SC312XDP512F0MPVR datasheet(574/1348 Pages) FREESCALE

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Chapter 15 Background Debug Module (S12XBDMV2)

MC9S12XDP512 Data Sheet, Rev. 2.21

574

Freescale Semiconductor

15.3.2.1

BDM Status Register (BDMSTS)

Figure 15-3. BDM Status Register (BDMSTS)

Read: All modes through BDM operation when not secured

Write: All modes through BDM operation when not secured, but subject to the following:

— ENBDM should only be set via a BDM hardware command if the BDM ﬁrmware commands

are needed. (This does not apply in special single chip and emulation modes).

— BDMACT can only be set by BDM hardware upon entry into BDM. It can only be cleared by

the standard BDM ﬁrmware lookup table upon exit from BDM active mode.

— CLKSW can only be written via BDM hardware WRITE_BD commands.

— All other bits, while writable via BDM hardware or standard BDM ﬁrmware write commands,

should only be altered by the BDM hardware or standard ﬁrmware lookup table as part of BDM

command execution.

ENBDM

BDMACT

0SDV

TRACE

CLKSW

UNSEC

Reset

Special Single-Chip Mode

1 ENBDM is read as 1 by a debugging environment in special single chip mode when the device is not secured or secured but

fully erased (Flash and EEPROM). This is because the ENBDM bit is set by the standard ﬁrmware before a BDM command

can be fully transmitted and executed.

3 UNSEC is read as 1 by a debugging environment in special single chip mode when the device is secured and fully erased,

else it is 0 and can only be read if not secure (see also bit description).

Emulation Modes

2 CLKSW is read as 1 by a debugging environment in emulation modes when the device is not secured and read as 0 when

secured.

All Other Modes

= Unimplemented, Reserved

= Implemented (do not alter)

= Always read zero

Table 15-2. BDMSTS Field Descriptions

Field

Description

ENBDM

Enable BDM — This bit controls whether the BDM is enabled or disabled. When enabled, BDM can be made

active to allow ﬁrmware commands to be executed. When disabled, BDM cannot be made active but BDM

hardware commands are still allowed.

0 BDM disabled

1 BDM enabled

Note: ENBDM is set by the ﬁrmware out of reset in special single chip mode and by hardware in emulation

modes. In special single chip mode with the device secured, this bit will not be set by the ﬁrmware until

after the EEPROM and Flash erase verify tests are complete. In emulation modes with the device

secured, the BDM operations are blocked.

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