TX39_INTRENABLE2_REG
tx_conf_write(tc, TX39_INTRENABLE2_REG, 0);
iregs[2] = tx_conf_read(tc, TX39_INTRENABLE2_REG);
tx_conf_write(tc, TX39_INTRENABLE2_REG, 0);
tx_conf_write(tc, TX39_INTRENABLE2_REG, iregs[2]);