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soc/rtc: Bypass touchpad current to external 32k crystal oscillator

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This commit is contained in:
Zhang Jun Yi 2018-05-23 15:24:09 +08:00 committed by Angus Gratton
parent f608afbe6b
commit 413b6487fb
1 changed files with 28 additions and 5 deletions
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29
components/soc/esp32/rtc_clk.c
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@ -58,7 +58,7 @@
#define APLL_CAL_DELAY_2 0x3f
#define APLL_CAL_DELAY_3 0x1f
#define XTAL_32K_DAC_VAL 1
#define XTAL_32K_DAC_VAL 3
#define XTAL_32K_DRES_VAL 3
#define XTAL_32K_DBIAS_VAL 0
@ -111,14 +111,34 @@ static const char* TAG = "rtc_clk";
static void rtc_clk_32k_enable_common(int dac, int dres, int dbias)
{
SET_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_X32N_MUX_SEL | RTC_IO_X32P_MUX_SEL);
CLEAR_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG,
RTC_IO_X32P_RDE | RTC_IO_X32P_RUE | RTC_IO_X32N_RUE |
RTC_IO_X32N_RDE | RTC_IO_X32N_MUX_SEL | RTC_IO_X32P_MUX_SEL);
SET_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_X32N_MUX_SEL | RTC_IO_X32P_MUX_SEL);
/* Set the parameters of xtal
dac --> current
dres --> resistance
dbias --> bais voltage
*/
REG_SET_FIELD(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_DAC_XTAL_32K, dac);
REG_SET_FIELD(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_DRES_XTAL_32K, dres);
REG_SET_FIELD(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_DBIAS_XTAL_32K, dbias);
SET_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_XPD_XTAL_32K);
/* TOUCH sensor can provide additional current to external XTAL.
In some case, X32N and X32P PAD don't have enough drive capability to start XTAL */
SET_PERI_REG_MASK(RTC_IO_TOUCH_CFG_REG, RTC_IO_TOUCH_XPD_BIAS_M);
/* Tie PAD Touch8 to VDD
NOTE: TOUCH8 and TOUCH9 register settings are reversed except for DAC, so we set RTC_IO_TOUCH_PAD9_REG here instead
*/
SET_PERI_REG_MASK(RTC_IO_TOUCH_PAD9_REG, RTC_IO_TOUCH_PAD9_TIE_OPT_M);
/* Set the current used to compensate TOUCH PAD8 */
SET_PERI_REG_BITS(RTC_IO_TOUCH_PAD8_REG, RTC_IO_TOUCH_PAD8_DAC, 4, RTC_IO_TOUCH_PAD8_DAC_S);
/* Power up TOUCH8
So the Touch DAC start to drive some current from VDD to TOUCH8(which is also XTAL-N)
*/
SET_PERI_REG_MASK(RTC_IO_TOUCH_PAD9_REG, RTC_IO_TOUCH_PAD9_XPD_M);
/* Power up external xtal */
SET_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_XPD_XTAL_32K_M);
}
void rtc_clk_32k_enable(bool enable)
@ -126,7 +146,10 @@ void rtc_clk_32k_enable(bool enable)
if (enable) {
rtc_clk_32k_enable_common(XTAL_32K_DAC_VAL, XTAL_32K_DRES_VAL, XTAL_32K_DBIAS_VAL);
} else {
/* Disable X32N and X32P pad drive external xtal */
CLEAR_PERI_REG_MASK(RTC_IO_XTAL_32K_PAD_REG, RTC_IO_XPD_XTAL_32K);
/* Power down TOUCH */
CLEAR_PERI_REG_MASK(RTC_IO_TOUCH_PAD9_REG, RTC_IO_TOUCH_PAD9_XPD_M);
}
}