Low Power Application on SAM L21 Using MPLAB® Harmony v3 Peripheral Libraries: Step 4

Last modified by Microchip on 2023/11/09 09:07

Configure PM, SUPC and NVMCTRL Peripheral libraries, LED and Wake-up Test Pins

Configure Power Manager (PM) Peripheral Library

1. Under the bottom left tab, Available Components, expand Peripherals > PM.

Double-click or drag and drop PM to add the PM peripheral library to the project graph.

Available Components and Project Graph pane

Select the PM peripheral library and configure it as shown below.

  • Set the Performance Level to 0 to reduce the power consumption of the device during Standby mode.
  • Enable PD0 and PD1 Dynamic Power Gating: these options allow the device to turn off a power domain during Standby mode if no peripheral contained in this power domain requests its clock.
  • Set the Voltage Regulator to operate in Low-power oriented mode during standby to reduce the power consumption of the device even more.

Configuration Options pane

Information

This completes the configuration of the PM peripheral library. In Standby mode, the CPU is stopped as well as the peripherals except those which are configured to run in Standby mode. The Standby Sleep mode provides very low power consumption with little overhead on wake-up time. CPU enters Standby mode by executing the Wait for Interrupt (WFI) instruction and exits from the Standby mode when an interrupt is generated.

Back to Top


Configure SUPC Peripheral Library

Under the bottom left tab, Available Components, expand Peripherals > SUPC.

Double-click or drag and drop SUPC to add the Supply Controller (SUPC) peripheral library to the project graph.

Available Components and Project Graph pane

Select the SUPC peripheral library and configure it as shown below.

  • Enable the Increase low power mode efficiency bit to optimize and reduce power consumption in Standby mode.

Configuration Options pane

Information

This completes the configuration of the SUPC peripheral library. The SUPC manages the voltage reference and power supply of the device. It also controls the voltage regulators for the core domain. Voltage regulators need to be configured for low power applications, which helps in reducing power consumption.

Back to Top


Configure NVMCTRL Peripheral Library

The Non-volatile Memory Controller (NVMCTRL) is added by default to the project graph.

Select the NVMCTRL peripheral library and configure it as shown below.

  • Set Wait States to 1 to read the non-volatile memory. When the device is put in performance level 0, the device clock frequency can not exceed 12 MHz and one wait-state is required.
  • Set the Power Reduction Mode During Sleep to WAKEUP INSTANT. This bit configures the NVMCTRL to wake-up the Flash memory when the CPU wakes up from Standby mode, which allows it to reduce device wake-up time.
  • Disable the Instruction Cache to reduce the device's wake-up time. When the cache is enabled, the device will look for an instruction to fetch upon interrupt in the cache at first. If the instruction is found, the device wakes up quicker, but if not, a cache miss occurs and wake-up time is longer. This option is good to enable when the instruction to fetch upon an interrupt is always stored in the cache memory, which is not the case here as we have different interrupt sources.

Configuration Options pane

Information

This completes the configuration of the NVMCTRL peripheral library. The NVMCTRL is set to optimize the performances for waking the device up while keeping the power consumption as low as possible.

Back to Top


Configure LED and Wake-up Test Pins

Open the Pin Configuration tabs by clicking Tools > Pin Configuration.

Tools > Pin Configuration menu

Once the MPLAB® Harmony Configurator (MHC) Pin Settings window is opened, scroll-down to pin number 6 and 23, and then configure these pins as shown below:

  • Set the pin #6 as GPIO:

    • Pin ID = PB05
    • Custom Number = TEST_GPIO
    • Function = GPIO
    • Direction = Out
    • Latch = Low
  • Set the pin #23 as GPIO:
    • Pin ID = PB10
    • Custom Number = LED0
    • Function = GPIO
    • Direction = Out
    • Latch = High

Pin Settings window

Back to Top