APPENDIX D BOOT
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
AP-D-1
Appendix D Boot
Boot Mode
D.1
The S1C33L26 supports the three boot modes listed below.
• NOR Flash/external ROM boot
(Either 8 bits or 16 bits)
• SPI-EEPROM boot
• PC RS232C boot
The S1C33L26 boots up in the boot mode that can be selected with the BOOT and #CE10 pin configuration at ini-
tial reset.
1.1 Boot Mode Setting
Table D.
BOOT pin
#CE10 pin
Boot mode
Program execution start address
0
Output
NOR Flash/external ROM
The system starts executing from the address written at
address 0x20000000.
1
1 (Input)
SPI-EEPROM
The system loads MBR to IRAM (from address 0x100) and
starts executing the code loaded.
0 (Input)
PC RS232C
Note: The #CE10 pin includes a pull-up resistor and it is enabled at initial reset. Note, however, that the
#CE10 pin is configured as an input pin and its pull-up resistor is disabled in the initial process by
the boot sequencer when the BOOT pin is set to 1. Therefore, connect an external pull-up or pull-
down resistor to set the #CE10 pin input level to 1 or 0.
NOR Flash/External ROM Boot
D.2
Configuration of NOR Flash/External ROM Boot System
D.2.1
When the S1C33L26 is turned on or reset with the BOOT pin set to 0 (V
SS
), the S1C33L26 reads the reset vector
from address 0x20000000 in the external NOR Flash or external ROM and jumps to the user reset handler routine.
This boot sequence is similar to the standard function of the C33 PE Core. However, the S1C33L26 supports boot-
ing from an 8-bit NOR Flash in contrast to the C33 PE Core that supports only a 16-bit device. The S1C33L26
reads the reset vector using the internal boot sequencer, and configures the #CE10 device size to 8 or 16 bits ac-
cording to the LSB of the reset vector that is ignored in 16-bit boot. Then it jumps to the reset handler routine.
Figure D.2.1.1 shows a NOR Flash/external ROM boot system connection diagram.
#CE10
A[25:1]
D[15:0]
#RD
#WRL
#CE10
A[25:0]
D[15:0]
#RD
#WRL
BOOT
BOOT
S1C33L26
8-bit NOR Flash
(External ROM)
(1) 8-bit NOR Flash/External ROM
#CE
A[25:0]
DQ[7:0]
#OE
#WE
S1C33L26
16-bit NOR Flash
(External ROM)
(2) 16-bit NOR Flash/External ROM
#CE
A[24:0]
DQ[15:0]
#OE
#WE
2.1.1 NOR Flash/External ROM Boot System
Figure D.
This system uses only the external bus signals for #CE10 that are configured by default.