ARM Cortex-M3 主频可至64MHz
256 Kbytes 内置 Flash
48 Kbytes 静态 SRAM
The SRAM is accessible over System Cortex-M3 bus at address 0x2000 0000
16 Kbytes ROM( UART, USB驱动和在线应用升级IAP)
调试器开发支持：
1. Serial Wire/JTAG Debug Port(SWJ-DP)
Serial Wire Debug Port (SW-DP) and Serial Wire JTAG Debug Port (SWJ-DP) debug access.
- 访问所有的内存和系统的寄存器
当内核处于 运行，挂起，或者 reset暂停 状态时，寄存器都可以访问 - Flash Patch and Breakpoint (FPB) unit for implementing breakpoints and code patches.
- Data Watchpoint and Trace (DWT) unit for implementing watchpoints, data tracing, and system profiling.
- Instrumentation Trace Macrocell (ITM) for support of printf style debugging.
- IEEE1149.1 JTAG Boundary-scan on all digital pins.
在SRAM中执行代码
- 实现升级程序时， 此时Flash被擦除或者写入，不能执行代码
- 调试功能是，代码下载到SRAM中更快，且不会频繁写FLASH,造成Flash过快损耗。
https://community.arm.com/developer/tools-software/tools/f/armds-forum/992/cortex-m3-execution-code-from-ram-during-flash-programming/2971
https://community.arm.com/developer/tools-software/tools/f/keil-forum/30830/executing-code-from-sram
https://community.arm.com/developer/tools-software/tools/f/keil-forum/31659/no-jlink-algorithm-for-cortex-sram
使用keil的LOAD命令
http://www.keil.com/support/man/docs/uv4/uv4_cm_load.htm
https://stackoverflow.com/questions/42612329/executing-code-from-ram-in-stm32
https://studio.segger.com/index.htm?https://studio.segger.com/ide_section_placement.htm
These are the steps needed to get the whole application placed in RAM, and to get it to run as expected in RAM.
Get data (read/write and constant) and code linked to be placed in RAM.
Place the Vector Table in RAM (with at least the alignment forced by the Cortex-M design.)
During C-start-up, set VTOR to the address of the Vector Table.
两种方法
Place CODE and DATA in RAM.
Use the “edit”-button (or change directory in your .icf file) at Project > Options > Linker > Config to open the window “Linker configuration file editor”
配置链接器
Go to the tab “memory regions” – copy the value in RAM/start and paste that value in ROM/start – then copy the value in RAM/end and paste it as ROM/end.
修改内存， 把RAM 当成 ROM用