Programming, Protection, And Debug; Booting; Security Features; Safety Features - Analog Devices ADuCM356 Reference Manual

Reference Manual

PROGRAMMING, PROTECTION, AND DEBUG

BOOTING

The processor supports the following boot modes:
Booting from internal flash. Pin setting is 1.
►
If the BM/P1.1 pin = 0, user code is prevented from executing.
►
Control stays within the bootloader code with the serial wire
enabled. The user flash space cannot be viewed in this mode if
the space is protected by the user flash metadata.

SECURITY FEATURES

The ADuCM356 processor provides a combination of hardware and
software protection mechanisms that lock out access to the device
in secure mode but grant access in open mode. During startup,
the system is clocked from an internal on-chip oscillator. A reset
computes a hardware checksum of the information area and then
permits the CPU to execute the Analog Devices bootloader in the
flash information area if the checksum passes. The Analog Devices
bootloader inspects a GPIO boot pin, which determines whether
user code is allowed to execute or not.
The ADuCM356 features read protection, which protects device
contents (flash, SRAM, CPU registers, and peripheral registers)
from being read through an external interface by an unauthorized
user.

SAFETY FEATURES

The ADuCM356 processor provides a number of features that help
achieve certain levels of system safety and reliability. The level
of safety is mainly dominated by system considerations, and the
following safety features are provided to enhance robustness.
Multiparity Bit Protected L1 Memories
In the SRAM and cache L1 memory space, each word is protected
by multiple parity bits to detect the single event upsets that occur in
all RAMs.
Debug Features
The SWCLK and SWDIO pins are used for debugging and pro-
gramming. By default, an internal pull-up resistor to DVDD is pro-
vided. To save power, users can disable the internal pull-up resistor
and reconfigure these pins as tristate. Take care when reconfiguring
these pins from their default state, because this reconfiguration
disables debug access to the ADuCM356. It is recommended to
only disable the SWCLK and SWDIO feature of these pins in user
code when code development and debugging are almost complete.
If the SWCLK and SWDIO pins are accidently converted to tristate,
mass erase the device by resetting the device. Set BM/P1.1 = 0,
which allows the user to call the mass erase function of a serial
wire-based debugger.
The ADuCM356 can also utilize the analog die watchdog timer for
debugging. Disable the analog die watchdog timer when developing
or debugging user code. Enable the timer only toward the end
analog.com
of the development cycle. If left enabled during debug sessions,
unexpected watchdog timer resets can crash source level debugger
programs and cause unexpected resets to user sensor interface.
ADuCM356
Rev. A | 38 of 312