ST STM32F301 6 Series Reference Manual page 47

RM0366
Flash area
Flash memory
interface registers
1. The gray color is used for reserved Flash memory addresses.
The information block is divided into two parts:
•
System memory is used to boot the device in the System memory boot mode. The area
is reserved for use by STMicroelectronics and contains the bootloader, which is used to
reprogram the flash memory through one of the following interfaces: USART1,
USART2, or on devices with internal regulator ON and USART, I2C or SPI on devices
with internal regulator OFF. It is programmed by STMicroelectronics when the device is
manufactured, and protected against spurious write/erase operations. For further
details, refer to the AN2606 available from www.st.com.
•
Option bytes
3.2.2 Read operations
The embedded flash module can be addressed directly, as a common memory space. Any
data read operation accesses the content of the flash module through dedicated read
senses and provides the requested data.
The read interface consists of a read controller on one side to access the flash memory and
an AHB interface on the other side to interface with the CPU. The main task of the read
interface is to generate the control signals to read from the flash memory and to prefetch the
blocks required by the CPU. The prefetch block is only used for instruction fetches over the
ICode bus. The Literal pool is accessed over the DCode bus. Since these two buses have
the same flash memory as target, DCode bus accesses have priority over prefetch
accesses.
Read accesses can be performed with the following options managed through the Flash
access control register (FLASH_ACR):
•
Instruction fetch: Prefetch buffer enabled for a faster CPU execution.
•
Latency: number of wait states for a correct read operation (from 0 to 2)
Instruction fetch
The Cortex
(constant/data) over the DCode bus. The prefetch block aims at increasing the efficiency of
ICode bus accesses.
Table 3. Flash module organization
Flash memory addresses
0x4002 2000 - 0x4002 2003
0x4002 2004 - 0x4002 2007
0x4002 2008 - 0x4002 200B
0x4002 200C - 0x4002 200F
0x4002 2010 - 0x4002 2013
0x4002 2014 - 0x4002 2017
0x4002 2018 - 0x4002 201B
0x4002 201C - 0x4002 201F
0x4002 2020 - 0x4002 2023
®
-M4 fetches the instruction over the ICode bus and the literal pool
RM0366 Rev 5
Embedded flash memory
(1)
(continued)
Size
Name
(bytes)
4 FLASH_ACR
4 FLASH_KEYR
4 FLASH_OPTKEYR
4 FLASH_SR
4 FLASH_CR
4 FLASH_AR
4 Reserved
4 FLASH_OBR
4 FLASH_WRPR
47/874
67