Mode Entry Module; System Status And Configuration Module; Reset Sequence - STMicroelectronics SPC572L series Reference Manual

RM0400
normally and the state of analog modules, specific digital modules (e.g., debug and flash
memory modules) and system memory content is preserved.
Examples of functional resets are:
•
External reset.
•
Machine check.
•
Software reset from mode entry.
•
Boundary scan instructions.
7.2.3

Mode Entry module

The Mode Entry module (MC_ME) is responsible for delivering initial values to many
registers, including the reset vectors to the SPC572Lx core.
During the power-up sequence, the System Status and Configuration Module (SSCM)
searches for a boot header at defined locations in the flash memory, derives the necessary
reset vectors from the boot header and then writes these vectors to their respective
locations in the Mode Entry module.
The SSCM also interprets the DCF records which contain further information that is written
to the MC_ME. As the boot-up sequence progresses, the SSCM instructs the MC_ME to
transfer the reset vectors to the core.
Even though the reset vectors are in the boot header located in flash memory, the Mode
Entry module always provides them to the CPU cores.
7.2.4

System Status and Configuration Module

During the reset sequence, the Reset Generation Module (MC_RGM) enables the SSCM
state machine which reads the DCF records in the TEST and UTEST flash memory areas
for device setup information to be written to various registers in the SPC572Lx.
The DCF records are primarily for setting up the memory and providing initial device
configuration values.
The SSCM continues with the reset or boot-up sequence by locating boot vectors for the
core. Once the SSCM locates the boot header, the SSCM writes the start address
information for the CPU core to special locations in the Mode Entry Module (MC_ME). The
MC_ME feeds a reset vector to the core which begins program execution at the specified
address.
The boot-up sequence ends when the SSCM starts up the CPU.
7.3

Reset sequence

The power-up reset sequence always begins with the application of power and follows
different sequences depending on the condition of the SPC572Lx device and whether
various modes are enabled from settings in the DCF records. For instance, the SPC572Lx
device enters Serial Boot mode (the Serial Boot Loader receives startup code and begins
program execution) if a valid boot header file is not found.
Another reset outcome is that the CPU is properly started and begins executing program
code.
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