M54455EVB User’s Manual, Rev. 4
14
Freescale Semiconductor
Figure 5. MCF5445x Input Clock Selection Cut-Trace
4.5
SPI Flash
A 16 Mbit SPI flash is connected to the MCF5445
x
via the DSPI interface. This same SPI flash can be
used to store reset configuration parameters and boot code when using the serial boot facility. Refer to
Section 4.3, “MCF5445x Boot Options
” for more information on how to configure the M54455EVB for
serial boot.
4.6
Flash
The M54455EVB features two flash devices connected to the FlexBus expansion bus. The smaller of the
two flashes is a 512KByte, 8-bit wide AT49BV040 (or compatible) device referred to as Flash0. This
device contains the U-Boot bootloader. The larger of the two flashes is a 16 MByte, 8-bit wide 28F128J3D
(or compatible) device referred to as Flash1. By default, this flash device is programmed with a Linux
image, but it can be reprogrammed and used as a boot device if desired.
The selection of a boot flash device is achieved with a CPLD mode switch setting, specifically
CPLD_MODE2 which is controllable by DIP switch SW1[3]. The device that is connected to the global
chip-select from the MCF5445
x
(FB_CS0) is the boot device. The other device is connected to FB_CS1.
shows the boot device selection settings.
Table 7. Flash Chip Select Configuration
SW1[3]
Meaning
Application
OFF
Flash1 is the boot device
FLASH1_CS = FB_CS0
FLASH0_CS = FB_CS1
Boot custom image
ON
Flash0 is the boot device
FLASH1_CS = FB_CS1
FLASH0_CS = FB_CS0
Boot U-Boot
cut trace
solder