PORz release requires:
- All supplies have ramped to proper levels
- WKUP_HFOSC0 has a stable amplitude that propagates clocks into the core
PORz must be held active (low) for a minimum of 1.2 µs.
If PORz is asserted with MCU_PORz, then PORz propagates to the MAIN domain immediately.
If PORz is asserted independent of MCU_PORz, then the user code must have setup:
- CTRLMMR_WKUP_POR_RST_CTRL[0] POR_RST_ISO_DONE_Z
(high) in order to block the PORz from immediate
propagation and
- CTRLMMR_WKUP_MAIN_POR_TO_CTRL[2:0] TIMEOUT_PER in
order to configure the timeout, after which PORz
is unconditionally propagated to MAIN domain.
PORz sequence is:
- When PORz is asserted low, hardware in the WKUP/MCU domain recognizes the PORz and generates an interrupt to WKUP_DMSC0 and MCU. Reset hardware latches the PORz low level.
- User software is responsible for isolating
WKUP/MCU domain from the MAIN domain.
The details of the
isolation are application specific and are carried
out in software. Connections between the WKUP/MCU
domain and the MAIN domain include:
- LPSC_WKUPMCU2MAIN - LPSC4
(WKUP_PSC0)
- LPSC_MAIN2WKUPMCU - LPSC5
(WKUP_PSC0)
- Communications channel: MCSPI3 is connected as a
master to MCU_MCSPI1; MCSPI4 is directly connected
as a slave to MCU_MCSPI2.
- WKUP_GPIOMUX_INTRTR0
- MAIN2MCU_LVL_INTRTR0
- MAIN2MCU_PLS_INTRTR0
- WKUP_ESM0
- MCU_ESM0
When the
isolation is complete, MCU_R5FSS0 or WKUP_DMSC0
must write CTRLMMR_WKUP_POR_RST_CTRL[0]
POR_RST_ISO_DONE_Z low to allow the PORz signal to
propagate. - The release of PORz begins a read of eFuse values to register files; several different chains of e-fuse values are registered in parallel read sequences. Values are consumed by different blocks at various points in this sequence.
- PSC0 is initialized; specifically, PSC0 module configures default power states and LPSC (clocking) states.
- After power domain / clock domain initialization is completed, PSC modules release resets to the device (MOD_POR_RST, MOD_G_RST).
- CTRLMMR_WKUP_RST_STAT[0] MAIN_RST_DONE is
asserted.
At the end of this sequence, MCU_R5FSS can read
the CTRLMMR_WKUP_RST_STAT[0] MAIN_RST_DONE bit and
begin re-configuring the MAIN domain.