The TMS320F28P55xMCU products have a
common architectural definition of operating states. These operating states must be observed
by the system developer in the software and system-level design concepts. The operating
states state machine is shown in Figure 4-9. The operating states can be classified into device boot phase and CPUSS operation phase.
The various states of the device operating states state machine are:
- Powered Off - This is the initial
operating state of the C2000 MCU. No power is applied to either core or I/O power supply
and the device is non-functional. An external supervisor can perform this action (power
down the C2000 MCU) in any of the C2000 MCU states in response to a system-level fault
condition or a fault condition indicated by the C2000 MCU.
- Reset State – In this state, the device
reset is asserted using either the external pins or using any of the internal
sources.
- Safe State – In the Safe state, the device is either not performing any functional operations or an internal fault condition is indicated using the device I/O pins.
- Cold Boot - In the cold boot state, the
CPU remains powered but in reset. When the cold boot process is completed, the reset of
the initiator CPU is internally released, leading to the warm boot stage.
- Warm Boot - The CPU begins execution from
boot ROM during the warm boot stage. CPU initializes the device security (all memories
come up as secure at the beginning of the warm boot and this stage configures the security
as needed for the particular system), exception handling and calibration of analog
components, and initializes the peripheral boot mode if required. For more details
regarding the boot process, see the device-specific boot ROM specification.
- Pre-operational - Transfer of control from
boot code to customer code takes place during this phase. Application-specific
configurations (for example, clock frequency, peripheral enable, pin mux, and so forth)
are performed in this phase. Boot time self-test and proof-test are required to verify
device operation is performed properly during this phase. See Section 6.4.3.20 (ROM8) for details.
- Operational – This marks the system
exiting the pre-operational state and entering the functional state. The device is capable
of supporting safety-critical functionality during operational mode.
The device start-up timeline for both CPUs are
shown in Figure 4-10.