Bdc Commands - ROHS MC9S08QE128 Reference Manual

17.2.3

BDC Commands

BDC commands are sent serially from a host computer to the BKGD pin of the target HCS08 MCU. All
commands and data are sent MSB-first using a custom BDC communications protocol. Active background
mode commands require that the target MCU is currently in the active background mode while
non-intrusive commands may be issued at any time whether the target MCU is in active background mode
or running a user application program.
Table 17-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command.
Coding Structure Nomenclature
This nomenclature is used in
Commands begin with an 8-bit hexadecimal command code in the host-to-target
direction (most significant bit first)
/ = separates parts of the command
d = delay 16 target BDC clock cycles
AAAA = a 16-bit address in the host-to-target direction
RD = 8 bits of read data in the target-to-host direction
WD = 8 bits of write data in the host-to-target direction
RD16 = 16 bits of read data in the target-to-host direction
WD16 = 16 bits of write data in the host-to-target direction
SS = the contents of BDCSCR in the target-to-host direction (STATUS)
CC = 8 bits of write data for BDCSCR in the host-to-target direction (CONTROL)
RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)
Freescale Semiconductor
Table 17-1 to describe the coding structure of the BDC commands.
MC9S08QE128 MCU Series Reference Manual, Rev. 2
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