Configuring FCCU while running it on IRCOSC gives configuration timeout error

[ignatiusmichael]

Hi all,

I am trying to configure FCCU for MPC5777C. when i configure it after PLL initialization where fm_per_clk = 132MHz

Everything works fine and FCCU gets configured. 

But when i move the same piece of code before PLL initialization such that the system is running on IRCOSC , my code execution gets stuck at the configuration state and CFG_TO_STAT field in FCCU_IRQ_STAT indicates a configuration timeout error (this does not happen when running at 132 MHz). 

my FCCU_CFG_TO is set to its default value 0x6.

and in my config operation right after OP1 execution  i am just enabling faults and alarms for them. in 3 instructions before switching to normal state.

Thanks

[petervlna]

Hi,

There is no issue running FCCU configuration from IRC clock.

Actually, FCCU is clocked by IRC clock (which is considered as safe clock).

I will explain your situation:

Once you unlock FCCU and move to configuration state, FCCU starts its internal configuration watchdog (not programable).

If this watchdog expires FCCU reports configuration timeout.

Also once you are in configuration state you can only work with FCCU registers (if you work with other peripherals you will get fault).

Write a simple example and replace with it the failing code:

1. unlock FCCU

2. move to config state

3. move to normal state

regards,

Peter

[ignatiusmichael]

Hi Peter,

First of all thanks a lot for your speedy reply, so i followed your steps and was able to debug the issue myself.

I was running a do while operation to put FCCU in Config state so that if OPS was not successful it would try again to put the FCCU in Config state. this worked fine running it in 132 MHz but my execution started getting stuck in the loop in 8 MHz. Removing the looping solved my issue.

 Now everything is working just as expected my registers are being configured and interrupt is being generated after the fault injection and i have no configuration timeout error. BUT my FCCU_STATUS is showing as in CONFIG STATE even after i have exited the function and have interrupts generated.

WHY???

as per my understanding if i am able to get interrupts that means i have successfully configured it else i would have got an configuration timeout error and my configuration register would have been reset.

Is this an issue with the debugger or is it something else.

Thanks