Hi @jacqueshsu,
As you can see in the RM, Table 7-8. AWIC stop and VLPS wake-up sources, you can use the LPIT timer.
LPIT is functional in VLPS if the function clock of this module is SIRC and LPIT_MCR[DOZE_EN] = 1.
The SIRC clock must be enabled in VLPS (SCG_SIRCCSR[SIRCSTEN = 1, SIRCLPEN = 1).
BR, Daniel