MC9S12ZVL: How can I enter special modes?

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MC9S12ZVL: How can I enter special modes?

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George_Ye
Contributor II
CPMUVREGCTL register is written in special modes?what is it?And How can I enter special modes?
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lama
NXP TechSupport
NXP TechSupport

Hi,

As I wrote before, the special mode is in this case the only debug mode. The MCU stops and waits for BDM command. Do not mix debugger and emulator. These are two different things. This MCU does not provides emualation mode..

There is no possibility to change mode from normal to special. Have you read the chapter I have directed you - chapter 4.3.2.1 Mode Register (MODE). The only possible change is from special(debug) to normal mode.

Best regards,

Ladislav

Best regards,

Ladislav

 

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lama
NXP TechSupport
NXP TechSupport

Hi,

As I wrote before, the special mode is in this case the only debug mode. The MCU stops and waits for BDM command. Do not mix debugger and emulator. These are two different things. This MCU does not provides emualation mode..

There is no possibility to change mode from normal to special. Have you read the chapter I have directed you - chapter 4.3.2.1 Mode Register (MODE). The only possible change is from special(debug) to normal mode.

Best regards,

Ladislav

Best regards,

Ladislav

 

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lama
NXP TechSupport
NXP TechSupport

Hi,

Excluding explanation about security when the MCU is locked for external access (the only MassErase command from BDM is accepted) there are four modes the MCU can be entered to:

Unsecured Normal Single Chip mode
Unsecured Special Single Chip mode.
Secured Normal Single Chip mode.
Secured Special Single Chip mode.

This is simple processor from modes point of view (no external bus, no emulation mode as it was for older devices) The MCU enters into its mode during reset sequence on the basis of MODC pin which is copied into MODE register. (1.10.2 Chip Configuration Modes)
Simly you can start MCU in the special mode keeping MODC pin at 0 during reset. This mode stops execution of the code after reset, enters into the BDM mode (so called Special single chip mode) and waits for BDM commands. ( used for debugging, debug interface is connected to a MODC pin to start MCU in this mode)
There is the only one transition of the mode possible by writing a value to the bit MODC in the MODE register as describedin the chapter 4.3.2.1 Mode Register (MODE).

It is worth to mention that some registers are writeable anytime in a special (debug) mode and the only once in the normal mode (MODC pin is connected to log. 1 during reset). This is one source of issues the ctms make. They play a game, during debugging, with some register/s which can be written anytime and everything works. Then they start the MCU in normal mode and suddenly it is not working because the same register/s is write once only in the normal mode.

Best regards,

Ladislav

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George_Ye
Contributor II

Hi@lama ,

  Can I simply assume that the special mode is the debug mode? The MCU can only enter the special mode by connecting to the emulator. In this case, can I not directly switch from normal mode to the special mode?

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