Embedded Sram - ST STM32G4 Series Reference Manual

A mapping formula shows how to reference each word in the alias region to a corresponding
bit in the bit-band region. The mapping formula is:
bit_word_addr = bit_band_base + (byte_offset x 32) + (bit_number × 4)
where:
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Example
The following example shows how to map bit 2 of the byte located at SRAM1 address
0x20000300 to the alias region:
0x22006008 = 0x22000000 + (0x300*32) + (2*4)
Writing to address 0x22006008 has the same effect as a read-modify-write operation on bit
2 of the byte at SRAM1 address 0x20000300.
Reading address 0x22006008 returns the value (0x01 or 0x00) of bit 2 of the byte at SRAM1
address 0x20000300 (0x01: bit set; 0x00: bit reset).
2.4

Embedded SRAM

The STM32G4 Series category 3 devices feature up to 128 Kbytes SRAM:
• 80 Kbytes SRAM1 (mapped at address 0x2000 0000)
• 16 Kbytes SRAM2 (mapped at address 0x2001 4000)
• 32 Kbytes CCM SRAM (mapped at address 0x1000 0000 and end of SRAM2)
The STM32G4 Series category 2 devices feature up to 32 Kbytes SRAM:
•
16 Kbytes SRAM1 (mapped at address 0x2000 0000)
•
6 Kbytes SRAM2 (mapped at address 0x2001 4000)
•
10 Kbytes CCM SRAM (mapped at address 0x1000 0000 and end of SRAM2)
These SRAM can be accessed as bytes, half-words (16 bits) or full words (32 bits). These
memories can be addressed at maximum system clock frequency without wait state and
thus by both CPU and DMA.
The CPU can access the SRAM1 through the system bus or through the ICode/DCode
buses when boot from SRAM1 is selected or when physical remap is selected
(Section 9.2.1: SYSCFG memory remap register (SYSCFG_MEMRMP)
controller). To get the maximum performance on SRAM1 execution, physical remap should
be selected (boot or software selection).
CCM SRAM is mapped at address 0x1000 0000.
Execution can be performed from CCM SRAM with maximum performance without any
remap thanks to access through ICode bus.
The CCM SRAM is aliased at address following the end of SRAM2 (0x2000 5800 for
category 2 devices, 0x2001 8000 for category 3 devices), offering a continuous address
space with the SRAM1 and SRAM2.
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bit_word_addr is the address of the word in the alias memory region that maps to
the targeted bit
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
RM0440 Rev 1
RM0440
in the SYSCFG