topic Re: HCS08: There is no "reset" instruction? in 8-bit Microcontrollers

HCS08: There is no "reset" instruction?

BasePointer — Thu, 08 Feb 2007 16:28:15 GMT

Hi,

I want to reset the MCU at some conditions.

But there is no instruction to do this with HCS08.

How can I reset the MCU without using COP?

MCU is MC9S08LC60.

Thank you.

Re: HCS08: There is no "reset" instruction?

Nouchi — Thu, 29 Oct 2020 08:45:41 GMT

Hello,

You can generate RESET by doing illegal operation, you can find an example in AN2295

Code:

ILOP        MACRO            DC.B    $8d             ; this is illegal operation code            ENDM

call this macro and processor will reset with illegal opcode (you can see that in SRS register and ILOP flag)

Emmanuel

Re: HCS08: There is no "reset" instruction?

Alban — Thu, 08 Feb 2007 17:13:50 GMT

Hello,

BugMan's method is also my prefered.

You can also generate an ILAD (Execute from Illegal Address), by doing

JMP 0x00;

0x00 is not a code region but registers.

I prefer ILOP as an ILAD is more likely to happen in code runaway situations.

Therefore I prefer my software to know when a real ILAD occured.

Cheers,

Alban.

Re: HCS08: There is no "reset" instruction?

BasePointer — Thu, 29 Oct 2020 08:45:43 GMT

Hi BugMan,

How can I use this in C?

Code:

if(++SOFTWARE_WATCHDOG > 200) asm("DC.B $8d");Error: C18125: Invalid opcode or ':' expected

Thanks.

Re: HCS08: There is no "reset" instruction?

BasePointer — Thu, 29 Oct 2020 08:45:45 GMT

Hi Alban,

Code:

if(++SOFTWARE_WATCHDOG > 200) asm("JMP 0x00");

This is compiled succesfully. But I wonder is this real reset or just jump to 0?

Can I re-initialize one-time writeable registers after this reset?

Will all registers set back to their reset values?

Thank you.

Re: HCS08: There is no "reset" instruction?

Nouchi — Thu, 08 Feb 2007 18:31:39 GMT

Hi,

The first solution comes to my mind, is to write a pure asm function (not in lined), and call the function in your C file. The Inline assembler seems to be quite strict.

Emmanuel

Re: HCS08: There is no "reset" instruction?

Alban — Thu, 08 Feb 2007 18:42:10 GMT

Hi,

0x00 cannot be executed from as the MCU knows it is a register area.

Therefore a jump to 0 will trigger an Illegal Address Reset (ILAD Flagged).

All registers go to their reset value, and write-once are released like if it was a PIN Reset.

Cheers,

Alban.

Re: HCS08: There is no "reset" instruction?

peg — Thu, 08 Feb 2007 18:46:31 GMT

Hi,

Take a look here:

http://forums.freescale.com/freescale/board/message?board.id=8BITCOMM&message.id=208

for some other ideas on this.

Re: HCS08: There is no "reset" instruction?

Alban — Thu, 29 Oct 2020 08:45:47 GMT

Code:

if(++SOFTWARE_WATCHDOG > 200)    {                       /* Generate a RESET by Illegal Opcode */   asm DCB 0x8D ;   }

This does work.

Alban.

Re: HCS08: There is no "reset" instruction?

BasePointer — Thu, 08 Feb 2007 19:37:29 GMT

Hi Alban,

asm("jmp 0x00"); -> doesn't generate illegal opcode reset for me. The application crashs with it.

But this worked as I expected.

if(++SOFTWARE_WATCHDOG > 200) asm("DCB 0x8D");

Thank you so much.

Re: HCS08: There is no "reset" instruction?

Alban — Thu, 08 Feb 2007 20:06:59 GMT

Thanks for the feedback BP, may be the S08 doesn't behave as I thought.

I find it abnormal though.

Manu/Peg ?

Any experience on this ILAD ?

I will Read The Factory Manual and see...

Alban.

Re: HCS08: There is no "reset" instruction?

Alban — Thu, 08 Feb 2007 20:17:16 GMT

Everything is OK.

The confidential product you are talking about does not feature ILAD.

Same for GB60.

Alban.

Re: HCS08: There is no "reset" instruction?

peg — Fri, 09 Feb 2007 05:42:33 GMT

Ahhh!

So this is what Rocky meant by "there are no illegal addresses on a GB60" in my "QG BKGD issues" thread!

All newer A version 'less than 60' GB/GT's have it re-instated.