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Chapter 26
Reset
Preliminary User’s Manual U17566EE1V2UM00
(3)
Register status
With each reset function the registers of the CPU, internal RAM, and on-chip
peripheral I/Os are initialized.
Since after reset the internal firmware is processed, some resources hold a
different value as after reset, when the user’s program is started. After a reset,
make sure to set the registers to the values needed within your program.
Table 26-2
Initial values of CPU and internal RAM after reset
On-chip hardware
Register name
Initial value
After Reset
At start of user’s program
CPU
Program
registers
General-purpose register (r0)
0000 0000
H
0000 0000
H
General-purpose registers
(r1 to r31)
Undefined
Undefined
Program counter (PC)
0000 0000
H
Variable reset vector
programmed to flash extra area
System
registers
Status save registers during interrupt
(EIPC, EIPSW)
Undefined
Undefined
Status save registers during non-
maskable interrupt (NMI)
(FEPC, FEPSW)
Undefined
Undefined
Interrupt cause register (ECR)
0000 0000
H
0000 0000
H
Program status word (PSW)
0000 0020
H
•
0000 0020
H
: if no security
flags or variable reset vector
are set
•
0000 0021
H
: else
Status save registers during CALLT
execution (CTPC, CTPSW)
Undefined
Undefined
Status save registers during
exception/debug trap (DBPC,
DBPSW)
Undefined
Undefined
CALLT base pointer (CTBP)
Undefined
Undefined
Internal RAM After
power-on
After Power-On-Clear reset the
entire RAM contents is undefined.
Undefined
Undefined
After
RESET
If a RESET occurs while writing to a
RAM memory block, the contents of
that RAM memory block may be
corrupted. All other RAM memory
blocks are not affected.
Refer also to the note below the
table.
All data in
previous
state
• 03FF 0000
H
- 03FF 07FF
H
:
undefined
All other data in previous state
or undefined (refer to note
below).
After any
other
reset
Any internal generated reset does
not change the RAM contents.
All data in
previous
state
• 03FF 0000
H
- 03FF 07FF
H
:
undefined
All other data in previous state.
Peripherals
Macro internal registers
The reset values of the various registers are
given in the chapters of the peripheral
functions
electronic components distributor