Low Power Support And Stop Mode Implementation - STMicroelectronics SPC572L series Reference Manual

RM0400
9.2.1

Low power support and STOP mode implementation

Low power mode may be used to control the engine during the power-up phase, as in a
Start-Stop system or when the key has been turned off.
After-run is defined as part of RFQ500, the requirement has since been clarified as follows.
The device implements the equivalent of an idle or power-down mode through STOP and
HALT mode configuration.
The microcontroller application code can be used to put the device or modules into STOP
mode.
A combination of mode control and clock control allows the user to configure the STOP
mode.
In After-run mode, peripheral modules can be enabled/disabled in STOP using the control
described in the Mode Entry control section. For example, it is possible to make two CAN
modules, one ASC module and a few requested pins active. For alternate configurations,
other modules can be enabled/disabled in STOP using the control described in the Mode
Entry section. External interrupt request channels and external wake-up channels can be
actived to wake-up the device as alternatives to peripherals interrupts.
All pins associated with the active modules are functional. Control of the pins is defined by
user during run-time. A wake-up line is associated with each selectable module.
One of the available modules can be configured to perform the wake-up task. For example,
with n CAN modules on the chip, one is configured to receive wake-up signals and the
others are set to power-down completely. Any of the modules can be configured to do this.
All CAN modules can be independently configured to receive messages and respond to
wake-up messages. Control of the pins is defined by user during run-time.
These modules can also be idle in idle mode, but wake-up and wake the core as soon as
activity is detected.
All these modules can be configured to a low power state. Wake-up recovery is
programmable: for instance, depending on the state or activity of the associated pin.
All parts of the device can be disabled. The following modules are configurable:
•
There is one CAN module, selectable from any of the CAN modules on the device. The
others can be disabled.
–
–
•
One LIN/UART module is able to recognize special wake-up messages on the receive
line and then wake up the controller.
•
Some request pins are able to initiate a wake-up. Refer to the pinout chapter for more
information.
• The system timer (PIT) is able to initiate a wake-up.
Configurable modules (ASC, two CANs, timer) can all be off in STOP mode.
The CAN module recovers from wake-up instantaneously but its ability to capture the
message depends on settings of certain peripherals such as the CAN protocol clock. SInce
the recovery time impacts whether the first message can be captured, software must be
used as a workaround.
The maximum CAN baud rate is 1 MBaud.
One CAN module is able to receive messages from the CAN bus and wake-up the
controller if the received message contains the correct message identifier.
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