TX39_INTRENABLE5_REG
tx_conf_write(tc, TX39_INTRENABLE5_REG, 0);
iregs[5] = tx_conf_read(tc, TX39_INTRENABLE5_REG);
tx_conf_write(tc, TX39_INTRENABLE5_REG, 0);
tx_conf_write(tc, TX39_INTRENABLE5_REG, TX39_INTRSTATUS5_NEGONBUTNINT);
tx_conf_write(tc, TX39_INTRENABLE5_REG, iregs[5]);