MC33989PEG Freescale Semiconductor, MC33989PEG Datasheet - Page 22

• Manufacturer Part Number: MC33989PEG
• Description: SBC-HS
• Manufacturer: Freescale Semiconductor

FUNCTIONAL DEVICE OPERATION
RESET AND WATCHDOG PINS, SOFTWARE WATCHDOG OPERATIONS
APPLICATION WAKE-UP FROM MCU SIDE
by a low to high transition on the CS pin. Then the SBC goes into Normal Request mode and generates an interrupt pulse at the
INT pin.
STOP MODE CURRENT MONITOR
generates an interrupt at the INT pin. The interrupt is not maskable and the interrupt register will has no flag set.
INTERRUPT GENERATION WHEN WAKE-UP FROM STOP MODE
on the INT pin. These interrupts are not maskable, and the wake-up event can be read through the SPI registers (CANWU bit in
Reset Control Register (RCR) and LCTRx bit in Wake-up Register (WUR). In case of wake-up from Stop mode over current or
from forced wake-up, no bit is set. After the INT pulse the SBC accept SPI command after a time delay (t
SOFTWARE WATCHDOG IN STOP MODE
to do this, the MCU must signal the wake-up to the SBC through the SPI wake-up (CS activation). The SBC then wakes up and
jumps into the Normal Request mode. MCU has to configured the SBC to go to either Normal or Standby mode. The MCU can
then decide to go back again to Stop mode.
Normal Request mode. The MCU can then be initialized.
STOP MODE ENTER COMMAND
Dynamic Electrical
MCU to complete the last CPU instruction, allowing the MCU to enter its low power mode, a deglitcher time of typical 40 µs is
implemented.
SOFTWARE WATCHDOG (SELECTABLE WINDOW OR TIMEOUT WATCHDOG)
timeout. This is selectable by SPI (register TIM1, bit WDW). Default is window watchdog. The period for the watchdog is
selectable from the SPI from 10 ms to 350 ms (register TIM1, bits WDT0 and WDT1). When the window watchdog is selected,
the closed window is the first part of the selected period, and the open window is the second part of the period. Refer to the SPI
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33989
When application is in Stop mode, the wake-up event may come from the MCU side. In this case the MCU signals to the SBC
If the V
When the SBC wakes up from Stop mode, it first enters the Normal Request mode before generating a pulse (10 µs typical)
If Watchdog is enabled, the MCU has to wake-up independently of the SBC before the end of the SBC watchdog time. In order
When there is no MCU wake-up occurring within the watchdog timing, the SBC activates the Reset pin, jumping into the
Stop mode is entered at the end of the SPI message, and at the rising edge of the CS. Please refer to the t
Once Stop mode is entered the SBC could wake-up from the V1 regulator over-current detection. In order to allow time for the
Figure 9
Software watchdog uses in the SBC Normal and Standby modes is to monitor MCU. The Watchdog can be either window or
SPI Stop/ Sleep Command
DD1
indicates the operation to enter Stop mode.
output current exceed an internal threshold (I
SPI CS
Characteristics.
RESET AND WATCHDOG PINS, SOFTWARE WATCHDOG OPERATIONS
SBC in Normal or Stand-by mode
Figure 9. Operation Entering Stop Mode
t
DD1SWU
CS
STOP
), the SBC goes automatically into Normal Request mode and
no I
SBC in Stop mode
DD1
I
DD1DGLT
over I wake-up
Analog Integrated Circuit Device Data
SBC in Stop mode
with I
Freescale Semiconductor
DD1
S1STSPI
over I wake-up
CSSTOP
parameter).
data in the