kopia lustrzana https://github.com/espressif/esp-idf
66 wiersze
3.3 KiB
Plaintext
66 wiersze
3.3 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.
|
|
|
|
- "Internal 90kHz oscillator" option provides lowest deep sleep current
|
|
consumption, and does not require extra external components. However
|
|
frequency stability with respect to temperature is poor, so time may
|
|
drift in deep/light sleep modes.
|
|
- "External 32kHz crystal" provides better frequency stability, at the
|
|
expense of slightly higher (1uA) deep sleep current consumption.
|
|
- "External 32kHz oscillator" allows using 32kHz clock generated by an
|
|
external circuit. In this case, external clock signal must be connected
|
|
to 32K_XN pin. Amplitude should be <1.2V in case of sine wave signal,
|
|
and <1V in case of square wave signal. Common mode voltage should be
|
|
0.1 < Vcm < 0.5Vamp, where Vamp is the signal amplitude.
|
|
Additionally, 1nF capacitor must be connected between 32K_XP pin and
|
|
ground. 32K_XP pin can not be used as a GPIO in this case.
|
|
- "Internal 8MHz oscillator divided by 256" option results in higher
|
|
deep sleep current (by 5uA) but has better frequency stability than
|
|
the internal 90kHz oscillator. It does not require external components.
|
|
|
|
config RTC_CLK_SRC_INT_RC
|
|
bool "Internal 90kHz 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_XN pin"
|
|
select ESP_SYSTEM_RTC_EXT_OSC
|
|
config RTC_CLK_SRC_INT_8MD256
|
|
bool "Internal 8MHz oscillator, divided by 256 (~32kHz)"
|
|
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_8MD256
|
|
default 576 if RTC_CLK_SRC_INT_RC
|
|
range 0 125000
|
|
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:
|
|
|
|
- 90000 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.
|
|
|
|
config RTC_XTAL_CAL_RETRY
|
|
int "Number of attempts to repeat 32k XTAL calibration"
|
|
default 3
|
|
depends on RTC_CLK_SRC_EXT_CRYS
|
|
help
|
|
Number of attempts to repeat 32k XTAL calibration
|
|
before giving up and switching to the internal RC.
|
|
Increase this option if the 32k crystal oscillator
|
|
does not start and switches to internal RC.
|