1choice RTC_CLK_SRC
2    prompt "RTC clock source"
3    default RTC_CLK_SRC_INT_RC
4    help
5        Choose which clock is used as RTC clock source.
6
7        - "Internal 150kHz oscillator" option provides lowest deep sleep current
8            consumption, and does not require extra external components. However
9            frequency stability with respect to temperature is poor, so time may
10            drift in deep/light sleep modes.
11        - "External 32kHz crystal" provides better frequency stability, at the
12            expense of slightly higher (1uA) deep sleep current consumption.
13        - "External 32kHz oscillator" allows using 32kHz clock generated by an
14            external circuit. In this case, external clock signal must be connected
15            to 32K_XN pin. Amplitude should be <1.2V in case of sine wave signal,
16            and <1V in case of square wave signal. Common mode voltage should be
17            0.1 < Vcm < 0.5Vamp, where Vamp is the signal amplitude.
18            Additionally, 1nF capacitor must be connected between 32K_XP pin and
19            ground. 32K_XP pin can not be used as a GPIO in this case.
20        - "Internal 8.5MHz oscillator divided by 256" option results in higher
21            deep sleep current (by 5uA) but has better frequency stability than
22            the internal 150kHz oscillator. It does not require external components.
23
24    config RTC_CLK_SRC_INT_RC
25        bool "Internal 150kHz RC oscillator"
26    config RTC_CLK_SRC_EXT_CRYS
27        bool "External 32kHz crystal"
28        select ESP_SYSTEM_RTC_EXT_XTAL
29    config RTC_CLK_SRC_EXT_OSC
30        bool "External 32kHz oscillator at 32K_XN pin"
31        select ESP_SYSTEM_RTC_EXT_OSC
32    config RTC_CLK_SRC_INT_8MD256
33        bool "Internal 8.5MHz oscillator, divided by 256 (~33kHz)"
34endchoice
35
36choice RTC_EXT_CRYST_ADDIT_CURRENT_METHOD
37    prompt "Additional current for external 32kHz crystal"
38    depends on RTC_CLK_SRC_EXT_CRYS
39    depends on ESP32_REV_MIN_FULL < 200
40    default RTC_EXT_CRYST_ADDIT_CURRENT_NONE
41    help
42        With some 32kHz crystal configurations, the X32N and X32P pins may not have enough
43        drive strength to keep the crystal oscillating. Choose the method to provide
44        additional current from touchpad 9 to the external 32kHz crystal. Note that
45        the deep sleep current is slightly high (4-5uA) and the touchpad and the
46        wakeup sources of both touchpad and ULP are not available in method 1 and method 2.
47
48        This problem is fixed in ESP32 ECO 3, so this workaround is not needed. Setting the
49        project configuration to minimum revision ECO3 will disable this option, , allow
50        all wakeup sources, and save some code size.
51
52        - "None" option will not provide additional current to external crystal
53        - "Method 1" option can't ensure 100% to solve the external 32k crystal start failed
54            issue, but the touchpad can work in this method.
55        - "Method 2" option can solve the external 32k issue, but the touchpad can't work
56            in this method.
57
58    config RTC_EXT_CRYST_ADDIT_CURRENT_NONE
59        bool "None"
60    config RTC_EXT_CRYST_ADDIT_CURRENT
61        bool "Method 1"
62    config RTC_EXT_CRYST_ADDIT_CURRENT_V2
63        bool "Method 2"
64endchoice
65
66config RTC_CLK_CAL_CYCLES
67    int "Number of cycles for RTC_SLOW_CLK calibration"
68    default 3000 if RTC_CLK_SRC_EXT_CRYS || RTC_CLK_SRC_EXT_OSC || RTC_CLK_SRC_INT_8MD256
69    default 1024 if RTC_CLK_SRC_INT_RC
70    range 0 27000 if RTC_CLK_SRC_EXT_CRYS || RTC_CLK_SRC_EXT_OSC || RTC_CLK_SRC_INT_8MD256
71    range 0 32766 if RTC_CLK_SRC_INT_RC
72    help
73        When the startup code initializes RTC_SLOW_CLK, it can perform
74        calibration by comparing the RTC_SLOW_CLK frequency with main XTAL
75        frequency. This option sets the number of RTC_SLOW_CLK cycles measured
76        by the calibration routine. Higher numbers increase calibration
77        precision, which may be important for applications which spend a lot of
78        time in deep sleep. Lower numbers reduce startup time.
79
80        When this option is set to 0, clock calibration will not be performed at
81        startup, and approximate clock frequencies will be assumed:
82
83        - 150000 Hz if internal RC oscillator is used as clock source. For this use value 1024.
84        - 32768 Hz if the 32k crystal oscillator is used. For this use value 3000 or more.
85            In case more value will help improve the definition of the launch of the crystal.
86            If the crystal could not start, it will be switched to internal RC.
87
88config RTC_XTAL_CAL_RETRY
89    int "Number of attempts to repeat 32k XTAL calibration"
90    default 1
91    depends on RTC_CLK_SRC_EXT_CRYS
92    help
93        Number of attempts to repeat 32k XTAL calibration
94        before giving up and switching to the internal RC.
95        Increase this option if the 32k crystal oscillator
96        does not start and switches to internal RC.
97