mirror of
https://github.com/espressif/esp-idf.git
synced 2024-10-05 20:47:46 -04:00
40 lines
1.8 KiB
Plaintext
40 lines
1.8 KiB
Plaintext
choice RTC_CLK_SRC
|
|
prompt "RTC clock source"
|
|
default RTC_CLK_SRC_INT_RC
|
|
help
|
|
Choose which clock is used as RTC clock source.
|
|
|
|
config RTC_CLK_SRC_INT_RC
|
|
bool "Internal 150 kHz RC oscillator"
|
|
config RTC_CLK_SRC_EXT_CRYS
|
|
bool "External 32kHz crystal"
|
|
select ESP_SYSTEM_RTC_EXT_XTAL
|
|
config RTC_CLK_SRC_EXT_OSC
|
|
bool "External 32kHz oscillator at 32K_XP pin"
|
|
select ESP_SYSTEM_RTC_EXT_OSC
|
|
config RTC_CLK_SRC_INT_RC32K
|
|
bool "Internal 32kHz RC oscillator"
|
|
endchoice
|
|
|
|
config RTC_CLK_CAL_CYCLES
|
|
int "Number of cycles for RTC_SLOW_CLK calibration"
|
|
default 3000 if RTC_CLK_SRC_EXT_CRYS || RTC_CLK_SRC_EXT_OSC || RTC_CLK_SRC_INT_RC32K
|
|
default 1024 if RTC_CLK_SRC_INT_RC
|
|
range 0 27000 if RTC_CLK_SRC_EXT_CRYS || RTC_CLK_SRC_EXT_OSC || RTC_CLK_SRC_INT_RC32K
|
|
range 0 32766 if 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:
|
|
|
|
- 136000 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.
|