NO:
W90P710 Programming Guide
VERSION:
2.1
PAGE:
29
The above information is the exclusive intellectual property of Winbond Electronics and shall not be disclosed,
distributed or reproduced without permission from Winbond.
Table No.: 1200-0003-07-A
•
The EBI controller is select to the boot ROM was selected by EBI controller after reset.
•
The reset value of BASADDR of ROM/Flash control register is 0.
•
The default size of the boot ROM is 256Kb256KB.
•
The default value of tACC is the longest value. This value is supposed to suit support any kind of
ROM/Flash.
•
The boot ROM/Flash data bus width is determined by the data bus signals D [13: 12] in power-
on setting. The external hardware has the responsibility to weak needs to do the pull-up, or pull-
down setting on the D [13: 12] according to the boot ROM/Flash types.
•
PGMODE is set in normal ROM mode.
By the configurations shown above, the instruction fetch can be sure to be performed can be
fetched from the start of the boot ROM. However, if the boot ROM/Flash has more others functions, ex:
such as PGMODE, or more with larger size, the software has the responsibility to correct the setting
boot up program should configure the of ROM/Flash control register to let it work correctly after boot.
The ROM/Flash interface is designed for the boot ROM and it is supposed only to before read
operations. However, if a flash is attached to the ROM/Flash interface, it still can be written by the
writing programming command provided by of the flash. The ROM/Flash interface doesn’t hold the
writing command to the ROM/Flash. Thus the boot ROM/Flash is still programmable if the boot
ROM/Flash allows to be written. Thus, the attached Flash can be updated also by the programming
interface/sequence provided by the Flash.
2.4.3 SDRAM configuration registers
The SDRAM configuration registers enable software to set a number of operating parameters for
the SDRAM controller. There are two configuration registers SDCONF0, SDCONF1 for SDRAM bank 0,
bank 1 respectively. Each bank can have been set to different configurations. W90P710 also offers the
flexible timing control registers to control the generation and processing of the control signal and can
suit to control the timing of different speed type of SDRAMs. These timing control registers are
SDTIME0 and SDTIME1 for SDRAM bank 0, bank 1 respectively each.