void set_ratio(unsigned int value)
{
  *PWM1TCR = 0; // PWMW[̓~߂
  *PWM1MR1 = (value < 1000) ? value : 1000;
  *PWM1TCR = *PWM1TCR | (1 << 0) | (1 << 3); // PWMW[̓ĊJ
}
