MC33907 WDT reset

[manuelaielo]

Hi,
I'm using a MPC5643L connected to MC33907 as SBC. If the SBC causes a reset to the MCU because it finds a WDT error, at the next power on is there any way to discover that there have been a WDT SBC reset?

Thank you in advance

Best Regards,

Manuela

[petervlna · Accepted solution]

Hi,

After your SBC trigger reset of microcontroller you can read RGM module DES and FES registers to find out reset source.

For SBC it is an external reset event which is functional reset and its flag is located in FES register.

RGM holds information of reset sources on any reset event except Power On Reset.

When micro loose power (POR) RGM module is reset and information of reset sources is lost.

Peter

[manuelaielo]

Hi Peter,

I have one more question about reset source in the configuration  described above (MPC5643L and MC33907 as SBC )

If I perform a SW functional reset using in the code the command

MC_ME.MCTL.R = 0x00005AF0;          

MC_ME.MCTL.R = 0x0000A50F;   

I expected to read F_SOFT_FUNC as reset source in the FES register, instead I get external reset also in this case.

Is it correct?

Best Regards,

Manuela

[petervlna]

Hi Manuela,

There can be various reasons for external reset.

1. Yes, you will see F_SOFT_FUNC in FES register after writing 0x00005AF0 and 0x0000A50F in MCTL register.

2. External reset can be caused either by debugger or external event on external reset pin.

Disconnect your SBC chip reset line from micro to ensure reset is not coming from SBC.

I just made a test and I can see only F_SOFT_FUNC set in FES after writing to MCTL register.

Peter

[manuelaielo]

I'm using the KIT3390908MBEVBE

I'm running my test without debugger and I verified, with an oscilloscope, that the resetb pin doesn't go down (so the reset it is not caused by SBC) but the reset in TP202 does. What can cause this behavior performing a SW reset?

Thank you in advance

Manuela

[petervlna]

I am not sure from you description of issue.

But make sure " you have nothing connected to external reset pin".

Then you cannot see any external reset in FES register.

I am pretty sure that external reset you see in FES is caused by polling external reset pin on micro from some other device, like SBC chip or debugger.

Peter

[manuelaielo]

Thank you Peter

Best Regards,

Manuela