CPU16
REFERENCE MANUAL
DEVELOPMENT SUPPORT
MOTOROLA
10-9
BDM also simplifies in-circuit emulation. In a common setup (
Figure 10-4
), emulator
hardware replaces the target system processor. Communication between target sys-
tem and emulator takes place via a complex interface.
Figure 10-4 In-Circuit Emulator Configuration
CPU16 emulation requires a bus state analyzer only. The processor remains in the tar-
get system (see
Figure 10-5
) and the interface is less complex.
Figure 10-5 Bus State Analyzer Configuration
The analyzer monitors processor operation and the on-chip debugger controls the op-
erating environment. Emulation is much “closer” to target hardware, and interfacing
problems such as limited clock speed, AC and DC parametric mismatch, and restrict-
ed cable length are minimized.
BDM is an alternate CPU16 operating mode. During BDM, normal instruction execu-
tion is suspended, and special microcode performs debugging functions under exter-
nal control.
BDM can be initiated by external assertion of the BKPT input, by internal assertion of
the IMB BKPT signal, or by the BGND instruction. While in BDM, the CPU16 ceases
to fetch instructions via the parallel bus and communicates with the development sys-
tem via a dedicated serial interface.
TARGET
SYSTEM
IN-CIRCUIT
EMULATOR
TARGET
MCU
TARGET
SYSTEM
BUS STATE
ANALYZER
TARGET
MCU
F
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