Is there ram/register that will survive through reset R274

[markthompson170]

Hi All

I looking for a way to pass data through a hard reset. IE a register or ram that is not pre-configured when a reset is applied.

Is there ram/register that will survive through reset in the R274.

I only need a few bytes.

I am currently using the SIPI regs to pass data through software resets but they don't survive any sort of hard reset.

Thanks

Mark

[davidtosenovjan]

Hi, it seems on this device only Software reset is the one, over which RAM content is preserved. You must then examine reset cause and if it is Software reset then you may omit some portion of SRAM initialization.

[markthompson170]

HI David

I’m thinking I can use the SPRG0-3 regs to hold my data and a software reset. This seems to work fine - asm (" mtspr 272, %r3");

I don’t know a lot about PPC architecture, but I can’t figure out how the cause a software interrupt.

The MC_RGM handles the conditions but nothing I can locate indicates how to cause one.

Is the a special PPC instruction for softreset ?

Is there a system hardware block I need access ?

Thanks

Mark

[davidtosenovjan]

It seems SPRG0-3 have no defined functionality so they can be used by application software.

Use the MC_ME module to enter the RESET mode (SW functional reset):

/* software reset */    
ME.MCTL.R = 0x00005AF0;
ME.MCTL.R = 0x0000A50F;

This sequence resets the device.

[markthompson170]

Thanks David

This seem to work great.

Mark

[petervlna]

Hi,

from your description I am not sure about which kind of hard reset are you talking.

Reset divide to :

Power on reset - all registers are reset

Destructive resets

Functional resets

You can use one of the core registers: Undefined on m_por assertion, unchanged on p_reset_b assertion

List of them is in z7 core reference manual  Table 2-16. Reset Settings for e200 Resources.

https://www.nxp.com/docs/en/reference-manual/e200z760RM.pdf 

Peter