SCA3000_REG_UNLOCK_ADDR
st->tx[0] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
st->tx[2] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
st->tx[4] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);