#include <DigiUSB.h>

#define RXD 0
#define TXD 1
#define CLK 2

#define WAIT 500

char no = 0;
uint8_t receive;

void setup()
{
  pinMode(TXD, OUTPUT);
  pinMode(RXD, INPUT);
  pinMode(CLK, OUTPUT); 
  digitalWrite(CLK, LOW);

  //ノイズ対策(?)のため7bit送る
  for(int i=0; i<7; i++)
  {
    digitalWrite(TXD, HIGH);
    delayMicroseconds(WAIT);
    digitalWrite(CLK, HIGH);
    delayMicroseconds(WAIT);
    digitalWrite(CLK, LOW);
  }

  DigiUSB.begin();
}

void loop()
{
  if(DigiUSB.available())
  {
    sendByte(DigiUSB.read());
  }
  DigiUSB.delay(10);
}

void sendByte(byte b)
{
  uint8_t onebit;

  receive = 0;
  
  for(int i=0; i<8; i++)
  {
    onebit = (b >> (7 - i)) & 1;
    digitalWrite(TXD, onebit);
    delayMicroseconds(WAIT);
    digitalWrite(CLK, HIGH);
    delayMicroseconds(WAIT);
    receive += (digitalRead(RXD) << (7 - i));
    digitalWrite(CLK, LOW);
  }
}