Espressif ESP32-S2 Programming Manual page 1042

Chapter 2. API Reference
enabled). Maximum extra latency is 40 us (when frequency scaling is enabled, and a switch from 40 MHz to 80 MHz
is performed on interrupt entry).
Dynamic frequency scaling (DFS) and automatic light sleep can be enabled in an application by calling
the function esp_pm_configure().
esp_pm_config_esp32s2_t. In this structure, three fields need to be initialized:
• max_freq_mhz:
ESP_PM_CPU_FREQ_MAX lock is acquired. This field will usually be set to the default CPU frequency.
• min_freq_mhz:
ESP_PM_APB_FREQ_MAX lock is acquired. This field can be set to the XTAL frequency value, or the XTAL
frequency divided by an integer. Note that 10 MHz is the lowest frequency at which the default REF_TICK
clock of 1 MHz can be generated.
• light_sleep_enable: Whether the system should automatically enter light sleep when no locks are
acquired (true/false).
Alternatively, if you enable the option
quency will be determined by the
CPU frequency will be locked to the XTAL frequency.
Note: Automatic light sleep is based on FreeRTOS Tickless Idle functionality.
sleep is requested while the option
esp_pm_configure()
Note: In light sleep, peripherals are clock gated, and interrupts (from GPIOs and internal peripherals) will not be
generated. A wakeup source described in the
light sleep state.
For example, the EXT0 and EXT1 wakeup sources can be used to wake up the chip via a GPIO.
Power Management Locks
Applications have the ability to acquire/release locks in order to control the power management algorithm. When an
application acquires a lock, the power management algorithm operation is restricted in a way described below. When
the lock is released, such restrictions are removed.
Power management locks have acquire/release counters. If the lock has been acquired a number of times, it needs to
be released the same number of times to remove associated restrictions.
ESP32-S2 supports three types of locks described in the table below.
Lock
ESP_PM_CPU_FREQ_MAX
ESP_PM_APB_FREQ_MAX
ESP_PM_NO_LIGHT_SLEEP Disables automatic switching to light sleep.
ESP32-S2 Power Management Algorithm
The table below shows how CPU and APB frequencies will be switched if dynamic frequency scaling is
enabled. You can specify the maximum CPU frequency with either
FIG_ESP32S2_DEFAULT_CPU_FREQ_MHZ.
Espressif Systems
Its argument is a structure defining the frequency scaling settings,
Maximum CPU frequency in MHz, i.e., the frequency used when the
Minimum CPU frequency in MHz, i.e., the frequency used when only the
CONFIG_PM_DFS_INIT_AUTO
CONFIG_ESP32S2_DEFAULT_CPU_FREQ_MHZ
CONFIG_FREERTOS_USE_TICKLESS_IDLE
will return the error ESP_ERR_NOT_SUPPORTED.
Sleep Modes
Description
Requests CPU
with esp_pm_configure(). For ESP32-S2, this value can be set to
80 MHz, 160 MHz, or 240 MHz.
Requests the APB frequency to be at the maximum supported value. For
ESP32-S2, this is 80 MHz.
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in menuconfig, the maximum CPU fre-
documentation can be used to trigger wakeup from the
frequency to be at
esp_pm_configure()
1031
setting, and the minimum
If automatic light
is not enabled in menuconfig,
the maximum value
or CON-
Release v4.4
set