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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from all low-power modes. The LFO is always active and cannot be powered off by any
software control. The control bits for the RTI are shown in Table 175.
Note: Regarding wake-up from Stop1, the reset vector is accessed, taking precedence
over the interrupt vector.
10.8 Modes of operation
The operating modes of the NTM88 are described in this section. Entry into each mode,
exit from each mode, and functionality while in each of the modes is described.
10.8.1 Features
• ACTIVE BACKGROUND DEBUG mode for code development
• STOP modes:
– System clocks stopped
– STOP1: Power down of most internal circuits, including RAM, for maximum power
savings; voltage regulator in standby
– STOP4: All internal circuits powered and full voltage regulation maintained for fastest
recovery
10.8.2 RUN mode
This is the normal operating mode for the NTM88. This mode is selected when the
BKGD/PTA4 pin is high at the rising edge of reset. In this mode, the CPU executes code
from internal memory following a reset with execution beginning at address specified by
the reset pseudo-vector ($DFFE and $DFFF).
10.8.3 WAIT mode
The WAIT mode is also present like other members of the NXP S08 family members; but
is not normally used by the NTM88 firmware or typical TPMS applications.
10.8.4 ACTIVE BACKGROUND mode
The ACTIVE BACKGROUND mode functions are managed through the BACKGROUND
DEBUG controller (BDC) in the HCS08 core. The BDC provides the means for analyzing
MCU operation during software development.
ACTIVE BACKGROUND mode is entered in any of four ways:
• When the BKGD/PTA4 pin is low at the rising edge of a power-up reset
• When a BACKGROUND command is received through the BKGD/PTA4 pin
• When a BGND instruction is executed by the CPU
• When encountering a BDC breakpoint
Once in ACTIVE BACKGROUND mode, the CPU is held in a suspended state waiting
for serial BACKGROUND commands rather than executing instructions from the user’s
application program. Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user
program is running. Non-intrusive commands can be issued through the BKGD/PTA4
pin while the MCU is in RUN mode; non-intrusive commands can also be executed
when the MCU is in the ACTIVE BACKGROUND mode. Non-intrusive commands
include:
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