        if (current_time - previous_time >= 50)
        {
          previous_time = current_time;
          if (state == 0)
          {
            state = 1;
            mcp[j].digitalWrite (i, state);
          }
          else if (state == 1)
          {
            state = 0;
            mcp[j].digitalWrite (i, state);
            state = 2;
          }
        }
      }
    }
  }
}
//correct