配置spc5744 SWT复位后不清零变量

zhangzhixing

我的map 文件中已经配置好了一个 noinit 变量，但是用multilink debug的时候，SWT复位后清零了，我禁止了.S 中的初始化 SRAM 的代码，也是清零的，是否能提供一个比较全面的方案来实现这个功能。

petervlna

Hello,

The debugger disable SWT by default. So you can debug and not be reset on SWT timeout by counter running in background.

Google translate:

A noinit variable has been configured in my map file, but when using multilink debug, the SWT is cleared after reset. I disabled the code for initializing SRAM in .S, and it was also cleared. Can you provide a more comprehensive solution to implement this function?

Hopefully I understand your questions from translate. If not, please formulate it in English.

Best regards,

Peter

zhangzhixing

I removed the debugger ，The MCU sends the value by the CAN interface，got zero for my variable which should be 0xAA06 .

petervlna

Hello,

Unfortunately I am not able to understand the question.

Could you reformulate it in a more clear way so I can guide you?

Best regards,

Peter

zhangzhixing

in the LD file, the Noinit SRAM area is set. Startup.s didn't clear it, and the Mac file removed the clearing operation. A variable in this area is defined in main.c and has been referenced. In the map file, I found the address allocation text for variables. After the SWT reset, I found this variable was still cleared. Could you tell me the reason?

petervlna

Hello,

Ok, so you basically want to preserve RAM content trough reset.

You have set the area in RAM where the data should be preserved as noinit - so RAM initialization is not done on this area.

After SWT reset you see the area filled with ECC. = reset state of RAM

SWT triggers functional reset -

So the SRAM is preserved after functional reset.

Here I expect you are not doing RAM init at all, as it is still preserved.

But what can cause behavior you see is destructive reset or power on reset:

So I will just blind shot that you have reset escalation scenario:

When you see the RAM not initialized, check the content of RGM [DES] to see the source of you issue. It must be destructive reset.

Best regards,

Peter