topic Re: LockStep mode and dual parallel mode in MPC5xxx

LockStep mode and dual parallel mode

pramodkashyap — Wed, 06 Sep 2017 15:08:59 GMT

Hello All,

Iam doing a project on EPS(electronic power steering),

Iam looking for a Micro controller with ASIL D complaint,

I looked at this Lockstep mode and dual parallel mode with dual core controllers,

Please can somebody let me know how this two modes will be useful in Hardware/software point of view.

Thanks & Regards,

Pramod Kashyap

Re: LockStep mode and dual parallel mode

davidtosenovjan — Wed, 06 Sep 2017 17:58:29 GMT

I am attaching several slides describing MPC5643L architecture. It offers two modes LSM and DPM. Page 2 shows their comparison.

Page 3 shows spheres of replication (i.e. Lake) executing the same tasks in LSM mode.

On the place, where replicated and non-replicated part touches, lies redundancy checker. It checks whether bus content is equal - if no, fault is reported to FCCU module and FCCU takes appropriate action (MCU can go to safe mode, interrupt or reset can occur according to particular fault severity, report this condition to supervisory system on FCCU pins and so on).

Typical application is in the systems where possible faults are not easily tolerated and malfunction could lead in injuries or damages of people health. It is called safety systems. Examples:

Airbag Systems, Electronic Stability Control, Electric Power Steering, Braking, …

In non-automotive applications Robotics, Industrial Automation, Medical Appliances and so on…

Another point why to use LSM mode for developing your safety application is existence of safety manual what's such guide telling how to develop functional safety system:

http://www.nxp.com/docs/en/user-guide/MPC5643LSM.pdf

You may see following white paper discussing DPM/LSM pros and cons:

http://www.nxp.com/docs/en/white-paper/MPC564XLWP.pdf

To simplify it - LSM is mode is suitable for safety application, DPM for applications where more performance is needed (and integrated special safety HW is disabled).

Re: LockStep mode and dual parallel mode

pramodkashyap — Thu, 07 Sep 2017 06:28:14 GMT

Thanks a lot for response David,

By using the Dual core with lock step mode feature can i reduce the two micro controller architecture in aspect of Hardware as well as software design in functional safety with ASIL D complaint system,

Please can you elaborate more on this doubt.