S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
Freescale Semiconductor
141
Chapter 5
Background Debug Controller (S12ZBDCV2)
5.1
Introduction
The background debug controller (BDC) is a single-wire, background debug system implemented in on-
chip hardware for minimal CPU intervention. The device BKGD pin interfaces directly to the BDC.
The S12ZBDC maintains the standard S12 serial interface protocol but introduces an enhanced handshake
protocol and enhanced BDC command set to support the linear instruction set family of S12Z devices and
offer easier, more flexible internal resource access over the BDC serial interface.
5.1.1
Glossary
Table 5-1. Revision History
Revision
Number
Revision
Date
Sections
Affected
Description of Changes
V2.04
03.Dec.2012
Included BACKGROUND/ Stop mode dependency
V2.05
22.Jan.2013
Improved NORESP description and added STEP1/ Wait mode dependency
V2.06
22.Mar.2013
Improved NORESP description of STEP1/ Wait mode dependency
V2.07
11.Apr.2013
Improved STOP and BACKGROUND interdepency description
V2.08
31.May.2013
Section 5.4.4.4
Section 5.4.7.1
Removed misleading WAIT and BACKGROUND interdepency description
Added subsection dedicated to Long-ACK
V2.09
29.Aug.2013
Noted that READ_DBGTB is only available for devices featuring a trace
buffer.
V2.10
21.Oct.2013
Improved description of NORESP dependence on WAIT and BACKROUND
V2.11
02.Feb.2015
Corrected name of clock that can stay active in Stop mode
Table 5-2. Glossary Of Terms
Term
Definition
DBG
On chip Debug Module
BDM
Active Background Debug Mode
CPU
S12Z CPU
SSC
Special Single Chip Mode (device operating mode)
NSC
Normal Single Chip Mode (device operating mode)
BDCSI
Background Debug Controller Serial Interface. This refers to the single pin BKGD serial interface.
EWAIT
Optional S12 feature which allows external devices to delay external accesses until deassertion of EWAIT