ST STM32H757 User Manual

The Cortex-M4 processor PM0214
32/262 PM0214 Rev 10
2.2.5 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 Mbyte of the SRAM and peripheral
memory regions.
The memory map has two 32 Mbyte alias regions that map to two 1 Mbyte bit-band regions:
• Accesses to the 32 Mbyte SRAM alias region map to the 1 Mbyte SRAM bit-band
region, as shown in Table 14
• Accesses to the 32 MB peripheral alias region map to the 1 MB peripheral bit-band
region, as shown in Table 15.
Note: 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.
Bit band accesses can use byte, halfword, or word transfers. The bit band transfer size
matches the transfer size of the instruction making the bit band access.
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
Table 14. SRAM memory bit-banding regions
Address
range
Memory
region
Instruction and data accesses
0x20000000-
0x200FFFFF
SRAM bit-band region
Direct accesses to this memory range behave as SRAM memory
accesses, but this region is also bit addressable through bit-band alias.
0x22000000-
0x23FFFFFF
SRAM 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.
Table 15. Peripheral memory bit-banding regions
Address
range
Memory
region
Instruction and data accesses
0x40000000-
0x400FFFFF
Peripheral
bit-band region
Direct accesses to this memory range behave as peripheral memory
accesses, but this region is also bit addressable through bit-band
alias.
0x42000000-
0x43FFFFFF
Peripheral
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.

ST STM32H757 Specifications

General

Brand	ST
Model	STM32H757
Category	Computer Hardware
Language	English