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docs: update the description for RTC Clock Sources for esp32 and esp32s2

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This commit is contained in:
Wang Fang
2020-09-23 17:13:19 +08:00
parent 3c2f2aaffe
commit a50966cf7a
3 changed files with 17 additions and 14 deletions
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components/esp32/Kconfig
+4 -4
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@@ -545,11 +545,11 @@ menu "ESP32-specific"
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_XP pin. Amplitude should be <1.2V in case of sine wave signal,
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_XN pin and
ground. 32K_XN pin can not be used as a GPIO in this case.
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 8.5MHz oscillator divided by 256" option results in higher
deep sleep current (by 5uA) but has better frequency stability than
the internal 150kHz oscillator. It does not require external components.
@@ -560,7 +560,7 @@ menu "ESP32-specific"
bool "External 32kHz crystal"
select ESP_SYSTEM_RTC_EXT_XTAL
config ESP32_RTC_CLK_SRC_EXT_OSC
bool "External 32kHz oscillator at 32K_XP pin"
bool "External 32kHz oscillator at 32K_XN pin"
config ESP32_RTC_CLK_SRC_INT_8MD256
bool "Internal 8.5MHz oscillator, divided by 256 (~33kHz)"
endchoice