CHAPTER 6 BUS CONTROL
User’s Manual U14272EJ3V0UM
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6.3 ROM Interface
The V
R
4181 supports three ROM modes, ordinary ROM, PageROM, and flash memory. The mode setting is made
via the BCUCNTREG1 register’s Rtype(1:0) bits and ROMWEN0 bit. Access speed setting in ordinary ROM or
PageROM mode is made via the BCUSPEEDREG register.
Remark
The V
R
4181 supports only 16-bit access for external ROM devices.
6.3.1 External ROM devices memory mapping
Physical address
32 Mbit ROM
64 Mbit ROM
0x1FFF FFFF to 0x1FC0 0000
Bank 3 (ROMCS3#)
Bank 3 (ROMCS3#)
0x1FBF FFFF to 0x1F80 0000
Bank 2 (ROMCS2#)
0x1F7F FFFF to 0x1F40 0000
Bank 1 (ROMCS1#)
Bank 2 (ROMCS2#)
0x1F3F FFFF to 0x1F00 0000
Bank 0 (ROMCS0#)
0x1EFF FFFF to 0x1E80 0000
Reserved
Bank 1 (ROMCS1#)
0x1E7F FFFF to 0x1E00 0000
Reserved
Bank 0 (ROMCS0#)
Bank 3 contains boot vector and has a dedicated pin for chip select (ROMCS3#). Chip select pins for Bank 2, 1,
and 0, ROMCS(2:0)#, are alternated with general-purpose I/O signals and are defined as general-purpose inputs
after RTC reset. Set GPMD2REG and GPMD3REG registers in the GIU to use them as ROMCS(2:0)#.