The C2000 MCU products have a common architectural definition of operating states. These operating states should be observed by the system developer in their 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 CPU Subsystem (CPUSS) operation phase.
The various states of the device operating states state machine are:
- Powered Off - This is the initial operating state of TMS320F28004x 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 TMS320F28004x MCU) in any of the TMS320F28004x MCU states as response to a system level fault condition or a fault condition indicated by the TMS320F28004x MCU.
- Reset State – In this state, the device reset is asserted either using 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, key analog elements, digital control logic, and debug logic are initialized. The CPU remains powered but in reset. When the cold boot process is completed, the reset of the CPU is internally released, leading to the warm boot stage.
- Warm Boot - The CPU begins execution from Boot ROM during the warm boot stage.
- 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, pinmux, and so
forth) are performed in this phase. Boot time self-test/proof-test required to
ensure proper device operation is performed during this phase. For details, see
ROM8-Power-Up Pre-Operational Security.
- 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 the CPUs are shown in Figure 4-10.