NXP Semiconductors
UM11227
NTM88 family of tire pressure monitor sensors
UM11227 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 6 — 24 April 2020
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Earliest start of next bit
aaa-028045
Host samples BKGD PTA4 pin
10 cycles
BDC clock
(target MCU)
Host drive to
BKGD/PTA4 pin
BKGD/PTA4 pin
Target MCU
drive and
speedup pulse
Perceived start
of bit time
10 cycles
High-impedance
Speedup
pulse
Figure 10. BDM target-to-host serial bit timing (Logic 0)
9.2.3 BDC commands
BDC commands are sent serially from a host computer to the BKGD/PTA4 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 10 shows all HCS08
BDC commands, a shorthand description of their coding structure, and the meaning of
each command.
9.2.3.1 Coding structure nomenclature
This nomenclature is used in Table 10 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
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
RD!6 = 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)
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