diff --git a/components/esp32s2/clk.c b/components/esp32s2/clk.c
index 49b8ec135..4d2eb5c46 100644
--- a/components/esp32s2/clk.c
+++ b/components/esp32s2/clk.c
@@ -79,6 +79,11 @@ static const char *TAG = "clk";
 void esp_clk_init(void)
 {
     rtc_config_t cfg = RTC_CONFIG_DEFAULT();
+    RESET_REASON rst_reas;
+    rst_reas = rtc_get_reset_reason(0);
+    if (rst_reas == POWERON_RESET) {
+        cfg.cali_ocode = 1;
+    }
     rtc_init(cfg);
 
     assert(rtc_clk_xtal_freq_get() == RTC_XTAL_FREQ_40M);
diff --git a/components/soc/soc/esp32s2/i2c_ulp.h b/components/soc/soc/esp32s2/i2c_ulp.h
new file mode 100644
index 000000000..e7f4afa08
--- /dev/null
+++ b/components/soc/soc/esp32s2/i2c_ulp.h
@@ -0,0 +1,39 @@
+// Copyright 2015-2017 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+/**
+ * @file i2c_ulp.h
+ * @brief Register definitions for analog to calibrate o_code for getting a more precise voltage.
+ *
+ * This file lists register fields of ULP, located on an internal configuration
+ * bus. These definitions are used via macros defined in i2c_rtc_clk.h, by
+ * rtc_init function in rtc_init.c.
+ */
+
+#define I2C_ULP 0x61
+#define I2C_ULP_HOSTID 1
+
+#define I2C_ULP_IR_RESETB 0
+#define I2C_ULP_IR_RESETB_MSB 0
+#define I2C_ULP_IR_RESETB_LSB 0
+
+#define I2C_ULP_O_DONE_FLAG 3
+#define I2C_ULP_O_DONE_FLAG_MSB 0
+#define I2C_ULP_O_DONE_FLAG_LSB 0
+
+#define I2C_ULP_BG_O_DONE_FLAG 3
+#define I2C_ULP_BG_O_DONE_FLAG_MSB 3
+#define I2C_ULP_BG_O_DONE_FLAG_LSB 3
\ No newline at end of file
diff --git a/components/soc/soc/esp32s2/include/soc/rtc.h b/components/soc/soc/esp32s2/include/soc/rtc.h
index 2c27bd670..5f30be6d2 100644
--- a/components/soc/soc/esp32s2/include/soc/rtc.h
+++ b/components/soc/soc/esp32s2/include/soc/rtc.h
@@ -751,6 +751,7 @@ typedef struct {
     uint32_t xtal_fpu : 1;
     uint32_t bbpll_fpu : 1;
     uint32_t cpu_waiti_clk_gate : 1;
+    uint32_t cali_ocode : 1;        //!< Calibrate Ocode to make bangap voltage more precise.
 } rtc_config_t;
 
 /**
@@ -768,7 +769,8 @@ typedef struct {
     .rtc_dboost_fpd = 1, \
     .xtal_fpu = 0, \
     .bbpll_fpu = 0, \
-    .cpu_waiti_clk_gate = 1\
+    .cpu_waiti_clk_gate = 1, \
+    .cali_ocode = 0\
 }
 
 /**
diff --git a/components/soc/src/esp32s2/i2c_rtc_clk.h b/components/soc/src/esp32s2/i2c_rtc_clk.h
index 3bc445a31..0fff0eb07 100644
--- a/components/soc/src/esp32s2/i2c_rtc_clk.h
+++ b/components/soc/src/esp32s2/i2c_rtc_clk.h
@@ -16,6 +16,7 @@
 
 #include "i2c_apll.h"
 #include "i2c_bbpll.h"
+#include "i2c_ulp.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/components/soc/src/esp32s2/rtc_init.c b/components/soc/src/esp32s2/rtc_init.c
index 0aef6cc9a..fa7a7aa67 100644
--- a/components/soc/src/esp32s2/rtc_init.c
+++ b/components/soc/src/esp32s2/rtc_init.c
@@ -22,6 +22,9 @@
 #include "soc/spi_mem_reg.h"
 #include "soc/extmem_reg.h"
 #include "i2c_rtc_clk.h"
+#include "soc_log.h"
+
+static const char *TAG = "rtc_init";
 
 void rtc_init(rtc_config_t cfg)
 {
@@ -143,6 +146,56 @@ void rtc_init(rtc_config_t cfg)
         CLEAR_PERI_REG_MASK(RTC_CNTL_DIG_ISO_REG, RTC_CNTL_DG_PAD_FORCE_UNHOLD);
         CLEAR_PERI_REG_MASK(RTC_CNTL_DIG_ISO_REG, RTC_CNTL_DG_PAD_FORCE_NOISO);
     }
+    if (cfg.cali_ocode)
+    {
+        /*
+        Bangap output voltage is not precise when calibrate o-code by hardware sometimes, so need software o-code calibration(must close PLL).
+        Method:
+        1. read current cpu config, save in old_config;
+        2. switch cpu to xtal because PLL will be closed when o-code calibration;
+        3. begin o-code calibration;
+        4. wait o-code calibration done flag(odone_flag & bg_odone_flag) or timeout;
+        5. set cpu to old-config.
+        */
+        rtc_slow_freq_t slow_clk_freq = rtc_clk_slow_freq_get();
+        rtc_slow_freq_t rtc_slow_freq_x32k = RTC_SLOW_FREQ_32K_XTAL;
+        rtc_slow_freq_t rtc_slow_freq_8MD256 = RTC_SLOW_FREQ_8MD256;
+        rtc_cal_sel_t cal_clk = RTC_CAL_RTC_MUX;
+        if (slow_clk_freq == (rtc_slow_freq_x32k)) {
+            cal_clk = RTC_CAL_32K_XTAL;
+        } else if (slow_clk_freq == rtc_slow_freq_8MD256) {
+            cal_clk  = RTC_CAL_8MD256;
+        }
+
+        uint64_t max_delay_time_us = 10000;
+        uint32_t slow_clk_period = rtc_clk_cal(cal_clk, 100);
+        uint64_t max_delay_cycle = rtc_time_us_to_slowclk(max_delay_time_us, slow_clk_period);
+        uint64_t cycle0 = rtc_time_get();
+        uint64_t timeout_cycle = cycle0 + max_delay_cycle;
+        uint64_t cycle1 = 0;
+
+        rtc_cpu_freq_config_t old_config;
+        rtc_clk_cpu_freq_get_config(&old_config);
+        rtc_clk_cpu_freq_set_xtal();
+
+
+        I2C_WRITEREG_MASK_RTC(I2C_ULP, I2C_ULP_IR_RESETB, 0);
+        I2C_WRITEREG_MASK_RTC(I2C_ULP, I2C_ULP_IR_RESETB, 1);
+        bool odone_flag = 0;
+        bool bg_odone_flag = 0;
+        while(1) {
+            odone_flag = I2C_READREG_MASK_RTC(I2C_ULP, I2C_ULP_O_DONE_FLAG);
+            bg_odone_flag = I2C_READREG_MASK_RTC(I2C_ULP, I2C_ULP_BG_O_DONE_FLAG);
+            cycle1 = rtc_time_get();
+            if (odone_flag && bg_odone_flag)
+                break;
+            if (cycle1 >= timeout_cycle) {
+                SOC_LOGW(TAG, "o_code calibration fail");
+                break;
+            }
+        }
+        rtc_clk_cpu_freq_set_config(&old_config);
+    }
 }
 
 rtc_vddsdio_config_t rtc_vddsdio_get_config(void)
diff --git a/components/soc/src/esp32s2/rtc_sleep.c b/components/soc/src/esp32s2/rtc_sleep.c
index 8a037e36b..b0ceeb79c 100644
--- a/components/soc/src/esp32s2/rtc_sleep.c
+++ b/components/soc/src/esp32s2/rtc_sleep.c
@@ -107,6 +107,7 @@ void rtc_sleep_init(rtc_sleep_config_t cfg)
                             RTC_CNTL_CKGEN_I2C_PU | RTC_CNTL_PLL_I2C_PU |
                             RTC_CNTL_RFRX_PBUS_PU | RTC_CNTL_TXRF_I2C_PU);
     } else {
+	SET_PERI_REG_MASK(RTC_CNTL_REG, RTC_CNTL_REGULATOR_FORCE_PU);
         CLEAR_PERI_REG_MASK(RTC_CNTL_DIG_PWC_REG, RTC_CNTL_DG_WRAP_PD_EN);
         REG_SET_FIELD(RTC_CNTL_BIAS_CONF_REG, RTC_CNTL_DBG_ATTEN_DEEP_SLP, RTC_CNTL_DBG_ATTEN_LIGHTSLEEP_DEFAULT);
     }