Figure 3-21 shows the sleep and wake-up transitions reset sequence from the RETENTION state of the MPU subsystem.
The assumption is:
- The DPLL_MPU is locked and is providing the clock to the MPU subsystem.
The sleep and wake-up transitions reset sequence is:
- The PRCM module gates MPU_DPLL_CLK to the MPU subsystem.
- The PRCM module switches PD_MPU to OSWR state.
- The PRCM module asserts MPU_PWRON_RST and MPU_RST resets to the MPU subsystem, and asserts MPU_MA_RST to the MA_MPU module. The entire logic in the PD_MPU is held in reset. The reset to the L2 cache memory in the MPU subsystem is not asserted if the logic in PD_MPU is held in reset.
- The PRCM module resets the L2 cache memory in the MPU subsystem by asserting its reset.
- The PRCM module releases MPU_RST when the MPU_DPLL_CLK is stable and active. The PRCM deasserts the MPU_PWRON_RST, MPU_MA_RST. When PRCM receives active MPU_RSTDONE signal from MPU, it de-asserts MPU_RST.
- During the wakeup from RET state, the MPU_L2RSTDISABLE signal must be maintained at active high so the L2 cache will not be reset when the MPU is reset.