5 RESET AND NMI
5-2
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Initial Reset Sequence
5.1.3
Even if the #RESET pin input negates the reset signal after power is turned on, the CPU cannot boot up until the
oscillation stabilization waiting time (128 / OSC3 clock frequency) has elapsed.
Figure 5.1.3.1 shows the operating sequence following cancellation of initial reset.
The CPU starts operating in synchronization with the OSC3 clock after reset state is canceled.
Note: The oscillation stabilization time described in this section does not include oscillation start time.
Therefore the time interval until the CPU starts executing instructions after power is turned on or
SLEEP mode is canceled may be longer than that indicated in the figure below.
Boot vector
Oscillation stabilization
waiting time
Booting
OSC3 clock
#RESET
Internal reset
Internal data request
Internal data address
Internal reset canceled
Reset canceled
1.3.1 Operation Sequence Following Cancellation of Initial Reset
Figure 5.
Initial Reset Status
5.1.4
The C33 PE Core and internal peripheral circuits are initialized while the internal reset signal is at kept 0. The fol-
lowing shows the reset status of the internal IC with the initial reset.
1.4.1 Initial Reset Status
Table 5.
Item
Boot mode
Initial reset status
CPU - TTBR
NOR Flash/
external ROM boot
Initialized to 0x20000000
SPI-EEPROM boot
PC RS232C boot
ICD debug
Initialized to 0x20000
CPU - PC
NOR Flash/
external ROM boot
The reset vector at address 0x20000000 is loaded to the PC.
SPI-EEPROM boot 0x100 is loaded to the PC
PC RS232C boot
ICD debug
0x20000 is loaded to the PC
CPU - PSR
–
Undefined
CPU - Other registers
–
Undefined
CPU - Operating clock
–
The CPU operates with OSC3
×
1/1 clock.
Oscillator circuits
–
Both the high-speed (OSC3) and low-speed (OSC1) oscillator circuits
are turned on. (PLL and SSCG are turned off.)
Clock supply to
peripheral modules
–
Clocks are supplied to all the peripheral modules except LCDC and
USB.
I/O pin state
–
I/O pins are initialized.
(See the “Pin Functions” section in the “Overview” chapter.)
Other internal peripheral
circuits
–
Initialized or undefined (See each I/O map.)
Note: The S1C33L26 does not support a hot reset feature that maintains I/O pin status and the TTBR
value.