MC68HC08AS32 Datasheet, PDF (59/280 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

the MCU’s possible reset sources (such as LVR, POR, COP watchdog, and reset
pin, etc.) is asserted.
In reset mode, the internal BDLC voltage references are operative; V_DD is supplied
to the internal circuits which are held in their reset state; and the internal BDLC
system clock is running. Registers will assume their reset condition. Outputs are
held in their programmed reset state. Therefore, inputs and network activity are
ignored.
4.3.1.3 Run Mode
This mode is entered from the reset mode after all MCU reset sources are no
longer asserted. Run mode is entered from the BDLC wait mode whenever activity
is sensed on the J1850 bus.
Run mode is entered from the BDLC stop mode whenever network activity is
sensed, although messages will not be received properly until the clocks have
stabilized and the CPU is in run mode also.
In this mode, normal network operation takes place. The user should ensure that
all BDLC transmissions have ceased before exiting this mode.
4.3.1.4 BDLC Wait Mode
This power-conserving mode is entered automatically from run mode whenever the
CPU executes a WAIT instruction and if the WCM bit in the BCR1 register is
cleared previously.
In this mode, the BDLC internal clocks continue to run. The first passive-to-active
transition of the bus generates a CPU interrupt request from the BDLC which
wakes up the BDLC and the CPU. In addition, if the BDLC receives a valid EOF
symbol while operating in wait mode, then the BDLC also will generate a CPU
interrupt request which wakes up the BDLC and the CPU. See 4.7.1 Wait Mode.
4.3.1.5 BDLC Stop Mode
This power-conserving mode is entered automatically from run mode whenever the
CPU executes a STOP instruction or if the CPU executes a WAIT instruction and
the WCM bit in the BCR1 register is set previously.
In this mode, the BDLC internal clocks are stopped but the physical interface
circuitry is placed in a low-power mode and awaits network activity. If network
activity is sensed, then a CPU interrupt request will be generated, restarting the
BDLC internal clocks. See 4.7.2 Stop Mode.
4.3.1.6 Digital Loopback Mode
When a bus fault has been detected, the digital loopback mode is used to
determine if the fault condition is caused by failure in the node’s internal circuits or
MC68HC08AS32 — Rev. 4.1
Freescale Semiconductor
Data Sheet
59