Application Overview

AN4515

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DocID026482 Rev 1

1.2

Low-power modes

This section describes the different low-power modes used in the application.

•

Low-power run mode

The CPU and some of the peripherals are running. To further reduce power

consumption, unused GPIOs configured as analog pins and peripherals are disabled.

•

Sleep mode

In this mode only the CPU is stopped and the peripherals kept running. To reduce

power consumption the Flash memory can be stopped before entering Sleep mode.

Peripherals can wake up the CPU when an interrupt occurs.

•

Stop mode

The CPU is in DeepSleep mode. All peripherals except RTC are disabled. Exiting Stop

mode is done by issuing an interrupt.

•

Standby mode

In this mode the power is only maintained for the RTC registers. The device is woken

by a rising edge on the WKUP pin that generates a system reset.

Note:

For more details about the low-power modes refer to STM32F411xx datasheets.

1.3

Batch Acquisition Mode (BAM)

1.3.1

Principle

The Batch Acquisition Mode (BAM) optimizes power consumption for data batching.

It allows exchanging batches of data through communication peripherals while the rest of

the device (including the CPU) is in low-power mode:

•

Only the needed DMA streams are enabled and running to transfer data from

communication interfaces to internal RAM.

•

Routine execution from RAM allows switching off the Flash memory and stopping the

Flash Interface clock.

•

MCU core is put in Sleep mode waiting for an interrupt/event to wake up.

1.3.2

BAM use case

Figure 2 shows one part of the application note use case block diagram. It describes the

different peripherals involved in the BAM and mentions their power state (low-power or

active).

In fact, during data reception, only the DMA stream0, I2C1 and SRAM are active. The MCU

core is in Sleep mode and the Flash memory is stopped until the DMA transfer is complete.