Mode Entry Module (MC_ME) RM0046
170/936 Doc ID 16912 Rev 5
ME_RESET_MC register. This mode has a pre-defined configuration, and the 16 MHz int.
RC osc. is selected as the system clock.
DRUN Mode
The device enters this mode on the following events:
● automatically from RESET mode after completion of the reset sequence
● from RUN0…3, SAFE, or TEST mode when the TARGET_MODE bit field of the
ME_MCTL register is written with “0011”
As soon as any of the above events has occurred, a DRUN mode transition request is
generated. The mode configuration information for this mode is provided by the
ME_DRUN_MC register. In this mode, the flashes, all clock sources, and the system clock
configuration can be controlled by software as required. After system reset, the software
execution starts with the default configuration selecting the 16 MHz int. RC osc. as the
system clock.
This mode is intended to be used by software
● to initialize all registers as per the system needs
Note: Software must ensure that the code executes from RAM before changing to this mode if the
flashes are configured to be in the low-power or power-down state in this mode.
SAFE Mode
The device enters this mode on the following events:
● from DRUN, RUN0…3, or TEST mode when the TARGET_MODE bit field of the
ME_MCTL register is written with “0010”
● from any mode except RESET due to a SAFE mode request generated by the
MC_RGM because of some potentially recoverable hardware failure in the system (see
the MC_RGM chapter for details)
As soon as any of the above events has occurred, a SAFE mode transition request is
generated. The mode configuration information for this mode is provided by the
ME_SAFE_MC register. This mode has a pre-defined configuration, and the 16 MHz int. RC
osc. is selected as the system clock.
If the SAFE mode is requested by software while some other mode transition process is
ongoing, the new target mode becomes the SAFE mode regardless of other pending
requests or new requests during the mode transition. No new mode request made during a
transition to the SAFE mode will cause an invalid mode interrupt.
Note: If software requests to change to the SAFE mode and then requests to change back to the
parent mode before the mode transition is completed, the device’s final mode after mode
transition will be the SAFE mode.
As long as a SAFE event is active, the system remains in the SAFE mode, and any software
mode request during this time is ignored and lost.
This mode is intended to be used by software
● to assess the severity of the cause of failure and then to either
– re-initialize the device via the DRUN mode, or
– completely reset the device via the RESET mode.
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