The System Mode Management (SMM) functional block describes the device system modes and transitions between them. SMM co-ordinates supply ramp-up, reset, start-up, operation, and ramp-down or standby states.

The LVD resets, Power Domain Cold Reset, Cold PORST Reset, LBIST Reset, warm PORST Reset, System Reset, and Application Reset are hierarchical in nature with the higher reset triggering the lower reset class. The Module Group Resets and module resets are exceptions to this general rule.

The PMS.PORDET detectors release the low voltage detector resets once adequate supply voltage levels are reached for isolation release, ensuring the start of the basic infrastructure and power supplies.

Once the supply system, internal clock and reference voltages are up and running, the primary voltage monitors PMS.VMONPx release the cold PORST ensuring that all internal and external supply voltages are above their minimum operational level. The LBIST would manifest externally as a device being in reset state but the device having high power consumption and load transients. The PORST pin is externally asserted or de-asserted by the external power supply to reset the microcontroller. The release of PORST activates CPU0 and CPUcs into RUN mode and starts the start-up software, and consequently the user application.

System and application resets are triggered by software and hardware sources to debounce errors and failures of parts of the microcontroller. The choice of reset depends on the time available for reset, the reset trigger, and the application needs. The SMM collects the triggers from various reset sources and issues warm reset (warm PORST, system, or application resets). All resets are propagated to external devices using ESRx, FSPx, and PORST pins.

Figure 1. SMM block diagram