MC68HC16Z1 Datasheet, PDF (103/500 Pages) Freescale Semiconductor, Inc – M68HC16Z Series

Freescale Semiconductor, Inc.
of BKPT or execution of the BGND instruction. IPIPE0 and IPIPE1 change function be-
fore an exception signal can be generated. The development system must use
FREEZE assertion as an indication that BDM has been entered. When BDM is exited,
FREEZE is negated before initiation of normal bus cycles. IPIPE0 and IPIPE1 are valid
when normal instruction prefetch begins.
4.14.4.4 BDM Commands
Commands consist of one 16-bit operation word and can include one or more 16-bit
extension words. Each incoming word is read as it is assembled by the serial interface.
The microcode routine corresponding to a command is executed as soon as the com-
mand is complete. Result operands are loaded into the output shift register to be shift-
ed out as the next command is read. This process is repeated for each command until
the CPU returns to normal operating mode. The BDM command set is summarized in
Table 4-7. Refer to the CPU16 Reference Manual (CPU16RM/AD) for a BDM com-
mand glossary.
Table 4-7 Command Summary
Command
Read Registers
from Mask
Write Registers
from Mask
Read MAC Registers
Write MAC Registers
Read PC and SP
Write PC and SP
Read Data Memory
Write Data Memory
Read Program Memory
Write Program Memory
Execute from Current
PK : PC
Null Operation
Mnemonic
RREGM
WREGM
RDMAC
WRMAC
RPCSP
WPCSP
RDMEM
WDMEM
RPMEM
WPMEM
GO
NOP
Description
Read contents of registers specified by command
word register mask
Write to registers specified by command word
register mask
Read contents of entire multiply and accumulate
register set
Write to entire multiply and accumulate register set
Read contents of program counter and stack pointer
Write to program counter and stack pointer
Read byte from specified 20-bit address in data
space
Write byte to specified 20-bit address in data space
Read word from specified 20-bit address in program
space
Write word to specified 20-bit address in program
space
Instruction pipeline flushed and refilled; instructions
executed from current PC – $0006
Null command performs no operation
4.14.4.5 Returning from BDM
BDM is terminated when a resume execution (GO) command is received. GO refills
the instruction pipeline from address (PK : PC – $0006). FREEZE is negated before
the first prefetch. Upon negation of FREEZE, the BDM serial subsystem is disabled
and the DSO/DSI signals revert to IPIPE0/IPIPE1 functionality.
M68HC16 Z SERIES
USER’S MANUAL
CENTRAL PROCESSING UNIT
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