reset in critical system

[samport]

Hi all

kindly can any one help me in this topic.

i was wondering how critical embedded systems in critical applications like planes and cars can overcome a reset( like watch dog reset or broun out reset) to the system, does it restart the system from the begining or there is another mechanism they use to resume work from the point it was reseted at.

best regards to all

samport

 

[j_doe_999]

The way to recover from a reset depends on the system.

In the communication systems I am working on , the processor is used to handle the setup and control, not the traffic. In this case, a watchdog reset affects only the processor, not the hardware used for traffic. After the watchdog reset, the processor restarts and checks the system status. If the traffic is up and running, it will not be afftected.

In the case of brownout reset, because this have to reset all the hardware in the system, the system will do a cold start.

John

 

[samport]

Dear j_doe_999


thanks for your reply.

as I know, the C compiler injects a start up code to zero all static and glopal variables in the RAM , so when the sestem resets how will the microprocessor or microcontroller know if the reset was due to cold reset , watch dog reset or voltage down reset

best regards

Samport

 

[gowthamn]

Hi,

I have come across some instances in design approaches. There is a separate memory termed as NVM in the critical systems, usually the watchdog timer is disabled and the data is moved to NVM. In case there is a power failure the full system will reboot up and then starts executing the last stored data present in the NVM.

I guess you were looking for this concept right.

Cheers
Gowtham

 

[samport]

Hi all,

thanks alot to Gowthamn for his post.

can i ask you Gowthamn some questions?

how can the system do this in the start up while the C compiler inject start up code which make all memory locations zero value?

can i tell the compiler to insert my own start up code?

how can i save the program counter to be restored after a reset?

best regards

Samport