I2CFIER
OUT32(id, I2CFIER, 0);
fier = IN32(id, I2CFIER);
OUT32(id, I2CFIER, 0);
OUT32(id, I2CFIER, fier);
OUT32(id, I2CFIER, 0);
OUT32(id, I2CFIER, FIER_RXIE);
OUT32(id, I2CFIER, FIER_TEIE | (id->msg->len ? FIER_TXIE : 0));
OUT32(id, I2CFIER, 0);
OUT32(id, I2CFIER, 0);