ADuCM310 Hardware Reference Manual
UG-549
Rev. C | Page 65 of 192
RESET
RESET FEATURES
There are four following kinds of resets:
•
External reset
•
Power-on reset
•
Watchdog timeout
•
Software system reset
RESET OPERATION
The software system reset is provided as part of the Cortex-M3 processor. To generate a software system reset, the NVIC_SystemReset()
function must be called. This effectively writes 0x05FA to the top 16 bits of an AIRCR NVIC register. This function along with other
useful functions are defined in the CMSIS header files that are shipped with the tools from third party vendors. The NVIC_SystemReset()
function is defined in the
core_cm3.h
file.
The analog peripherals have the option of maintaining their state after a software or watchdog reset. This function is disabled by default.
It can be enabled using the LVRST register. Note that while debugging, the software tools generally only issue a software reset, meaning an
external reset is needed to return registers to their default values if the retain functionality is enabled.
The GPIO pins and PLA also have the option of maintaining their state after a software or watchdog reset. By default, this function is
disabled. Writing a value of 0x0 to RSTCFG configures the GPIO pins and PLA maintain their state after a software or watchdog reset.
Before writing to this register, 0x2009 must be written to RSTKEY followed by 0x0426. After the two keys are written to RSTKEY,
RSTCFG must be immediately written.
The RSTSTA register stores the cause for the reset until it is cleared by writing the RSTSTA register. RSTSTA can be used during a reset
exception service routine to identify the source of the reset.
The watchdog timer is enabled by default after a reset. The default timeout period is approximately 32 seconds.
User code must disable the watchdog timer at the start of user code when debugging or if the watchdog timer is not required.
pADI_WDT->T3CON = 0x00 ;
// Disable watchdog timer
Table 74. Device Reset Implications
Reset
Impact
Reset External Pins
to Default State
Execute Kernel
Reset All MMRs
Except RSTSTA
Reset All
Peripherals
Valid SRAM
RSTSTA After
Reset Event
Software Reset
Yes/No
Yes
Yes/No
Yes/No
Yes/No
RSTSTA[3] = 1
Watchdog Timeout
Yes/No
Yes
Yes/No
Yes/No
Yes/No
RSTSTA[2] = 1
External Reset Pin
Yes
Yes
Yes
Yes
Yes/No
RSTSTA[1] = 1
POR
Yes
Yes
Yes
Yes
No
RSTSTA[0] = 1
1
GPIO pins, PLA, and analog peripherals have the option of retaining their state during a watchdog or software reset.
2
RAM is not valid in the case of a reset following a UART download.
REGISTER SUMMARY: RESET
Table 75. Reset Register Summary
Address
Name
Description
Reset
Access
0x40002408
RSTCFG
Reset configuration
0x0000
RW
0x4000240C
RSTKEY
Key protection for RSTCFG
0x0000
RW
0x40002440
RSTSTA
Reset status
0x0000
RW
0x40082C34
LVRST
Low voltage die reset configuration
0x0000
RW