HCS08 datasheet(268/316 Pages) NXP

268 / 316 page

MC9S08SG8 MCU Series Data Sheet, Rev. 8

268

Freescale Semiconductor

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 Table 17-1 to describe the coding structure of the BDC commands.

Commands begin with an 8-bit hexadecimal command code in the host-to-target

direction (most significant bit first)

= separates parts of the command

delay 16 target BDC clock cycles

AAAA

a 16-bit address in the host-to-target direction

8 bits of read data in the target-to-host direction

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

the contents of BDCSCR in the target-to-host direction (STATUS)

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

WBKP

16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)

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