esp-idf/components/esp32c3/Kconfig

menu "ESP32C3-Specific"
    visible if IDF_TARGET_ESP32C3

    choice ESP32C3_DEFAULT_CPU_FREQ_MHZ
        prompt "CPU frequency"
        default ESP32C3_DEFAULT_CPU_FREQ_40 if IDF_ENV_FPGA
        default ESP32C3_DEFAULT_CPU_FREQ_160 if !IDF_ENV_FPGA
        help
            CPU frequency to be set on application startup.

        config ESP32C3_DEFAULT_CPU_FREQ_40
            bool "40 MHz"
            depends on IDF_ENV_FPGA
        config ESP32C3_DEFAULT_CPU_FREQ_80
            bool "80 MHz"
        config ESP32C3_DEFAULT_CPU_FREQ_160
            bool "160 MHz"
    endchoice

    config ESP32C3_DEFAULT_CPU_FREQ_MHZ
        int
        default 40 if ESP32C3_DEFAULT_CPU_FREQ_40
        default 80 if ESP32C3_DEFAULT_CPU_FREQ_80
        default 160 if ESP32C3_DEFAULT_CPU_FREQ_160

    choice ESP32C3_REV_MIN
        prompt "Minimum Supported ESP32-C3 Revision"
        default ESP32C3_REV_MIN_3
        help
            Minimum revision that ESP-IDF would support.

            Only supporting higher chip revisions can reduce binary size.

        config ESP32C3_REV_MIN_0
            bool "Rev 0"
        config ESP32C3_REV_MIN_1
            bool "Rev 1"
        config ESP32C3_REV_MIN_2
            bool "Rev 2"
        config ESP32C3_REV_MIN_3
            bool "Rev 3"
    endchoice

    config ESP32C3_REV_MIN
        int
        default 0 if ESP32C3_REV_MIN_0
        default 1 if ESP32C3_REV_MIN_1
        default 2 if ESP32C3_REV_MIN_2
        default 3 if ESP32C3_REV_MIN_3

    choice ESP32C3_TIME_SYSCALL
        prompt "Timers used for gettimeofday function"
        default ESP32C3_TIME_SYSCALL_USE_RTC_SYSTIMER
        help
            This setting defines which hardware timers are used to
            implement 'gettimeofday' and 'time' functions in C library.

            - If both high-resolution (systimer) and RTC timers are used, timekeeping will
              continue in deep sleep. Time will be reported at 1 microsecond
              resolution. This is the default, and the recommended option.
            - If only high-resolution timer (systimer) is used, gettimeofday will
              provide time at microsecond resolution.
              Time will not be preserved when going into deep sleep mode.
            - If only RTC timer is used, timekeeping will continue in
              deep sleep, but time will be measured at 6.(6) microsecond
              resolution. Also the gettimeofday function itself may take
              longer to run.
            - If no timers are used, gettimeofday and time functions
              return -1 and set errno to ENOSYS.
            - When RTC is used for timekeeping, two RTC_STORE registers are
              used to keep time in deep sleep mode.

        config ESP32C3_TIME_SYSCALL_USE_RTC_SYSTIMER
            bool "RTC and high-resolution timer"
            select ESP_TIME_FUNCS_USE_RTC_TIMER
            select ESP_TIME_FUNCS_USE_ESP_TIMER
        config ESP32C3_TIME_SYSCALL_USE_RTC
            bool "RTC"
            select ESP_TIME_FUNCS_USE_RTC_TIMER
        config ESP32C3_TIME_SYSCALL_USE_SYSTIMER
            bool "High-resolution timer"
            select ESP_TIME_FUNCS_USE_ESP_TIMER
        config ESP32C3_TIME_SYSCALL_USE_NONE
            bool "None"
            select ESP_TIME_FUNCS_USE_NONE
    endchoice

    choice ESP32C3_RTC_CLK_SRC
        prompt "RTC clock source"
        default ESP32C3_RTC_CLK_SRC_INT_RC
        help
            Choose which clock is used as RTC clock source.

        config ESP32C3_RTC_CLK_SRC_INT_RC
            bool "Internal 150kHz RC oscillator"
        config ESP32C3_RTC_CLK_SRC_EXT_CRYS
            bool "External 32kHz crystal"
            select ESP_SYSTEM_RTC_EXT_XTAL
        config ESP32C3_RTC_CLK_SRC_EXT_OSC
            bool "External 32kHz oscillator at 32K_XP pin"
            select ESP_SYSTEM_RTC_EXT_OSC
        config ESP32C3_RTC_CLK_SRC_INT_8MD256
            bool "Internal 8MHz oscillator, divided by 256 (~32kHz)"
    endchoice

    config ESP32C3_RTC_CLK_CAL_CYCLES
        int "Number of cycles for RTC_SLOW_CLK calibration"
        default 3000 if ESP32C3_RTC_CLK_SRC_EXT_CRYS || ESP32C3_RTC_CLK_SRC_EXT_OSC || ESP32C3_RTC_CLK_SRC_INT_8MD256
        default 1024 if ESP32C3_RTC_CLK_SRC_INT_RC
        range 0 27000 if ESP32C3_RTC_CLK_SRC_EXT_CRYS || ESP32C3_RTC_CLK_SRC_EXT_OSC || ESP32C3_RTC_CLK_SRC_INT_8MD256
        range 0 32766 if ESP32C3_RTC_CLK_SRC_INT_RC
        help
            When the startup code initializes RTC_SLOW_CLK, it can perform
            calibration by comparing the RTC_SLOW_CLK frequency with main XTAL
            frequency. This option sets the number of RTC_SLOW_CLK cycles measured
            by the calibration routine. Higher numbers increase calibration
            precision, which may be important for applications which spend a lot of
            time in deep sleep. Lower numbers reduce startup time.

            When this option is set to 0, clock calibration will not be performed at
            startup, and approximate clock frequencies will be assumed:

            - 150000 Hz if internal RC oscillator is used as clock source. For this use value 1024.
            - 32768 Hz if the 32k crystal oscillator is used. For this use value 3000 or more.
              In case more value will help improve the definition of the launch of the crystal.
              If the crystal could not start, it will be switched to internal RC.

endmenu  # ESP32C3-Specific