Chapter 19 Background Debug Module (S12XBDMV2)
MC9S12XDP512 Data Sheet, Rev. 2.11
768 Freescale Semiconductor
19.2 External Signal Description
A single-wire interface pin called the background debug interface (BKGD) pin is used to communicate
with the BDM system. During reset, this pin is a mode select input which selects between normal and
special modes of operation. After reset, this pin becomes the dedicated serial interface pin for the
background debug mode.
19.3 Memory Map and Register Definition

19.3.1 Module Memory Map

Table 19-1 shows the BDM memory map when BDM is active.
Table 19-1. BDM Memory Map
Global Address Module Size
(Bytes)
0x7FFF00–0x7FFF0B BDM registers 12
0x7FFF0C–0x7FFF0E BDM firmware ROM 3
0x7FFF0F Family ID (part of BDM firmware ROM) 1
0x7FFF10–0x7FFFFF BDM firmware ROM 240