APPENDIX D BOOT
AP-D-4
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
USI_CK (SCPOL = 0, SCPHA = 0)
USI_DI/USI_DO
Fetching receive data
into shift register
8 bits
MSB
LSB
3.1.2 SPI Mode
Figure D.
SPI-EEPROM Boot Sequence
D.3.2
Figure D.3.2.1 shows the SPI-EEPROM boot flowchart.
START
Jumps to address 0x100
Configures USI (SPI master mode)
(SCPHA = 0, SCPOL = 0)
Configures SPI clock (PCLK1/16)
Issues RDSR command (0x05)
Issues READ command (0x03)
Configures the port functions
Switches #CE10 pin to P53 input
Initializes TTBR (0x20000000)
WIP bit
1
0
P53 (#CE10)
0
To PC RS232C
boot sequence
1
Loads 512-byte executable code
Issues 32-bit address
3.2.1 SPI-EEPROM Boot Flowchart
Figure D.
(1) When the BOOT and P53 (#CE10) pins are set to 1 at power-on or reset, the SPI-EEPROM boot sequence is
executed.
(2) The boot sequence configures the port and the USI module.
(3) Issues the RDSR (Read Status Register) command (0x05) to the EEPROM and reads the WIP (Write In Prog-
ress) bit to check the EEPROM status.
Waits for the EEPROM be ready status if it is busy.
(4) Issues the READ command (0x03) with a 32-bit address (0x00
×
4 bytes) to the EEPROM.