how to init the watchdog for MPC5748G

[happy_larry]

Hi everyone,

I'm trying to devolopment the bootloader for MPC5748G, we meet a problme about the watchdog.

We have used the default project configuration of S32 V1.0 for power, and we changes nothing for the interrupt vector table.

Then we used the below code to init the watchdog after call the xcptn_xmpl. When we want to write the specifed value into SWT, err will occurs. Acturally, both read and write of the SWT register will cause the err. The CPU will go to IVOR1_Vector. We have checked that the pointer to the SWT is correct. SWT_0 is start from 0xFC050000 and the SWT_0.SR is 0xFC050010.

Can anyone know how to init the watchdog or help me to solve the problem?

void Wdg_Init(void)

{

while(MC_ME.GS.B.S_SIRCON != 1U)

{

/* SWT must be configured only if the 128 KHz internal

        RC oscillator is providing a stable clock */

}

SWT_0.SR.R = 0xC520U;       /* error occurs here, CPU will go to IVOR1_Vector.*/

SWT_0.SR.R = 0xD928U;      

/* WDG can only be serviced with fixed sequence */

SWT_0.CR.B.SMD = 0U;

/* Generate a reset on a time-out */

SWT_0.CR.B.ITR = 0U;

    /* Invalid access to the SWT causes a system reset */

SWT_0.CR.B.RIA = 1U;

/* SWT continues to run in stop mode */

SWT_0.CR.B.FRZ = 1U;

/* SWT continues to run in stop mode */

SWT_0.CR.B.STP = 0U;

/* Set time-out clock cycles */

SWT_0.TO.R = WDG_TIMEOUT_VALUE;

/* SWT enabled */

SWT_0.CR.B.WEN = 1U;

/* Make the WDG enter soft lock mode */

SWT_0.CR.B.SLK = 1U;

}

[alexvinchev]

Hi,

can  you try this code:

;	SWT_0.SR.R = 0xc520;
	e_lis	r12, -0x3FB
	e_li	r0,  0xC520
	e_li	r11, 0xD928
;	SWT_0.SR.R = 0xd928;
	e_stw	r0,  0x10(r12)  # r0,16(r12)
	e_lis	r0,  -0x1000
	e_stw	r11, 0x10(r12)  # r11,16(r12)
;	SWT_0.CR.R = 0xFF00010A;
	e_add16i	r0,r0,0x10A
	e_stw	r0,  0x0(r12)   # r0,0(r12)

Add it as close as possible to your start point (before ECC RAM init). This code disables the STW0, but in your case will prove that you can or you can not write to SWT_0.SR.R.

[happy_larry]

Thanks very much for you replay!

I will try your solution.

[martin_kovar · Accepted solution]

Hi,

this problem becomes, because during startup, core access to SWT is disabled (this is the IVOR1 reason).

Look at the startup code (section Turn off SWTs) and update the last three lines with the following code:

e_lis    r3, 0xFF00

e_or2i    r3, 0x010A

e_stw    r3, 0(r4)

Now you should be able to configure SWT.

Regards,

Martin