SAM3X8C Atmel Corporation, SAM3X8C Datasheet - Page 72

• Manufacturer Part Number: SAM3X8C
• Manufacturer: Atmel Corporation

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72
SAM3X/A
SAM3X/A
Table 11-6.
Table 11-7.
A word access to the SRAM or peripheral bit-band alias regions map to a single bit in the SRAM
or peripheral bit-band region.
The following formula shows how the alias region maps onto the bit-band region:
where:
Figure 11-2
the SRAM bit-band region:
Address
range
0x20000000-
0x200FFFFF
0x22000000-
0x23FFFFFF
Address
range
0x40000000-
0x400FFFFF
0x42000000-
0x43FFFFFF
• accesses to the 32MB peripheral alias region map to the 1MB peripheral bit-band region, as
• Bit_word_offset is the position of the target bit in the bit-band memory region.
• Bit_word_addr is the address of the word in the alias memory region that maps to the
• Bit_band_base is the starting address of the alias region.
• Byte_offset is the number of the byte in the bit-band region that contains the targeted bit.
• Bit_number is the bit position, 0-7, of the targeted bit.
• The alias word at 0x23FFFFE0 maps to bit[0] of the bit-band byte at 0x200FFFFF:
• The alias word at 0x23FFFFFC maps to bit[7] of the bit-band byte at 0x200FFFFF:
• The alias word at 0x22000000 maps to bit[0] of the bit-band byte at 0x20000000:
• The alias word at 0x2200001C maps to bit[7] of the bit-band byte at 0x20000000:
shown in
targeted bit.
0x23FFFFE0 = 0x22000000 + (0xFFFFF*32) + (0*4).
0x23FFFFFC = 0x22000000 + (0xFFFFF*32) + (7*4).
0x22000000 = 0x22000000 + (0*32) + (0 *4).
0x2200001C = 0x22000000+ (0*32) + (7*4).
bit_word_offset = (byte_offset x 32) + (bit_number x 4)
bit_word_addr = bit_band_base + bit_word_offset
shows examples of bit-band mapping between the SRAM bit-band alias region and
Table
SRAM memory bit-banding regions
Peripheral memory bit-banding regions
Memory
region
SRAM bit-band
region
SRAM bit-band alias
Memory
region
Peripheral bit-band
alias
Peripheral bit-band
region
11-7.
Instruction and data accesses
Direct accesses to this memory range behave as SRAM
memory accesses, but this region is also bit addressable
through bit-band alias.
Data accesses to this region are remapped to bit band
region. A write operation is performed as read-modify-write.
Instruction accesses are not remapped.
Instruction and data accesses
Direct accesses to this memory range behave as peripheral
memory accesses, but this region is also bit addressable
through bit-band alias.
Data accesses to this region are remapped to bit band
region. A write operation is performed as read-modify-write.
Instruction accesses are not permitted.
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12