Bit-Banding; Sram Memory Bit-Banding Regions; Peripheral Memory Bit-Banding Regions - Texas Instruments Concerto F28M35 Series Technical Reference Manual

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24.6.4 Bit-Banding

A bit-band region maps each word in a bit-band alias region to a single bit in the bit-band region. The bit-
band regions occupy the lowest 1 MB of the SRAM and peripheral memory regions. Accesses to the 32-
MB SRAM alias region map to the 1-MB SRAM bit-band region, as shown in
32-MB peripheral alias region map to the 1-MB peripheral bit-band region, as shown in
Note: A word access to the SRAM or the peripheral bit-band alias region maps to a single bit in the SRAM
or peripheral bit-band region.
A word access to a bit band address results in a word access to the underlying memory, and similarly for
halfword and byte accesses. This allows bit band accesses to match the access requirements of the
underlying peripheral.
Address Range
0x2000.0000 - 0x200F.FFFF
0x2200.0000 - 0x23FF.FFFF
Address Range
0x4000.0000 - 0x400F.FFFF
0x4200.0000 - 0x43FF.FFFF
The following formula shows how the alias region maps onto the bit-band region:
bit_word_offset = (byte_offset x 32) + (bit_number x 4)
bit_word_addr = bit_band_base + bit_word_offset
where:
bit_word_offset
The position of the target bit in the bit-band memory region.
bit_word_addr
The address of the word in the alias memory region that maps to the targeted bit.
bit_band_base
The starting address of the alias region.
byte_offset
The number of the byte in the bit-band region that contains the targeted bit.
bit_number
The bit position, 0-7, of the targeted bit.
Figure 24-12 shows examples of bit-band mapping between the SRAM bit-band alias region and the
SRAM bit-band region:
SPRUH22I – April 2012 – Revised November 2019
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Table 24-14. SRAM Memory Bit-Banding Regions
Memory Region
SRAM bit-band region
SRAM bit-band alias
Table 24-15. Peripheral Memory Bit-Banding Regions
Memory Region
Peripheral bit-band region
Peripheral bit-band alias
Copyright © 2012–2019, Texas Instruments Incorporated
Memory Regions, Types and Attributes
Table 24-14. Accesses to the
Table 24-15.
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.
Cortex-M3 Processor
1581